The Designer's Guide Community Forum - Class B RF Power Amplifier ,IIP3/OIP3 Spectre

pancho_hideboo

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Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre
Reply #30 - Jun 29^th, 2010, 6:51am

You set f1=2490MHz as small signal in PAC analysis.

Show me followings.

(1) Over Plot Results of fundamental output(f1=2490MHz, f2=2495MHz) for QPSS and PSS/PAC.

(2) Over Plot Results of IM3 output for QPSS(2485MHz and 2500MHz) and PSS/PAC(2500MHz).

If you can not do them, upload "simulation/"test_bench_name"/spectre/schematic" for QPSS and PSS/PAC.

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purplewolf Community Member Offline Posts: 56	Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre Reply #31 - Jun 29^th, 2010, 7:21am theres a slight difference in the third order , the fundamental are the same
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pancho_hideboo Senior Fellow Offline Posts: 1362 Real Homeless	Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre Reply #32 - Jun 29^th, 2010, 7:37am Show me version of Cadence Spectre you use. Also show me time waveform for Idrain, Vdrain, Iload and Vload. These can be available in PSS results for PSS/PAC.
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purplewolf Community Member Offline Posts: 56	Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre Reply #33 - Jun 29^th, 2010, 10:10am Here are the waveforms for drain current ,drian voltage, output current and output voltage
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purplewolf Community Member Offline Posts: 56	Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre Reply #34 - Jun 29^th, 2010, 10:10am .
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purplewolf Community Member Offline Posts: 56	Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre Reply #35 - Jun 29^th, 2010, 10:12am The version is 7.0.1.273
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pancho_hideboo

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Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre
Reply #36 - Jun 29^th, 2010, 10:34am

purplewolf wrote on Jun 29^th, 2010, 10:10am:

Here are the waveforms for drain current ,drian voltage, output current and output voltage

You can't understand my requests.

My request is time waveform with Pin_dBm as parameters.
See my simulation results surely.

I don't think your amplifier is Class-B operation, although I don't know what Pin_dBm value is used for time waveform you showed.

purplewolf wrote on Jun 29^th, 2010, 10:12am:

The version is 7.0.1.273

Use more new Cadence Spectre.

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purplewolf Community Member Offline Posts: 56	Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre Reply #37 - Jun 30^th, 2010, 3:02am here are the Pin_dbm sweep results from -30 to 30..
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RFICDUDE

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Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre
Reply #38 - Jun 30^th, 2010, 3:18am

When I look at your earlier two-tone sweep data, it looks like there is
1. a little bit of gain expansion before compression (although it is difficult to tell from just looking at the plot)
2. the IM3 has definite dips (nulls if you like) near where the gain expansion is occurring

IF you do have some gain expansion before compression then this will definite violate the condition necessary for 9.6 dB P1dB to OIP3 relationship. The gain expansion can make P1dB happen at an input power level that is higher than that of a classic class A amplifier.

I will look at the latest plots later, but it seems your circuit is operating class AB.

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purplewolf Community Member Offline Posts: 56	Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre Reply #39 - Jun 30^th, 2010, 3:47am yes exactly..the nulls make my class B violate the expressions.. well , its almost class B.
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pancho_hideboo

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Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre
Reply #40 - Jun 30^th, 2010, 4:28am

purplewolf wrote on Jun 30^th, 2010, 3:47am:

yes exactly..the nulls make my class B violate the expressions..
well , its almost class B.

Why is drain current of the following not coincident to any of Transient Analysis ?
http://www.designers-guide.org/Forum/Attachments/IVD.png
This drain current is not for Class-B operation completely.

On the other hand, drain currents in your Transient Analysis are for Class-B operation.

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purplewolf

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Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre
Reply #41 - Jun 30^th, 2010, 5:05am

i get this problem of ''....not a kept output'' when plotting current through pss....so , i prefer transient in plotting currents because i am unable to fix that problem with pss other than using some 'tricks'.
the transient current waveform is accurate...
you can ignore IVD.png or help me figure out this problem with pss??

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pancho_hideboo

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Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre
Reply #42 - Jun 30^th, 2010, 5:10am

purplewolf wrote on Jun 30^th, 2010, 5:05am:

i get this problem of ''....not a kept output'' when plotting current through pss....

I think you can get same time domain waveform current as Transient Analysis, even if you use HB-PSS of Cadence Spectre.

purplewolf wrote on Jun 30^th, 2010, 5:05am:

you can ignore IVD.png or help me figure out this problem with pss??

Are your results of PSS/PAC and QPSS using Cadence Spectre truely correct ?

Try to use Shooting-Newton-PSS not HB-PSS.

Do you have other vendor's simulator such as Agilent RFDE(ADSsim), Agilent GoldenGate, Synopsys HSPICE-RF, Mentor eldoRF ?

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purplewolf Community Member Offline Posts: 56	Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre Reply #43 - Jun 30^th, 2010, 6:03am yes , my qpss,pss-pac simulation are correct.. i am trying to figure out how to deal with t '...not a kept output ' problem i get in current......tahts why for the IV waveforms i use transient rather than pss.. yes , i only have golden gate but i havent used it once...im only relying on spectre.
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pancho_hideboo

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Re: Class B RF Power Amplifier ,IIP3/OIP3 Spectre
Reply #44 - Jun 30^th, 2010, 6:10am

purplewolf wrote on Jun 30^th, 2010, 6:03am:

...not a kept output ' problem i get in current......tahts why for the IV waveforms i use transient rather than pss..

I can't understand what is your problem in PSS, if your PSS result is correct.

purplewolf wrote on Jun 30^th, 2010, 6:03am:

yes , i only have golden gate but i havent used it once...

Agilent GoldenGate is difficult to use correctly.
See http://www.designers-guide.org/Forum/YaBB.pl?num=1268404959/7#7

purplewolf wrote on Jun 30^th, 2010, 6:03am:

im only relying on spectre.

I can have access to almost all vendor's simulator, but I don't use Cadence Spectre for RF circuit design.

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