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elektroda.net NewsGroups Forum Index - Electronics Design - **Small and large signal S parameters**

Guest

Sat Feb 09, 2019 12:45 pm

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

Guest

Sat Feb 09, 2019 1:45 pm

Am 09.02.19 um 12:36 schrieb dakupoto_at_gmail.com:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

Yes. It's currently Gospel that large signal s-parameters are

required for oscillator design. Oscillators are inherently

nonlinear since there must be some limiting / gain control

or the amplitude would collapse or explode otherwise.

I don't see that so extreme. I got the the point where the

crystal phase noise is all that matters without HB.

In the Agilent world, look for x-parameters.

Here are some papers from Rohde; he is a mass publisher

so it will be redundant.

There is more interesting material on the synergy microwave web site.

Older s-parameters should be small signal, esp. when there is

only bias given and no levels.

I'm just trying to determine myself if I could use harmonic

balance to simulate the noise behavior of a chopper amplifier

or if that is too non-linear. I'm still struggling with

importing spice models.

cheers,

Gerhard

<

https://depositonce.tu-berlin.de/bitstream/11303/1306/1/Dokument_16.pdf >

<

https://www.unibw.de/technische-informatik/mitarbeiter/professoren/large-signal-oszillator-noise-analysis-then-and-today-2.pdf

>

< https://synergymwave.com/articles/2013/04/full_article.pdf >

<

https://www.mes.tu-darmstadt.de/media/mikroelektronische_systeme/pdf_3/ewme2010/proceedings/sessionvii/hartnagel_slides.pdf

>

Guest

Sat Feb 09, 2019 2:45 pm

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's initially

in the small signal condition, so the resonator + small signal S params

have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

Cheers

Phil Hobbs

--

Dr Philip C D Hobbs

Principal Consultant

ElectroOptical Innovations LLC / Hobbs ElectroOptics

Optics, Electro-optics, Photonics, Analog Electronics

Briarcliff Manor NY 10510

http://electrooptical.net

http://hobbs-eo.com

Guest

Sat Feb 09, 2019 3:45 pm

Phil Hobbs wrote...

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Small signal S parameter analysis is based on small

signal levels and a linearized circuit, with a DC

operating point(bias) condition. ...

The first thing an oscillator has to do is to start up.

It's initially in the small signal condition ...

I'd just like to add that small-signal analysis can be

very useful in large-signal situations. For example,

I'm working on designing high-voltage amplifiers with

power MOSFETs. These are capable of fast slewing and

high power levels, with excursions of hundreds of volts,

and high currents into capacitive loads. At first it

appeared that small-signal measurements and analysis

would not be so useful. But then I realized that when

the circuit was non-linear, slewing, delivering current,

I'd use the appropriate analysis, i = C dV/dt, etc.,

but after it was done slewing, it'd be the steady-state

condition that was most important, and most of my effort

went into solving the equations for that, and using them

to make the design rock solid. I made sure the amplifier

would then be operating class-A. This scheme worked well,

and I created a simple inexpensive design for a 1200-volt

DC power amplifier that has a -3dB bandwidth of 1 MHz.

It's gratifying to see the amplifier perform well, fast,

powerful, yet stable, with low measured phase shifts at

1MHz and beyond, so that with a transducer, it can work

well in a wideband servo. Small-signal analysis rocks!

BTW, at these frequencies, I wasn't using s-parameters.

--

Thanks,

- Win

Guest

Sat Feb 09, 2019 4:45 pm

Phil Hobbs <pcdhSpamMeSenseless_at_electrooptical.net> wrote in

news:JcqdnTH2ovEHUcPBnZ2dnUU7-eednZ2d_at_supernews.com:

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias)

condition. Large signal S parameter extends this scheme to high

power operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's

initially in the small signal condition, so the resonator + small

signal S params have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

Cheers

Phil Hobbs

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias)

condition. Large signal S parameter extends this scheme to high

power operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's

initially in the small signal condition, so the resonator + small

signal S params have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

Cheers

Phil Hobbs

In switch mode power supply design and use, this is known as "slow

start" of "hard start". If one punches the start of some

oscillators too hard the initial swing does not start and the

oscillator 'latches up' and the circuit start fails. In many cases

that input needs to be dampened or led or lagged to achieve a "soft

start" condition that ensures that the oscillator always starts.

Guest

Sat Feb 09, 2019 5:45 pm

On Sat, 9 Feb 2019 03:36:06 -0800 (PST), dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ?

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ?

Think about the Barkhausen criterion, the total loop gain must be

larger than 1 and the total phase around the loop must be correct.

At oscillator startup, there is always some amplifier input related

white thermal noise. The amplifier amplifies the noise G times. This

noise is them coupled back to the input via the frequency selective

network with quality Q with correct phase, thus a narrow band noise

with bandwidth f/Q is connected back to amplifier input. The noise is

amplified nearly to G² times and then running again through the filter

and having f/Q² bandwidth at amplifier input. During next iteration

the signal is amplified up to G³ and filtered again to f/Q³ and so on.

This continues, until the signal amplitude is limited by the available

voltage swing.

The small signal s-parameters are initially critical, since the

Barkhausen criterions must be satisfied from thermal noise levels up

to limiting.

Guest

Sat Feb 09, 2019 6:45 pm

On Sat, 09 Feb 2019 17:52:12 +0200, upsidedown_at_downunder.com wrote:

On Sat, 9 Feb 2019 03:36:06 -0800 (PST), dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ?

Think about the Barkhausen criterion, the total loop gain must be

larger than 1 and the total phase around the loop must be correct.

At oscillator startup, there is always some amplifier input related

white thermal noise. The amplifier amplifies the noise G times. This

noise is them coupled back to the input via the frequency selective

network with quality Q with correct phase, thus a narrow band noise

with bandwidth f/Q is connected back to amplifier input. The noise is

amplified nearly to G² times and then running again through the filter

and having f/Q² bandwidth at amplifier input. During next iteration

the signal is amplified up to G³ and filtered again to f/Q³ and so on.

This continues, until the signal amplitude is limited by the available

voltage swing.

The small signal s-parameters are initially critical, since the

Barkhausen criterions must be satisfied from thermal noise levels up

to limiting.

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ?

Think about the Barkhausen criterion, the total loop gain must be

larger than 1 and the total phase around the loop must be correct.

At oscillator startup, there is always some amplifier input related

white thermal noise. The amplifier amplifies the noise G times. This

noise is them coupled back to the input via the frequency selective

network with quality Q with correct phase, thus a narrow band noise

with bandwidth f/Q is connected back to amplifier input. The noise is

amplified nearly to G² times and then running again through the filter

and having f/Q² bandwidth at amplifier input. During next iteration

the signal is amplified up to G³ and filtered again to f/Q³ and so on.

This continues, until the signal amplitude is limited by the available

voltage swing.

The small signal s-parameters are initially critical, since the

Barkhausen criterions must be satisfied from thermal noise levels up

to limiting.

If the amp's transfer function has the right (ie, wrong) shape you can

make an oscillator that will run but not start.

--

John Larkin Highland Technology, Inc

lunatic fringe electronics

Guest

Sat Feb 09, 2019 7:45 pm

On 2/9/19 9:29 AM, Winfield Hill wrote:

Phil Hobbs wrote...

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Small signal S parameter analysis is based on small

signal levels and a linearized circuit, with a DC

operating point(bias) condition. ...

The first thing an oscillator has to do is to start up.

It's initially in the small signal condition ...

I'd just like to add that small-signal analysis can be

very useful in large-signal situations. For example,

I'm working on designing high-voltage amplifiers with

power MOSFETs. These are capable of fast slewing and

high power levels, with excursions of hundreds of volts,

and high currents into capacitive loads. At first it

appeared that small-signal measurements and analysis

would not be so useful. But then I realized that when

the circuit was non-linear, slewing, delivering current,

I'd use the appropriate analysis, i = C dV/dt, etc.,

but after it was done slewing, it'd be the steady-state

condition that was most important, and most of my effort

went into solving the equations for that, and using them

to make the design rock solid. I made sure the amplifier

would then be operating class-A. This scheme worked well,

and I created a simple inexpensive design for a 1200-volt

DC power amplifier that has a -3dB bandwidth of 1 MHz.

It's gratifying to see the amplifier perform well, fast,

powerful, yet stable, with low measured phase shifts at

1MHz and beyond, so that with a transducer, it can work

well in a wideband servo. Small-signal analysis rocks!

BTW, at these frequencies, I wasn't using s-parameters.

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Small signal S parameter analysis is based on small

signal levels and a linearized circuit, with a DC

operating point(bias) condition. ...

The first thing an oscillator has to do is to start up.

It's initially in the small signal condition ...

I'd just like to add that small-signal analysis can be

very useful in large-signal situations. For example,

I'm working on designing high-voltage amplifiers with

power MOSFETs. These are capable of fast slewing and

high power levels, with excursions of hundreds of volts,

and high currents into capacitive loads. At first it

appeared that small-signal measurements and analysis

would not be so useful. But then I realized that when

the circuit was non-linear, slewing, delivering current,

I'd use the appropriate analysis, i = C dV/dt, etc.,

but after it was done slewing, it'd be the steady-state

condition that was most important, and most of my effort

went into solving the equations for that, and using them

to make the design rock solid. I made sure the amplifier

would then be operating class-A. This scheme worked well,

and I created a simple inexpensive design for a 1200-volt

DC power amplifier that has a -3dB bandwidth of 1 MHz.

It's gratifying to see the amplifier perform well, fast,

powerful, yet stable, with low measured phase shifts at

1MHz and beyond, so that with a transducer, it can work

well in a wideband servo. Small-signal analysis rocks!

BTW, at these frequencies, I wasn't using s-parameters.

Yup. The math isn't hard, and (when both approaches apply) one formula

has more information than a week's worth of simulations.

Cheers

Phil Hobbs

--

Dr Philip C D Hobbs

Principal Consultant

ElectroOptical Innovations LLC / Hobbs ElectroOptics

Optics, Electro-optics, Photonics, Analog Electronics

Briarcliff Manor NY 10510

http://electrooptical.net

http://hobbs-eo.com

Guest

Sat Feb 09, 2019 7:45 pm

On Sat, 09 Feb 2019 09:22:56 -0800, John Larkin

<jjlarkin_at_highlandtechnology.com> wrote:

On Sat, 09 Feb 2019 17:52:12 +0200, upsidedown_at_downunder.com wrote:

On Sat, 9 Feb 2019 03:36:06 -0800 (PST), dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ?

Think about the Barkhausen criterion, the total loop gain must be

larger than 1 and the total phase around the loop must be correct.

At oscillator startup, there is always some amplifier input related

white thermal noise. The amplifier amplifies the noise G times. This

noise is them coupled back to the input via the frequency selective

network with quality Q with correct phase, thus a narrow band noise

with bandwidth f/Q is connected back to amplifier input. The noise is

amplified nearly to G² times and then running again through the filter

and having f/Q² bandwidth at amplifier input. During next iteration

the signal is amplified up to G³ and filtered again to f/Q³ and so on.

This continues, until the signal amplitude is limited by the available

voltage swing.

The small signal s-parameters are initially critical, since the

Barkhausen criterions must be satisfied from thermal noise levels up

to limiting.

If the amp's transfer function has the right (ie, wrong) shape you can

make an oscillator that will run but not start.

On Sat, 9 Feb 2019 03:36:06 -0800 (PST), dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ?

Think about the Barkhausen criterion, the total loop gain must be

larger than 1 and the total phase around the loop must be correct.

At oscillator startup, there is always some amplifier input related

white thermal noise. The amplifier amplifies the noise G times. This

noise is them coupled back to the input via the frequency selective

network with quality Q with correct phase, thus a narrow band noise

with bandwidth f/Q is connected back to amplifier input. The noise is

amplified nearly to G² times and then running again through the filter

and having f/Q² bandwidth at amplifier input. During next iteration

the signal is amplified up to G³ and filtered again to f/Q³ and so on.

This continues, until the signal amplitude is limited by the available

voltage swing.

The small signal s-parameters are initially critical, since the

Barkhausen criterions must be satisfied from thermal noise levels up

to limiting.

If the amp's transfer function has the right (ie, wrong) shape you can

make an oscillator that will run but not start.

Biasing the amplifier into class-C and the oscillator will not

automatically start. Once started the amplification in class C will

kick the resonator once each cycle.

In practice, such oscillators may start by quickly applying the

operating voltage, which allows some collector current to flow

momentarily. You may end up with an oscillator, which starts nicely

when battery powered but not when mains powered through linear power

supply with big electrolytes . With such power supply, the voltage

may start too slowly to initiate the initial cycle.

Guest

Mon Feb 11, 2019 12:45 pm

On Saturday, February 9, 2019 at 7:50:43 AM UTC-5, Phil Hobbs wrote:

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's initially

in the small signal condition, so the resonator + small signal S params

have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

Cheers

Phil Hobbs

--

Dr Philip C D Hobbs

Principal Consultant

ElectroOptical Innovations LLC / Hobbs ElectroOptics

Optics, Electro-optics, Photonics, Analog Electronics

Briarcliff Manor NY 10510

http://electrooptical.net

http://hobbs-eo.com

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's initially

in the small signal condition, so the resonator + small signal S params

have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

Cheers

Phil Hobbs

--

Dr Philip C D Hobbs

Principal Consultant

ElectroOptical Innovations LLC / Hobbs ElectroOptics

Optics, Electro-optics, Photonics, Analog Electronics

Briarcliff Manor NY 10510

http://electrooptical.net

http://hobbs-eo.com

It depends on the type of oscillator one is looking at.

A differential oscillator, by its very nature, does not need any transistor biasing, and so it does not matter

if the S parameters are used or not.

In addition, for the new breed of transistors(e/g/.

HFA3134 from Renessas Semiconductor) the datasheet DOES NOT list ANY S parameters. With a fT of 8 GHz, it

would work very well in the RF - microwave frequency range.

Guest

Mon Feb 11, 2019 12:45 pm

On Saturday, February 9, 2019 at 7:31:54 AM UTC-5, Gerhard Hoffmann wrote:

Am 09.02.19 um 12:36 schrieb dakupoto_at_gmail.com:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

Yes. It's currently Gospel that large signal s-parameters are

required for oscillator design. Oscillators are inherently

nonlinear since there must be some limiting / gain control

or the amplitude would collapse or explode otherwise.

I don't see that so extreme. I got the the point where the

crystal phase noise is all that matters without HB.

In the Agilent world, look for x-parameters.

Here are some papers from Rohde; he is a mass publisher

so it will be redundant.

There is more interesting material on the synergy microwave web site.

Older s-parameters should be small signal, esp. when there is

only bias given and no levels.

I'm just trying to determine myself if I could use harmonic

balance to simulate the noise behavior of a chopper amplifier

or if that is too non-linear. I'm still struggling with

importing spice models.

cheers,

Gerhard

https://depositonce.tu-berlin.de/bitstream/11303/1306/1/Dokument_16.pdf

https://www.unibw.de/technische-informatik/mitarbeiter/professoren/large-signal-oszillator-noise-analysis-then-and-today-2.pdf

https://synergymwave.com/articles/2013/04/full_article.pdf

https://www.mes.tu-darmstadt.de/media/mikroelektronische_systeme/pdf_3/ewme2010/proceedings/sessionvii/hartnagel_slides.pdf

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

Yes. It's currently Gospel that large signal s-parameters are

required for oscillator design. Oscillators are inherently

nonlinear since there must be some limiting / gain control

or the amplitude would collapse or explode otherwise.

I don't see that so extreme. I got the the point where the

crystal phase noise is all that matters without HB.

In the Agilent world, look for x-parameters.

Here are some papers from Rohde; he is a mass publisher

so it will be redundant.

There is more interesting material on the synergy microwave web site.

Older s-parameters should be small signal, esp. when there is

only bias given and no levels.

I'm just trying to determine myself if I could use harmonic

balance to simulate the noise behavior of a chopper amplifier

or if that is too non-linear. I'm still struggling with

importing spice models.

cheers,

Gerhard

https://depositonce.tu-berlin.de/bitstream/11303/1306/1/Dokument_16.pdf

https://www.unibw.de/technische-informatik/mitarbeiter/professoren/large-signal-oszillator-noise-analysis-then-and-today-2.pdf

https://synergymwave.com/articles/2013/04/full_article.pdf

https://www.mes.tu-darmstadt.de/media/mikroelektronische_systeme/pdf_3/ewme2010/proceedings/sessionvii/hartnagel_slides.pdf

It certainly is the Gospel to use large signal S

parameters, but things are changing rapidly. A new

breed of bi-junction transistors(e.g., HFA3134 -

Renesas Semiconductor) with a transition frequency

of 8 GHz(well in the RF/microwave range) DOES NOY

require the use of S parameters at all. The easily

downloadable data sheet does not contain any S parameters. I have used it to SPICE simulate common emitter/base feedback/negative resistance oscillators

upto 2 GHz. No issues at all.

My design scheme is simple.

1. AS a real-world oscillator cannot be expedted to

dump all the signal energy at the design frequency, define a set of tolerances (e.g., 5%) on the first

n (3 - 4) harmonics.

2. Compute passive component values e.g., for a common

emiiter feedback oscillator, with a simple C program

(to remove silly calculation errors) and then SPICE

simulate it with transientr analysis.

3. Fourier transform transient analysis output, and

compute power spectrun and check if the frequencies

corresponding to the first n(3 - 4) highest peaks fall

within the predefined tolerances. If not, adjust

resonator component values and iterate through the

above steps till tolerances ae satisfied - convergence.

If yes, task is complete.

I do have a copy of Rohde's 2005 book on microwave

oscillator design, but suffers from the same

problem as books on this topic by others(Grebennikov,

Ludwig Bretchko, Pozar etc.,) hundreds of pages of

theory.

We do have ADS at work, but most of us think that

the learning curve is very steep, and the results are

very non-intuitive.

Thank you very much for the URLs _ I will definitely

look through them.

Guest

Mon Feb 11, 2019 4:45 pm

On 2/11/19 6:44 AM, dakupoto_at_gmail.com wrote:

On Saturday, February 9, 2019 at 7:50:43 AM UTC-5, Phil Hobbs wrote:

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's initially

in the small signal condition, so the resonator + small signal S params

have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

It depends on the type of oscillator one is looking at.

A differential oscillator, by its very nature, does not need any transistor biasing, and so it does not matter

if the S parameters are used or not.

In addition, for the new breed of transistors(e/g/.

HFA3134 from Renessas Semiconductor) the datasheet DOES NOT list ANY S parameters. With a fT of 8 GHz, it

would work very well in the RF - microwave frequency range.

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's initially

in the small signal condition, so the resonator + small signal S params

have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

It depends on the type of oscillator one is looking at.

A differential oscillator, by its very nature, does not need any transistor biasing, and so it does not matter

if the S parameters are used or not.

In addition, for the new breed of transistors(e/g/.

HFA3134 from Renessas Semiconductor) the datasheet DOES NOT list ANY S parameters. With a fT of 8 GHz, it

would work very well in the RF - microwave frequency range.

Sure. It has a super-detailed SPICE model for both the device and the

package parasitics, which is going to be more useful than S parameters.

You can generate S parameters from the model, but going the other way is

a lot more complicated.

Cheers

Phil Hobbs

--

Dr Philip C D Hobbs

Principal Consultant

ElectroOptical Innovations LLC / Hobbs ElectroOptics

Optics, Electro-optics, Photonics, Analog Electronics

Briarcliff Manor NY 10510

http://electrooptical.net

http://hobbs-eo.com

Guest

Mon Feb 11, 2019 5:45 pm

On Sat, 09 Feb 2019 20:26:30 +0200, upsidedown_at_downunder.com wrote:

On Sat, 09 Feb 2019 09:22:56 -0800, John Larkin

jjlarkin_at_highlandtechnology.com> wrote:

On Sat, 09 Feb 2019 17:52:12 +0200, upsidedown_at_downunder.com wrote:

On Sat, 9 Feb 2019 03:36:06 -0800 (PST), dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ?

Think about the Barkhausen criterion, the total loop gain must be

larger than 1 and the total phase around the loop must be correct.

At oscillator startup, there is always some amplifier input related

white thermal noise. The amplifier amplifies the noise G times. This

noise is them coupled back to the input via the frequency selective

network with quality Q with correct phase, thus a narrow band noise

with bandwidth f/Q is connected back to amplifier input. The noise is

amplified nearly to G² times and then running again through the filter

and having f/Q² bandwidth at amplifier input. During next iteration

the signal is amplified up to G³ and filtered again to f/Q³ and so on.

This continues, until the signal amplitude is limited by the available

voltage swing.

The small signal s-parameters are initially critical, since the

Barkhausen criterions must be satisfied from thermal noise levels up

to limiting.

If the amp's transfer function has the right (ie, wrong) shape you can

make an oscillator that will run but not start.

Biasing the amplifier into class-C and the oscillator will not

automatically start. Once started the amplification in class C will

kick the resonator once each cycle.

In practice, such oscillators may start by quickly applying the

operating voltage, which allows some collector current to flow

momentarily. You may end up with an oscillator, which starts nicely

when battery powered but not when mains powered through linear power

supply with big electrolytes . With such power supply, the voltage

may start too slowly to initiate the initial cycle.

jjlarkin_at_highlandtechnology.com> wrote:

On Sat, 09 Feb 2019 17:52:12 +0200, upsidedown_at_downunder.com wrote:

On Sat, 9 Feb 2019 03:36:06 -0800 (PST), dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ?

Think about the Barkhausen criterion, the total loop gain must be

larger than 1 and the total phase around the loop must be correct.

At oscillator startup, there is always some amplifier input related

white thermal noise. The amplifier amplifies the noise G times. This

noise is them coupled back to the input via the frequency selective

network with quality Q with correct phase, thus a narrow band noise

with bandwidth f/Q is connected back to amplifier input. The noise is

amplified nearly to G² times and then running again through the filter

and having f/Q² bandwidth at amplifier input. During next iteration

the signal is amplified up to G³ and filtered again to f/Q³ and so on.

This continues, until the signal amplitude is limited by the available

voltage swing.

The small signal s-parameters are initially critical, since the

Barkhausen criterions must be satisfied from thermal noise levels up

to limiting.

If the amp's transfer function has the right (ie, wrong) shape you can

make an oscillator that will run but not start.

Biasing the amplifier into class-C and the oscillator will not

automatically start. Once started the amplification in class C will

kick the resonator once each cycle.

In practice, such oscillators may start by quickly applying the

operating voltage, which allows some collector current to flow

momentarily. You may end up with an oscillator, which starts nicely

when battery powered but not when mains powered through linear power

supply with big electrolytes . With such power supply, the voltage

may start too slowly to initiate the initial cycle.

Instant-start oscillators are fun.

https://www.dropbox.com/s/0pldde09649579k/Burst_2.jpg?dl=0

The challenge is to make every cycle, including the first one, exactly

periodic.

--

John Larkin Highland Technology, Inc

lunatic fringe electronics

Guest

Mon Feb 11, 2019 7:45 pm

On Mon, 11 Feb 2019 10:30:48 -0500, Phil Hobbs

<pcdhSpamMeSenseless_at_electrooptical.net> wrote:

On 2/11/19 6:44 AM, dakupoto_at_gmail.com wrote:

On Saturday, February 9, 2019 at 7:50:43 AM UTC-5, Phil Hobbs wrote:

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's initially

in the small signal condition, so the resonator + small signal S params

have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

It depends on the type of oscillator one is looking at.

A differential oscillator, by its very nature, does not need any transistor biasing, and so it does not matter

if the S parameters are used or not.

In addition, for the new breed of transistors(e/g/.

HFA3134 from Renessas Semiconductor) the datasheet DOES NOT list ANY S parameters. With a fT of 8 GHz, it

would work very well in the RF - microwave frequency range.

Sure. It has a super-detailed SPICE model for both the device and the

package parasitics, which is going to be more useful than S parameters.

You can generate S parameters from the model, but going the other way is

a lot more complicated.

Cheers

Phil Hobbs

On Saturday, February 9, 2019 at 7:50:43 AM UTC-5, Phil Hobbs wrote:

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's initially

in the small signal condition, so the resonator + small signal S params

have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

It depends on the type of oscillator one is looking at.

A differential oscillator, by its very nature, does not need any transistor biasing, and so it does not matter

if the S parameters are used or not.

In addition, for the new breed of transistors(e/g/.

HFA3134 from Renessas Semiconductor) the datasheet DOES NOT list ANY S parameters. With a fT of 8 GHz, it

would work very well in the RF - microwave frequency range.

Sure. It has a super-detailed SPICE model for both the device and the

package parasitics, which is going to be more useful than S parameters.

You can generate S parameters from the model, but going the other way is

a lot more complicated.

Cheers

Phil Hobbs

Anything really interesting is going to be nonlinear, so may as well

Spice.

--

John Larkin Highland Technology, Inc

picosecond timing precision measurement

jlarkin att highlandtechnology dott com

http://www.highlandtechnology.com

Guest

Mon Feb 11, 2019 8:45 pm

Am 11.02.19 um 19:06 schrieb John Larkin:

On Mon, 11 Feb 2019 10:30:48 -0500, Phil Hobbs

pcdhSpamMeSenseless_at_electrooptical.net> wrote:

On 2/11/19 6:44 AM, dakupoto_at_gmail.com wrote:

On Saturday, February 9, 2019 at 7:50:43 AM UTC-5, Phil Hobbs wrote:

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's initially

in the small signal condition, so the resonator + small signal S params

have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

It depends on the type of oscillator one is looking at.

A differential oscillator, by its very nature, does not need any transistor biasing, and so it does not matter

if the S parameters are used or not.

In addition, for the new breed of transistors(e/g/.

HFA3134 from Renessas Semiconductor) the datasheet DOES NOT list ANY S parameters. With a fT of 8 GHz, it

would work very well in the RF - microwave frequency range.

Sure. It has a super-detailed SPICE model for both the device and the

package parasitics, which is going to be more useful than S parameters.

You can generate S parameters from the model, but going the other way is

a lot more complicated.

Cheers

Phil Hobbs

Anything really interesting is going to be nonlinear, so may as well

Spice.

pcdhSpamMeSenseless_at_electrooptical.net> wrote:

On 2/11/19 6:44 AM, dakupoto_at_gmail.com wrote:

On Saturday, February 9, 2019 at 7:50:43 AM UTC-5, Phil Hobbs wrote:

On 2/9/19 6:36 AM, dakupoto_at_gmail.com wrote:

Could some electronics guru here help clarify the following.

Small signal S parameter amalysis is based on small signal

levels and a linearized cirucuit, with a DC operating point(bias) condition.

Large signal S parameter extends this scheme to high power

operating conditions of non-linear devices, where the

assumptions of small signal do not hold. Large signal

S parameter scheme is based on harmonic balance, which

involves analyzing the signals in the frequency domain.

i.e., Forier transforms.

Both schemes use a 2 port network, with the signal entering

at the inpit("from") port and coming out at the output("to")

port.

With these in mind, what about oscillators ? These are

one port networks, with a 2 port component (amplifier)

in it. So are large and small signal S parameters

applicable to oscillators ? Amplifiers are ripe for

large signal S parameters. For that matter, are the S

parameters quoted for older RF|micrwave transistors

small or karge signal S parameters ?

All hints/suggestions are welcome. Thanks in advance.

The first thing an oscillator has to do is to start up. It's initially

in the small signal condition, so the resonator + small signal S params

have to be unstable. So you can't ignore them.

Gerhard knows more RF than I do, so I'll let him carry on. ;)

It depends on the type of oscillator one is looking at.

A differential oscillator, by its very nature, does not need any transistor biasing, and so it does not matter

if the S parameters are used or not.

In addition, for the new breed of transistors(e/g/.

HFA3134 from Renessas Semiconductor) the datasheet DOES NOT list ANY S parameters. With a fT of 8 GHz, it

would work very well in the RF - microwave frequency range.

Sure. It has a super-detailed SPICE model for both the device and the

package parasitics, which is going to be more useful than S parameters.

You can generate S parameters from the model, but going the other way is

a lot more complicated.

Cheers

Phil Hobbs

Anything really interesting is going to be nonlinear, so may as well

Spice.

Unfortunately, nonlinear analysis in Spice is quite meagre.

You just get transient analysis and that's it. OK, add FFT from

the post processor.

For noise and frequency response analysis, the circuit is linearized

around the operating point, so it is small signal only by definition.

No nonlinear noise, no harmonic balance, no large signal frequency response.

I would not get very far determining the noise characteristics of my

chopper amplifiers. How could it linearize the circuit in the presence

of the chopp clock and the continuous switching?

How do I determine the noise level of an amplifier that is near

compression? That is the normal case in the sustaining amplifier

of an oscillator.

How could I see the jitter induced by noise or self heating?

Transient simulation is noise free.

How do I simulate a SRD frequency multiplier? Cannot. There

is no concept of carrier lifetime in Spice. No PIN diodes.

Oh, 1N4007 is a PIN diode. (the others in the series aren't)

cheers,

Gerhard

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