Filter cap choice for ultra low ripple

Cursitor Doom · Aug 9, 2015

Gentlemen,

What is currently the best choice of filter capacitor for the PSU section
of a high-end signal generator the output of which (obviously) really
needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

Cursitor Doom · Aug 9, 2015

On Sun, 09 Aug 2015 11:09:01 -0400, DecadentLinuxUserNumeroUno wrote:

On Sun, 9 Aug 2015 14:27:50 +0000 (UTC), Cursitor Doom
curd@notformail.com> Gave us:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU
section of a high-end signal generator the output of which (obviously)
really needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

In general terms.... You're an idiot on par with SkyTard Belching.

Yeah, and you're a brainless troll with a long and very well-established
track record.

Phil Hobbs · Aug 9, 2015

If you can afford a volt or so of loss, a 2-stage cap multiplier is the ticket. You can get way over 120 dB rejection of SMPS frequencies.

Cheers

Phil Hobbs

Phil Hobbs · Aug 9, 2015

A "high end signal generator" would likely have a linear PS in it, not
a noisy SMPS.

But you should know that

Back in the day, that would have been the case. In the last 20 years or so, we've had to adapt, though, and cap multipliers are a huge part of that.

Many of my protos are powered by random laptop bricks via cap multipliers.

Cheers

Phil Hobbs

DecadentLinuxUserNumeroUn · Aug 9, 2015

On Sun, 9 Aug 2015 14:27:50 +0000 (UTC), Cursitor Doom
<curd@notformail.com> Gave us:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU section
of a high-end signal generator the output of which (obviously) really
needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

In general terms.... You're an idiot on par with SkyTard Belching.

John S · Aug 9, 2015

On 8/9/2015 9:27 AM, Cursitor Doom wrote:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU section
of a high-end signal generator the output of which (obviously) really
needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

Capacitance as large as humanly possible.

Spehro Pefhany · Aug 9, 2015

On Sun, 9 Aug 2015 14:27:50 +0000 (UTC), the renowned Cursitor Doom
<curd@notformail.com> wrote:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU section
of a high-end signal generator the output of which (obviously) really
needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

Roughly what frequency is the ripple at? Mains, 50kHz, 2MHz?

Polymer electrolytics are pretty good, as are ceramic caps. More
stages are better than fewer, and you can always use the cap
multiplier gambit. Regulators with few-uV RMS noise are available.

--sp

--
Best regards,
Spehro Pefhany
Amazon link for AoE 3rd Edition: http://tinyurl.com/ntrpwu8
Microchip link for 2015 Masters in Phoenix: http://tinyurl.com/l7g2k48

DecadentLinuxUserNumeroUn · Aug 9, 2015

On Sun, 9 Aug 2015 15:13:22 +0000 (UTC), Cursitor Doom
<curd@notformail.com> Gave us:

On Sun, 09 Aug 2015 11:09:01 -0400, DecadentLinuxUserNumeroUno wrote:

On Sun, 9 Aug 2015 14:27:50 +0000 (UTC), Cursitor Doom
curd@notformail.com> Gave us:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU
section of a high-end signal generator the output of which (obviously)
really needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

In general terms.... You're an idiot on par with SkyTard Belching.

Yeah, and you're a brainless troll

I am not a troll, and I have orders of magnitude more electronic
knowledge than you do.

with a long and very well-established
track record.

What's the matter, dumbfuck? Does the truth hurt?

Filtering ripple takes more than a simple "filter cap" or "filter cap
choice", you retarded putz.

You sport about the same 'intelligence' about electronics as Donald
Trump does on US history, or foreign policy or political posture. He is
an absolute idiot, and you are right there in the same class.

You and "a high end signal generator" are two things that are mutually
exclusive. So your grasp of what internals are needed in one are pretty
far apart as well.

Particularly if you are so dumb (in electronics)that you need to come
in here and ask such a question, which reveals just how ill equipped you
are for completing any such design task.

And as far as my "track record" goes, it only puts the pinch on abject
idiots such as yourself.

Go somewhere else and spread your stench.

In here you are transparent, and you asking such a low end, poorly
worded revealing question makes you quite transparent, and obviously not
equipped to tackle such a complex design as a "high end signal
generator".

So yeah, punk... you are on par with the SkyTard, who has been
invading several newsgroups with his utter stupidity.

And that is despite the fact that your question is on topic here. It
simply exposes such how simple your skill level is. Quit while you are
ahead., or your 'ultra low' profile of stupidity will get raised.
ooops... too late.

rickman · Aug 9, 2015

On 8/9/2015 10:27 AM, Cursitor Doom wrote:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU section
of a high-end signal generator the output of which (obviously) really
needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

Ripple is determined by two factors. One is the capacitance relative to
the amount of ripple current flowing and the frequency. The other is
the ESR of the cap relative to the peak current.

Ceramic caps have the lowest ESR of caps commonly used for PSU outputs.
Electrolytic caps provide more capacitance at a lower price.
Sometimes the best tradeoff is a combination, other times ceramic caps
alone will do the job well enough. The only ways to know are to do the
calculations or to build it both ways and measure the ripple.

--

Rick

Jim Thompson · Aug 9, 2015

On Sun, 9 Aug 2015 15:13:22 +0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

On Sun, 09 Aug 2015 11:09:01 -0400, DecadentLinuxUserNumeroUno wrote:

On Sun, 9 Aug 2015 14:27:50 +0000 (UTC), Cursitor Doom
curd@notformail.com> Gave us:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU
section of a high-end signal generator the output of which (obviously)
really needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

In general terms.... You're an idiot on par with SkyTard Belching.

Yeah, and you're a brainless troll with a long and very well-established
track record.

Doesn't Pan offer filtering? In Agent I just killfile DecadentLoser
so that I'm not exposed to his (or other loser's

rants.... keeps
me calm and my blood pressure low >:-}

The only time I see his rants is when you feed the troll :-(

...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: skypeanalog | |
| Voice

Pomegranate Bastard · Aug 9, 2015

On Sun, 09 Aug 2015 11:31:04 -0400, DecadentLinuxUserNumeroUno
<DLU1@DecadentLinuxUser.org> wrote:

On Sun, 9 Aug 2015 15:13:22 +0000 (UTC), Cursitor Doom
curd@notformail.com> Gave us:

On Sun, 09 Aug 2015 11:09:01 -0400, DecadentLinuxUserNumeroUno wrote:

On Sun, 9 Aug 2015 14:27:50 +0000 (UTC), Cursitor Doom
curd@notformail.com> Gave us:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU
section of a high-end signal generator the output of which (obviously)
really needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

In general terms.... You're an idiot on par with SkyTard Belching.

Yeah, and you're a brainless troll

I am not a troll, and I have orders of magnitude more electronic
knowledge than you do.

You are an imbecile.

with a long and very well-established
track record.

What's the matter, dumbfuck? Does the truth hurt?

Filtering ripple takes more than a simple "filter cap" or "filter cap
choice", you retarded putz.

You sport about the same 'intelligence' about electronics as Donald
Trump does on US history, or foreign policy or political posture. He is
an absolute idiot, and you are right there in the same class.

You and "a high end signal generator" are two things that are mutually
exclusive. So your grasp of what internals are needed in one are pretty
far apart as well.

Particularly if you are so dumb (in electronics)that you need to come
in here and ask such a question, which reveals just how ill equipped you
are for completing any such design task.

And as far as my "track record" goes, it only puts the pinch on abject
idiots such as yourself.

Go somewhere else and spread your stench.

In here you are transparent, and you asking such a low end, poorly
worded revealing question makes you quite transparent, and obviously not
equipped to tackle such a complex design as a "high end signal
generator".

So yeah, punk... you are on par with the SkyTard, who has been
invading several newsgroups with his utter stupidity.

And that is despite the fact that your question is on topic here. It
simply exposes such how simple your skill level is. Quit while you are
ahead., or your 'ultra low' profile of stupidity will get raised.
ooops... too late.

DecadentLinuxUserNumeroUn · Aug 9, 2015

On Sun, 09 Aug 2015 08:50:41 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> Gave us:

On Sun, 9 Aug 2015 15:13:22 +0000 (UTC), Cursitor Doom
curd@notformail.com> wrote:

On Sun, 09 Aug 2015 11:09:01 -0400, DecadentLinuxUserNumeroUno wrote:

On Sun, 9 Aug 2015 14:27:50 +0000 (UTC), Cursitor Doom
curd@notformail.com> Gave us:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU
section of a high-end signal generator the output of which (obviously)
really needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

In general terms.... You're an idiot on par with SkyTard Belching.

Yeah, and you're a brainless troll with a long and very well-established
track record.

Doesn't Pan offer filtering? In Agent I just killfile DecadentLoser
so that I'm not exposed to his (or other loser's rants.... keeps
me calm and my blood pressure low >:-}

The only time I see his rants is when you feed the troll :-(

...Jim Thompson

There was no rant, you absolutely retarded fuck.

DecadentLinuxUserNumeroUn · Aug 9, 2015

On Sun, 9 Aug 2015 09:03:07 -0700 (PDT), Phil Hobbs <pcdhobbs@gmail.com>
Gave us:

If you can afford a volt or so of loss, a 2-stage cap multiplier is the ticket. You can get way over 120 dB rejection of SMPS frequencies.

Cheers

Phil Hobbs

A "high end signal generator" would likely have a linear PS in it, not
a noisy SMPS.

But you should know that, Phil.

DecadentLinuxUserNumeroUn · Aug 9, 2015

On Sun, 09 Aug 2015 17:07:46 +0100, Pomegranate Bastard
<PommyB@dsl.pipex.com> Gave us:

>You are an imbecile.

Fuck off and die, pommy bitch cock sucking retard.

David Brown · Aug 9, 2015

On 09/08/15 16:27, Cursitor Doom wrote:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU section
of a high-end signal generator the output of which (obviously) really
needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

Decadent Linux may be extraordinarily rude, but he is right that there
is no answer to this question - we would need a lot more details to give
useful answers. Of particular importance are the frequency of noise to
be rejected, the type of currents and voltages involved, any unusual
circumstances or restrictions (such as wanting to be as small as
possible), and some information about the rest of the PSU design.

And a capacitor alone does not make a filter - you need it in
combination with something else (an inductance or resistance), and
usually in multiple stages with multiple filter components.

With that information, someone should be able to give you more helpful
answers. (Not me, probably - it's not really my field.)

DecadentLinuxUserNumeroUn · Aug 9, 2015

On Sun, 09 Aug 2015 19:25:14 +0200, David Brown
<david.brown@hesbynett.no> Gave us:

On 09/08/15 16:27, Cursitor Doom wrote:
Gentlemen,

What is currently the best choice of filter capacitor for the PSU section
of a high-end signal generator the output of which (obviously) really
needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

Decadent Linux may be extraordinarily rude, but he is right that there
is no answer to this question - we would need a lot more details to give
useful answers. Of particular importance are the frequency of noise to
be rejected, the type of currents and voltages involved, any unusual
circumstances or restrictions (such as wanting to be as small as
possible), and some information about the rest of the PSU design.

And a capacitor alone does not make a filter - you need it in
combination with something else (an inductance or resistance), and
usually in multiple stages with multiple filter components.

With that information, someone should be able to give you more helpful
answers. (Not me, probably - it's not really my field.)

The term for the day is "envelope tracking".

Not a postal service term.

joe hey · Aug 10, 2015

On Sun, 09 Aug 2015 12:58:30 -0400, DecadentLinuxUserNumeroUno wrote:

On Sun, 09 Aug 2015 17:07:46 +0100, Pomegranate Bastard
PommyB@dsl.pipex.com> Gave us:

You are an imbecile.

Fuck off and die, pommy bitch cock sucking retard.

Jesus Christ, this guy really goes nuking around for even the slightest
of reasons...

joe (quickly hiding in the cabinet)

joe hey · Aug 10, 2015

On Sun, 09 Aug 2015 13:40:35 -0400, DecadentLinuxUserNumeroUno wrote:

On Sun, 09 Aug 2015 19:25:14 +0200, David Brown
david.brown@hesbynett.no> Gave us:

On 09/08/15 16:27, Cursitor Doom wrote:
Gentlemen,

What is currently the best choice of filter capacitor for the PSU
section of a high-end signal generator the output of which (obviously)
really needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

Decadent Linux may be extraordinarily rude,

(O.T.)

He reminds me of a quite (electronically) brilliant Finnish guy who got
poisoned from his mercury amalgam fillings, became 'as mad as a hatter',
tried to sue the (Finnish) government and the medical establishment, did
probably some other things wrong too, and finally had to leave the
country due to harassment/persecution and went to the USA with his
electronics knowledge, where he continued ranting around where and
whenever he got the opportunity and at the slightest provocation.

It seems that mercury poisoning does that to your brain/constitution.

joe

but he is right that there
is no answer to this question - we would need a lot more details to give
useful answers. Of particular importance are the frequency of noise to
be rejected, the type of currents and voltages involved, any unusual
circumstances or restrictions (such as wanting to be as small as
possible), and some information about the rest of the PSU design.

And a capacitor alone does not make a filter - you need it in
combination with something else (an inductance or resistance), and
usually in multiple stages with multiple filter components.

With that information, someone should be able to give you more helpful
answers. (Not me, probably - it's not really my field.)

The term for the day is "envelope tracking".

Not a postal service term.

John Larkin · Aug 10, 2015

On Sun, 9 Aug 2015 14:27:50 +0000 (UTC), Cursitor Doom
<curd@notformail.com> wrote:

Gentlemen,

What is currently the best choice of filter capacitor for the PSU section
of a high-end signal generator the output of which (obviously) really
needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

Generally one buys enough filter cap to get the ripple down to maybe 1
volt p-p, then adds a regulator to stabilize the voltage and greatly
reduce ripple. A second regulator or c-multiplier can be used to
further reduce noise and ripple, to power the more sensitive signal
generator stages.

--

John Larkin Highland Technology, Inc
lunatic fringe electronics

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

Tim Williams · Aug 10, 2015

Best?

All things considered, same as always, electrolytic. Low cost, high value,
moderate to low ESR, reasonable life (when not run hot).

For any other considerations, it's up to you. Cost? Operating frequency?
Size? General *considerations*, yes, but no generalized *conclusion*.
That's what us designers get paid for. ;-)

Even more generally, however: you seem to dismiss system-level
considerations as obvious! But no, a signal generator is a system. The
power supply only needs to be as well-filtered as the PSRR of the output
stage, preamps and such require for the desired output noise level. And if
there's a regulator stage in there as well, even less (primary) filtering is
needed.

And you can locally filter and regulate stages that are unusually sensitive,
or rebuild them in terms of ratios and ground-referenced voltages, to
increase their PSRR.

There should be absolutely no excuse for excruciatingly clean DC, not since
tubes have gone the way of the dodo. Complementary semiconductors (and good
constant current characteristics) free us from the burden of B+ referenced
signals and low PSRR.

Tim

--
Seven Transistor Labs
Electrical Engineering Consultation
Website: http://seventransistorlabs.com

"Cursitor Doom" <curd@notformail.com> wrote in message
news:mq7o16$suq$1@dont-email.me...

Gentlemen,

What is currently the best choice of filter capacitor for the PSU section
of a high-end signal generator the output of which (obviously) really
needs to be as ripple-free as humanly possible?
Just in *GENERAL* terms, please guys; don't want to get bogged down in
specifics and calculations at this stage, please!

tia,
cd

Filter cap choice for ultra low ripple

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