elektroda.net NewsGroups Forum Index - Electronics Design - class c rf amp with bfr93a
JosephKK
Guest
Guest
Wed Sep 01, 2010 5:40 am
On Mon, 30 Aug 2010 08:52:09 -0700, Joerg <invalid_at_invalid.invalid>
wrote:
Quote:
Fred Abse wrote:
On Sun, 29 Aug 2010 16:41:26 -0700, Joerg wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 15:21:15 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 13:51:14 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Fred Abse wrote:
On Sat, 28 Aug 2010 14:34:24 -0700, Fred Abse wrote:
Sunday's exercise might be to compare the (Philips) model's S-parameters
against Philips' data sheet values. Wanna bet they don't match?
Pretty close match, apart from S22, which doesn't show the pronounced kink
shown in the datasheet.
Shame LTSpice won't do polar plots. Since it does impedance and
S-params, it really ought to.
Found a way round that. Set LTSpice to do ASCII rawfiles, run, edit two or
three LT-specific lines out of the rawfile, and load it into Berkeley
Spice 3f4's Nutmeg, then plot polar and Smith from there.
Much easier than trying to get LTSpice netlists to run in 3f4.
I still think the facility should be in LTSpice, though.
I think Jim Thompson once mentioned a software that could render raw
data into all sorts of graphics including polar. Jim?
Scratching head... I don't remember
I believe it was a software that you could also throw scanned in plots.
Aha! I did recently buy "GetData Graph Digitizer" which can create
numerical data points from graphs in data sheets.
Handy for creating subcircuits when all you have is a data sheet.
Reverse engineering ... ?
PSpice can do about any x-y plot you'd like, but I don't know how
you'd do polar except with some innovative macros
I think LTSpice can output polar data but I have never done it. I
believe the command is "meascplxfmt polar".
Can't find any reference. .meas statements usually start with an analysis
type, like ac, tran, etc.
Polar plots uploaded to a.b.s.e. Unfortunately my hand-added annotations
of frequency end points haven't survived the upload. Added in gimp,
they're present in the .pngs here.
Can't access a.b.s.e. :-(
Falk Willberg from a German NG has set up his own news server with
binary access but that would require everyone who wants to look to have
the access info (which Falk freely gives out to anyone who requests it).
On Sun, 29 Aug 2010 16:41:26 -0700, Joerg wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 15:21:15 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 13:51:14 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Fred Abse wrote:
On Sat, 28 Aug 2010 14:34:24 -0700, Fred Abse wrote:
Sunday's exercise might be to compare the (Philips) model's S-parameters
against Philips' data sheet values. Wanna bet they don't match?
Pretty close match, apart from S22, which doesn't show the pronounced kink
shown in the datasheet.
Shame LTSpice won't do polar plots. Since it does impedance and
S-params, it really ought to.
Found a way round that. Set LTSpice to do ASCII rawfiles, run, edit two or
three LT-specific lines out of the rawfile, and load it into Berkeley
Spice 3f4's Nutmeg, then plot polar and Smith from there.
Much easier than trying to get LTSpice netlists to run in 3f4.
I still think the facility should be in LTSpice, though.
I think Jim Thompson once mentioned a software that could render raw
data into all sorts of graphics including polar. Jim?
Scratching head... I don't remember
I believe it was a software that you could also throw scanned in plots.
Aha! I did recently buy "GetData Graph Digitizer" which can create
numerical data points from graphs in data sheets.
Handy for creating subcircuits when all you have is a data sheet.
Reverse engineering ... ?
PSpice can do about any x-y plot you'd like, but I don't know how
you'd do polar except with some innovative macros
I think LTSpice can output polar data but I have never done it. I
believe the command is "meascplxfmt polar".
Can't find any reference. .meas statements usually start with an analysis
type, like ac, tran, etc.
Polar plots uploaded to a.b.s.e. Unfortunately my hand-added annotations
of frequency end points haven't survived the upload. Added in gimp,
they're present in the .pngs here.
Can't access a.b.s.e. :-(
Falk Willberg from a German NG has set up his own news server with
binary access but that would require everyone who wants to look to have
the access info (which Falk freely gives out to anyone who requests it).
Cool. Thanks Falk.
JosephKK
Guest
Guest
Wed Sep 01, 2010 5:51 am
On Tue, 31 Aug 2010 10:17:21 -0700, Fred Abse
<excretatauris_at_invalid.invalid> wrote:
Quote:
On Mon, 30 Aug 2010 09:20:34 -0700, Joerg wrote:
Just a word of caution here: Don't do this for a design that has to go
into mass production. The capacitive device parameters are lot dependent
and vary with temperature.
Fortunately. there's always a bit of wiggle room, plus, my designs are
never more than a few hundred off.
I leave mass produced stuff to those with the relevant mindset (ITCFWI)
^^^^^^ Not found. Please persplain.
Just a word of caution here: Don't do this for a design that has to go
into mass production. The capacitive device parameters are lot dependent
and vary with temperature.
Fortunately. there's always a bit of wiggle room, plus, my designs are
never more than a few hundred off.
I leave mass produced stuff to those with the relevant mindset (ITCFWI)
^^^^^^ Not found. Please persplain.
neddie
Guest
Guest
Wed Sep 01, 2010 1:50 pm
On Aug 30, 6:02 pm, Fred Abse <excretatau...@invalid.invalid> wrote:
Quote:
On Mon, 30 Aug 2010 06:29:37 -0700, neddie wrote:
Hi there.
Where did you get the input impadance of 300+j76 ohms from.
From an LTSpice simulation of the circuit, using an .ac analysis with a
.net directive.
Can you get it from LTSpice , or do you have a datasheet that shows
that.
I can't find it on the datasheet that I have. They do have a S11
plot , but it does
show anything like that. Maybe I'm just being a dumbo. A distinct
possability :0)
The S-param plots are for the device alone. The model gets near(ish) the
measured values in the datasheet (assuming they *are* measured!), but I'd
say no cigar.
Same for the collector impedance of 700 ohms.How do you get
it?
It's not the looking-backwards collector impedance, that's more or less
irrelevant, despite what some people would have you believe. Forget
maximum power transfer theorem (Joerg has anecdotes about that, and his
onetime Prof).
700 ohms is the load that happens to give about 50mW in this case, using a
Vcc of 6V.
The usual rule of thumb is:
Rl=Vcc^2/(2*Pout), for a class C amplifier.
This can be out by quite a lot, depending on other factors, but it's a
start. In fact, it gives 360 ohms, which gives about 100mW in this case,
so I throttled it back.
The design procedure I use is this:
Select the collector feed inductor to resonate with the device output
capacitance.
Determine what load resistance will result in the desired power.
Design a network to match that resistance to your desired load, with your
desired Q, usually about 10, any more and tuning gets difficult. Much
less, and harmonics become a problem.
Unfortunately, stepping up 200 ohms to 700 ohms at Q=10, using a simple RL
network results in practically unrealizable capacitance values, so my
circuit isn't much use outside of a theoretical simulation.
Why 200 ohms, BTW?
Here's the circuit, for what it's worth (not much).
Version 4
SHEET 1 1300 2476
WIRE 48 144 -256 144
WIRE -256 192 -256 144
WIRE 48 192 48 144
WIRE -256 304 -256 272
WIRE -224 304 -256 304
WIRE -96 304 -160 304
WIRE -48 304 -96 304
WIRE 64 304 32 304
WIRE 192 304 128 304
WIRE -256 320 -256 304
WIRE 192 320 192 304
WIRE -96 352 -96 304
WIRE -464 368 -672 368
WIRE -352 368 -400 368
WIRE -320 368 -352 368
WIRE -352 384 -352 368
WIRE -672 480 -672 448
WIRE -368 480 -672 480
WIRE -352 480 -352 464
WIRE -352 480 -368 480
WIRE -256 480 -256 416
WIRE -256 480 -352 480
WIRE -96 480 -96 432
WIRE -96 480 -256 480
WIRE 48 480 48 272
WIRE 48 480 -96 480
WIRE 192 480 192 400
WIRE 192 480 48 480
WIRE -368 496 -368 480
FLAG -368 496 0
FLAG 48 480 0
SYMBOL voltage -672 352 R0
WINDOW 3 32 84 Left 0
WINDOW 123 -97 53 Left 0
WINDOW 39 24 44 Left 0
SYMATTR Value SINE(0 3 433meg)
SYMATTR Value2 AC 1
SYMATTR SpiceLine Rser=50
SYMATTR InstName V1
SYMBOL ind -272 176 R0
SYMATTR InstName L1
SYMATTR Value 190n
SYMBOL voltage 48 176 R0
SYMATTR InstName V2
SYMATTR Value 6
SYMBOL npn2 -320 320 R0
SYMATTR InstName Q1
SYMATTR Value BFR93A
SYMATTR Prefix X
SYMBOL ind -368 368 R0
SYMATTR InstName L2
SYMATTR Value 47n
SYMBOL res 176 304 R0
SYMATTR InstName R1
SYMATTR Value 200
SYMBOL ind -64 288 M90
WINDOW 0 5 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName L3
SYMATTR Value 597.5n
SYMBOL cap 128 288 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C1
SYMATTR Value 0.18p
SYMBOL ind -112 336 R0
SYMATTR InstName L4
SYMATTR Value 137.5n
SYMBOL cap -224 288 M90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value .8p
SYMBOL cap -400 352 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C3
SYMATTR Value 1n
TEXT -552 280 Left 0 !.tran 0 60n 10n 100p
TEXT -160 536 Left 0 !.lib BFR93A.sub
TEXT -408 536 Left 0 !;.net I(R1) V1
TEXT -872 280 Left 0 !;ac dec 1000 350e6 550e6
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
Hi there.
Where did you get the input impadance of 300+j76 ohms from.
From an LTSpice simulation of the circuit, using an .ac analysis with a
.net directive.
Can you get it from LTSpice , or do you have a datasheet that shows
that.
I can't find it on the datasheet that I have. They do have a S11
plot , but it does
show anything like that. Maybe I'm just being a dumbo. A distinct
possability :0)
The S-param plots are for the device alone. The model gets near(ish) the
measured values in the datasheet (assuming they *are* measured!), but I'd
say no cigar.
Same for the collector impedance of 700 ohms.How do you get
it?
It's not the looking-backwards collector impedance, that's more or less
irrelevant, despite what some people would have you believe. Forget
maximum power transfer theorem (Joerg has anecdotes about that, and his
onetime Prof).
700 ohms is the load that happens to give about 50mW in this case, using a
Vcc of 6V.
The usual rule of thumb is:
Rl=Vcc^2/(2*Pout), for a class C amplifier.
This can be out by quite a lot, depending on other factors, but it's a
start. In fact, it gives 360 ohms, which gives about 100mW in this case,
so I throttled it back.
The design procedure I use is this:
Select the collector feed inductor to resonate with the device output
capacitance.
Determine what load resistance will result in the desired power.
Design a network to match that resistance to your desired load, with your
desired Q, usually about 10, any more and tuning gets difficult. Much
less, and harmonics become a problem.
Unfortunately, stepping up 200 ohms to 700 ohms at Q=10, using a simple RL
network results in practically unrealizable capacitance values, so my
circuit isn't much use outside of a theoretical simulation.
Why 200 ohms, BTW?
Here's the circuit, for what it's worth (not much).
Version 4
SHEET 1 1300 2476
WIRE 48 144 -256 144
WIRE -256 192 -256 144
WIRE 48 192 48 144
WIRE -256 304 -256 272
WIRE -224 304 -256 304
WIRE -96 304 -160 304
WIRE -48 304 -96 304
WIRE 64 304 32 304
WIRE 192 304 128 304
WIRE -256 320 -256 304
WIRE 192 320 192 304
WIRE -96 352 -96 304
WIRE -464 368 -672 368
WIRE -352 368 -400 368
WIRE -320 368 -352 368
WIRE -352 384 -352 368
WIRE -672 480 -672 448
WIRE -368 480 -672 480
WIRE -352 480 -352 464
WIRE -352 480 -368 480
WIRE -256 480 -256 416
WIRE -256 480 -352 480
WIRE -96 480 -96 432
WIRE -96 480 -256 480
WIRE 48 480 48 272
WIRE 48 480 -96 480
WIRE 192 480 192 400
WIRE 192 480 48 480
WIRE -368 496 -368 480
FLAG -368 496 0
FLAG 48 480 0
SYMBOL voltage -672 352 R0
WINDOW 3 32 84 Left 0
WINDOW 123 -97 53 Left 0
WINDOW 39 24 44 Left 0
SYMATTR Value SINE(0 3 433meg)
SYMATTR Value2 AC 1
SYMATTR SpiceLine Rser=50
SYMATTR InstName V1
SYMBOL ind -272 176 R0
SYMATTR InstName L1
SYMATTR Value 190n
SYMBOL voltage 48 176 R0
SYMATTR InstName V2
SYMATTR Value 6
SYMBOL npn2 -320 320 R0
SYMATTR InstName Q1
SYMATTR Value BFR93A
SYMATTR Prefix X
SYMBOL ind -368 368 R0
SYMATTR InstName L2
SYMATTR Value 47n
SYMBOL res 176 304 R0
SYMATTR InstName R1
SYMATTR Value 200
SYMBOL ind -64 288 M90
WINDOW 0 5 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName L3
SYMATTR Value 597.5n
SYMBOL cap 128 288 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C1
SYMATTR Value 0.18p
SYMBOL ind -112 336 R0
SYMATTR InstName L4
SYMATTR Value 137.5n
SYMBOL cap -224 288 M90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C2
SYMATTR Value .8p
SYMBOL cap -400 352 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName C3
SYMATTR Value 1n
TEXT -552 280 Left 0 !.tran 0 60n 10n 100p
TEXT -160 536 Left 0 !.lib BFR93A.sub
TEXT -408 536 Left 0 !;.net I(R1) V1
TEXT -872 280 Left 0 !;ac dec 1000 350e6 550e6
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
Hi there.
With regards to the ltspice cct. What does the .net directive give
you. It just produces a netlist , or am I missing something.
I've managed to get an impedance plot using the ac analysis and
plotting V/I. That gives me the impedance in polar form , which is
great. I sometimes get a odd number like when I convert a number like
200 < -170 ( < , I can't draw the angel sign) , gives me -196 -j34.7
Somewhere in the back of my mind , from years ago , I remember
subtracting the angle (-170 in this cage) from 180degrees , if it is
bigger
than 90, or something like that. That gives me 196 - j34. So I assume
I'm on the right track. I've done some searching on polar to
rectangular conversion , but I can't seem to find anything about
this>? I must be missing something again :0(
I did a new track layout and remoddeled it in Sonnet. It gives me an
impedance of 5.5 +j28 ohms for the impedance at 433Mhz. Much easier to
match. Q is only
about 4 , but it's a start.
This rf stuff is tough , especially if it is not something you do
often :0(
Joerg
Guest
Guest
Wed Sep 01, 2010 3:47 pm
JosephKK wrote:
Quote:
On Mon, 30 Aug 2010 08:52:09 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Fred Abse wrote:
On Sun, 29 Aug 2010 16:41:26 -0700, Joerg wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 15:21:15 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 13:51:14 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Fred Abse wrote:
On Sat, 28 Aug 2010 14:34:24 -0700, Fred Abse wrote:
Sunday's exercise might be to compare the (Philips) model's S-parameters
against Philips' data sheet values. Wanna bet they don't match?
Pretty close match, apart from S22, which doesn't show the pronounced kink
shown in the datasheet.
Shame LTSpice won't do polar plots. Since it does impedance and
S-params, it really ought to.
Found a way round that. Set LTSpice to do ASCII rawfiles, run, edit two or
three LT-specific lines out of the rawfile, and load it into Berkeley
Spice 3f4's Nutmeg, then plot polar and Smith from there.
Much easier than trying to get LTSpice netlists to run in 3f4.
I still think the facility should be in LTSpice, though.
I think Jim Thompson once mentioned a software that could render raw
data into all sorts of graphics including polar. Jim?
Scratching head... I don't remember
I believe it was a software that you could also throw scanned in plots.
Aha! I did recently buy "GetData Graph Digitizer" which can create
numerical data points from graphs in data sheets.
Handy for creating subcircuits when all you have is a data sheet.
Reverse engineering ... ?
PSpice can do about any x-y plot you'd like, but I don't know how
you'd do polar except with some innovative macros
I think LTSpice can output polar data but I have never done it. I
believe the command is "meascplxfmt polar".
Can't find any reference. .meas statements usually start with an analysis
type, like ac, tran, etc.
Polar plots uploaded to a.b.s.e. Unfortunately my hand-added annotations
of frequency end points haven't survived the upload. Added in gimp,
they're present in the .pngs here.
Can't access a.b.s.e. :-(
Falk Willberg from a German NG has set up his own news server with
binary access but that would require everyone who wants to look to have
the access info (which Falk freely gives out to anyone who requests it).
Cool. Thanks Falk.
wrote:
Fred Abse wrote:
On Sun, 29 Aug 2010 16:41:26 -0700, Joerg wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 15:21:15 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 13:51:14 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Fred Abse wrote:
On Sat, 28 Aug 2010 14:34:24 -0700, Fred Abse wrote:
Sunday's exercise might be to compare the (Philips) model's S-parameters
against Philips' data sheet values. Wanna bet they don't match?
Pretty close match, apart from S22, which doesn't show the pronounced kink
shown in the datasheet.
Shame LTSpice won't do polar plots. Since it does impedance and
S-params, it really ought to.
Found a way round that. Set LTSpice to do ASCII rawfiles, run, edit two or
three LT-specific lines out of the rawfile, and load it into Berkeley
Spice 3f4's Nutmeg, then plot polar and Smith from there.
Much easier than trying to get LTSpice netlists to run in 3f4.
I still think the facility should be in LTSpice, though.
I think Jim Thompson once mentioned a software that could render raw
data into all sorts of graphics including polar. Jim?
Scratching head... I don't remember
I believe it was a software that you could also throw scanned in plots.
Aha! I did recently buy "GetData Graph Digitizer" which can create
numerical data points from graphs in data sheets.
Handy for creating subcircuits when all you have is a data sheet.
Reverse engineering ... ?
PSpice can do about any x-y plot you'd like, but I don't know how
you'd do polar except with some innovative macros
I think LTSpice can output polar data but I have never done it. I
believe the command is "meascplxfmt polar".
Can't find any reference. .meas statements usually start with an analysis
type, like ac, tran, etc.
Polar plots uploaded to a.b.s.e. Unfortunately my hand-added annotations
of frequency end points haven't survived the upload. Added in gimp,
they're present in the .pngs here.
Can't access a.b.s.e. :-(
Falk Willberg from a German NG has set up his own news server with
binary access but that would require everyone who wants to look to have
the access info (which Falk freely gives out to anyone who requests it).
Cool. Thanks Falk.
If you want access you can request it from Falk at:
nntp at consult42 dot com
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Fred Abse
Guest
Guest
Thu Sep 02, 2010 6:34 pm
On Tue, 31 Aug 2010 21:51:51 -0700, JosephKK wrote:
Quote:
On Tue, 31 Aug 2010 10:17:21 -0700, Fred Abse
excretatauris_at_invalid.invalid> wrote:
On Mon, 30 Aug 2010 09:20:34 -0700, Joerg wrote:
Just a word of caution here: Don't do this for a design that has to go
into mass production. The capacitive device parameters are lot dependent
and vary with temperature.
Fortunately. there's always a bit of wiggle room, plus, my designs are
never more than a few hundred off.
I leave mass produced stuff to those with the relevant mindset (ITCFWI)
^^^^^^ Not found. Please persplain.
excretatauris_at_invalid.invalid> wrote:
On Mon, 30 Aug 2010 09:20:34 -0700, Joerg wrote:
Just a word of caution here: Don't do this for a design that has to go
into mass production. The capacitive device parameters are lot dependent
and vary with temperature.
Fortunately. there's always a bit of wiggle room, plus, my designs are
never more than a few hundred off.
I leave mass produced stuff to those with the relevant mindset (ITCFWI)
^^^^^^ Not found. Please persplain.
If The Cap Fits, Wear It
;-)
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
Fred Abse
Guest
Guest
Thu Sep 02, 2010 6:34 pm
On Wed, 01 Sep 2010 03:50:11 -0700, neddie wrote:
Quote:
Hi there.
With regards to the ltspice cct. What does the .net directive give
you. It just produces a netlist , or am I missing something.
With regards to the ltspice cct. What does the .net directive give
you. It just produces a netlist , or am I missing something.
First, you need to uncomment the .net card, and uncomment the .ac card.
You'll get a barf about two analyses at once, so pick the .ac one. Run the
analysis, then from the plot screen, take a look at "Visible Traces".
You'll see that there are a few more than usual for an .ac analysis, nice
things like S-params, Y-params, and Z-params. You plot these as you would
anything else, using whatever format suits best - Bode, Nyquist, or
Cartesian.
Now, go RTFM to see how it all works, then load up
/examples/Educational/S-param.asc to get a feel for it.
Quote:
I've managed to get an impedance plot using the ac analysis and
plotting V/I. That gives me the impedance in polar form , which is
great. I sometimes get a odd number like when I convert a number like
200 < -170 ( < , I can't draw the angel sign)
plotting V/I. That gives me the impedance in polar form , which is
great. I sometimes get a odd number like when I convert a number like
200 < -170 ( < , I can't draw the angel sign)
How many angles can dance on the head of a pin ;-)
Quote:
, gives me -196 -j34.7
Somewhere in the back of my mind , from years ago , I remember
subtracting the angle (-170 in this cage) from 180degrees , if it is
bigger
than 90, or something like that. That gives me 196 - j34. So I assume
I'm on the right track. I've done some searching on polar to
rectangular conversion , but I can't seem to find anything about
this>? I must be missing something again :0(
Somewhere in the back of my mind , from years ago , I remember
subtracting the angle (-170 in this cage) from 180degrees , if it is
bigger
than 90, or something like that. That gives me 196 - j34. So I assume
I'm on the right track. I've done some searching on polar to
rectangular conversion , but I can't seem to find anything about
this>? I must be missing something again :0(
I find it difficult to believe that someone who has Sonnet, doesn't have a
calculator that does polar/rectangular conversions :-)
Quote:
I did a new track layout and remoddeled it in Sonnet. It gives me an
impedance of 5.5 +j28 ohms for the impedance at 433Mhz. Much easier to
match.
impedance of 5.5 +j28 ohms for the impedance at 433Mhz. Much easier to
match.
Much harder to match. Notwitstanding that losses in inductors and tracks are
starting to look significant, stepping up 5 ohms to the value you'll need
for 10mW at a reasonable Q is probably not feasible. I'd go with Joerg's
idea, and forget class C, use straight class A (who cares about efficiency,
it's only 10mW?). That also gives you the option of setting output power
by adjusting drive with a couple of resistors.
Quote:
Q is only
about 4 , but it's a start.
about 4 , but it's a start.
Not high enuf. Harmonics will not be nice. You'll need filtering, I was
getting -20dB on second harmonic with Q~~10. I don't know the spec. but at
20dB down on 10mW (100uW), you might get away without additional filtering.
Quote:
This rf
stuff is tough , especially if it is not something you do often :0(
stuff is tough , especially if it is not something you do often :0(
--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)
Joerg
Guest
Guest
Thu Sep 02, 2010 10:38 pm
Fred Abse wrote:
Quote:
On Tue, 31 Aug 2010 21:51:51 -0700, JosephKK wrote:
On Tue, 31 Aug 2010 10:17:21 -0700, Fred Abse
excretatauris_at_invalid.invalid> wrote:
On Mon, 30 Aug 2010 09:20:34 -0700, Joerg wrote:
Just a word of caution here: Don't do this for a design that has to go
into mass production. The capacitive device parameters are lot dependent
and vary with temperature.
Fortunately. there's always a bit of wiggle room, plus, my designs are
never more than a few hundred off.
I leave mass produced stuff to those with the relevant mindset (ITCFWI)
^^^^^^ Not found. Please persplain.
If The Cap Fits, Wear It
;-)
On Tue, 31 Aug 2010 10:17:21 -0700, Fred Abse
excretatauris_at_invalid.invalid> wrote:
On Mon, 30 Aug 2010 09:20:34 -0700, Joerg wrote:
Just a word of caution here: Don't do this for a design that has to go
into mass production. The capacitive device parameters are lot dependent
and vary with temperature.
Fortunately. there's always a bit of wiggle room, plus, my designs are
never more than a few hundred off.
I leave mass produced stuff to those with the relevant mindset (ITCFWI)
^^^^^^ Not found. Please persplain.
If The Cap Fits, Wear It
;-)
That would be for the engineering side of business. I once heard a
similar word of wisdom for the business side of business, and almost
spewed my coffee all over the place: Find a parade and get in front of
it :-)
--
Regards, Joerg
http://www.analogconsultants.com/
"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Jim Thompson
Guest
Guest
Thu Sep 02, 2010 10:40 pm
On Thu, 02 Sep 2010 14:38:04 -0700, Joerg <invalid_at_invalid.invalid>
wrote:
[snip]
Quote:
I once heard a
similar word of wisdom for the business side of business, and almost
spewed my coffee all over the place: Find a parade and get in front of
it
similar word of wisdom for the business side of business, and almost
spewed my coffee all over the place: Find a parade and get in front of
it
AKA: The Larkin Procedure
...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Democrats are best served up prepared as a hash
Otherwise my dogs will refuse to eat them
JosephKK
Guest
Guest
Fri Sep 03, 2010 5:45 am
On Wed, 01 Sep 2010 07:47:51 -0700, Joerg <invalid_at_invalid.invalid>
wrote:
Quote:
JosephKK wrote:
On Mon, 30 Aug 2010 08:52:09 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Fred Abse wrote:
On Sun, 29 Aug 2010 16:41:26 -0700, Joerg wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 15:21:15 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 13:51:14 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Fred Abse wrote:
On Sat, 28 Aug 2010 14:34:24 -0700, Fred Abse wrote:
Sunday's exercise might be to compare the (Philips) model's S-parameters
against Philips' data sheet values. Wanna bet they don't match?
Pretty close match, apart from S22, which doesn't show the pronounced kink
shown in the datasheet.
Shame LTSpice won't do polar plots. Since it does impedance and
S-params, it really ought to.
Found a way round that. Set LTSpice to do ASCII rawfiles, run, edit two or
three LT-specific lines out of the rawfile, and load it into Berkeley
Spice 3f4's Nutmeg, then plot polar and Smith from there.
Much easier than trying to get LTSpice netlists to run in 3f4.
I still think the facility should be in LTSpice, though.
I think Jim Thompson once mentioned a software that could render raw
data into all sorts of graphics including polar. Jim?
Scratching head... I don't remember
I believe it was a software that you could also throw scanned in plots.
Aha! I did recently buy "GetData Graph Digitizer" which can create
numerical data points from graphs in data sheets.
Handy for creating subcircuits when all you have is a data sheet.
Reverse engineering ... ?
PSpice can do about any x-y plot you'd like, but I don't know how
you'd do polar except with some innovative macros
I think LTSpice can output polar data but I have never done it. I
believe the command is "meascplxfmt polar".
Can't find any reference. .meas statements usually start with an analysis
type, like ac, tran, etc.
Polar plots uploaded to a.b.s.e. Unfortunately my hand-added annotations
of frequency end points haven't survived the upload. Added in gimp,
they're present in the .pngs here.
Can't access a.b.s.e. :-(
Falk Willberg from a German NG has set up his own news server with
binary access but that would require everyone who wants to look to have
the access info (which Falk freely gives out to anyone who requests it).
Cool. Thanks Falk.
If you want access you can request it from Falk at:
nntp at consult42 dot com
On Mon, 30 Aug 2010 08:52:09 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Fred Abse wrote:
On Sun, 29 Aug 2010 16:41:26 -0700, Joerg wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 15:21:15 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Jim Thompson wrote:
On Sun, 29 Aug 2010 13:51:14 -0700, Joerg <invalid_at_invalid.invalid
wrote:
Fred Abse wrote:
On Sat, 28 Aug 2010 14:34:24 -0700, Fred Abse wrote:
Sunday's exercise might be to compare the (Philips) model's S-parameters
against Philips' data sheet values. Wanna bet they don't match?
Pretty close match, apart from S22, which doesn't show the pronounced kink
shown in the datasheet.
Shame LTSpice won't do polar plots. Since it does impedance and
S-params, it really ought to.
Found a way round that. Set LTSpice to do ASCII rawfiles, run, edit two or
three LT-specific lines out of the rawfile, and load it into Berkeley
Spice 3f4's Nutmeg, then plot polar and Smith from there.
Much easier than trying to get LTSpice netlists to run in 3f4.
I still think the facility should be in LTSpice, though.
I think Jim Thompson once mentioned a software that could render raw
data into all sorts of graphics including polar. Jim?
Scratching head... I don't remember
I believe it was a software that you could also throw scanned in plots.
Aha! I did recently buy "GetData Graph Digitizer" which can create
numerical data points from graphs in data sheets.
Handy for creating subcircuits when all you have is a data sheet.
Reverse engineering ... ?
PSpice can do about any x-y plot you'd like, but I don't know how
you'd do polar except with some innovative macros
I think LTSpice can output polar data but I have never done it. I
believe the command is "meascplxfmt polar".
Can't find any reference. .meas statements usually start with an analysis
type, like ac, tran, etc.
Polar plots uploaded to a.b.s.e. Unfortunately my hand-added annotations
of frequency end points haven't survived the upload. Added in gimp,
they're present in the .pngs here.
Can't access a.b.s.e. :-(
Falk Willberg from a German NG has set up his own news server with
binary access but that would require everyone who wants to look to have
the access info (which Falk freely gives out to anyone who requests it).
Cool. Thanks Falk.
If you want access you can request it from Falk at:
nntp at consult42 dot com
I get a.b.s.e natively on my Astraweb account. But i gotta respect
Falk for providing the service.
JosephKK
Guest
Guest
Fri Sep 03, 2010 5:46 am
On Thu, 02 Sep 2010 10:34:42 -0700, Fred Abse
<excretatauris_at_invalid.invalid> wrote:
Quote:
On Tue, 31 Aug 2010 21:51:51 -0700, JosephKK wrote:
On Tue, 31 Aug 2010 10:17:21 -0700, Fred Abse
excretatauris_at_invalid.invalid> wrote:
On Mon, 30 Aug 2010 09:20:34 -0700, Joerg wrote:
Just a word of caution here: Don't do this for a design that has to go
into mass production. The capacitive device parameters are lot dependent
and vary with temperature.
Fortunately. there's always a bit of wiggle room, plus, my designs are
never more than a few hundred off.
I leave mass produced stuff to those with the relevant mindset (ITCFWI)
^^^^^^ Not found. Please persplain.
If The Cap Fits, Wear It
;-)
On Tue, 31 Aug 2010 10:17:21 -0700, Fred Abse
excretatauris_at_invalid.invalid> wrote:
On Mon, 30 Aug 2010 09:20:34 -0700, Joerg wrote:
Just a word of caution here: Don't do this for a design that has to go
into mass production. The capacitive device parameters are lot dependent
and vary with temperature.
Fortunately. there's always a bit of wiggle room, plus, my designs are
never more than a few hundred off.
I leave mass produced stuff to those with the relevant mindset (ITCFWI)
^^^^^^ Not found. Please persplain.
If The Cap Fits, Wear It
;-)
Thranx
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