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https://designers-guide.org/forum/YaBB.pl Simulators >> RF Simulators >> simulation of VCO pulling caused spur https://designers-guide.org/forum/YaBB.pl?num=1204880225 Message started by chenyan on Mar 7th, 2008, 12:57am |
Title: simulation of VCO pulling caused spur Post by chenyan on Mar 7th, 2008, 12:57am How can we simulate VCO pulling caused spurs? Running PSS with spectrRF seems not working. Is there a way or a tool to simulate this? Running transient and then make laplace transform? cheers chen |
Title: Re: simulation of VCO pulling caused spur Post by pancho_hideboo on Mar 10th, 2008, 8:58am Quote:
Do you mean injection pulling where VCO is pulled by large RX interference for example ? If so, you can simulate by multitone HB analysis where one autonomous signal and at least one drive signal are involved. This simulation is possible with Agilent ADS(RFDE) and GoldenGate. Previously Cadence SpectreRF QPSS couldn't deal with mixture of autonomous and drive signals. I don't know whether SpectreRF QPSS come to be able to deal with this. |
Title: Re: simulation of VCO pulling caused spur Post by chenyan on Mar 12th, 2008, 7:08am Thanks Pancho! I tried with ADS HB simulation, but if you add a small injection current at 400KHz to the VCO running at 4GHz. HB simulation ingored the injected current as its frequency is not close enough to VCO harmonics. Then I set freq1 in the HB to be 400KHz, I need to set the HB order very high and it really can not converge. Could you please let me know how you did this simulation in ADS. Thanks a lot. |
Title: Re: simulation of VCO pulling caused spur Post by pancho_hideboo on Mar 13th, 2008, 12:56am Quote:
Do you activate OscMode in HB analysis ? Show me netlist about analysis setting and signal source setting. BTW, it seems that Cadence HB-QPSS(MMSIM 6.2) doesn't support autonomous QPSS yet. |
Title: Re: simulation of VCO pulling caused spur Post by chenyan on Mar 14th, 2008, 2:14am Hi, here is the netlist. A simple NMOS cross coupled VCO at 2GHz, with a 400kHz injection current. Thanks. Options ResourceUsage=yes UseNutmegFormat=no TopDesignName="D:\users\default\spur_prj\networks\hb" I_Source:SRC2 0 _net179 Type="ItSine" I[1]=if (_tr_state == 0) then 100 uA*exp(j*2*pi*(0/360-0 nsec*400 kHz-.25)-(time-0 nsec)*0)*step((time-0 nsec)+tinyreal) else 0 endif Freq[1]=400 kHz Idc=0 mA I_Tran=if (_tr_state == 1) then damped_sin(time,0,100 uA,400 kHz,max(0,0 nsec),0,0) else 100 uA*step((0 nsec-time)-tinyreal)*sin(pi*0/180) endif Noisecon:NC1 InputFreq=noisefreq NoiseFreqPlan="NC1_nl_stim" \ NoiseInputPort=1 NoiseOutputPort=2 PhaseNoise=1 NoiseNode[1]="Vout1 Vout2" SortNoise=1 \ IncludePortNoise=yes \ BandwidthForNoise=1.0 Hz SweepPlan: NC1_nl_stim Start=1.0 kHz Stop=100 MHz Dec=5 HB:HB1 MaxOrder=4 Freq[1]=2 GHz Order[1]=10 StatusLevel=2 FundOversample=5 \ UseAllSS_Freqs=yes OutputBudgetIV=no OscPortName="Yes" \ NoiseFreqPlan="HB1_nl_stim" InputFreq=noisefreq NoiseInputPort=1 NoiseOutputPort=2 PhaseNoise=yes NoiseNode[1]="Vout1" NoiseNode[2]="Vout2" SortNoise=1 BandwidthForNoise=1.0 Hz \ OutputPlan="HB1_Output" Noisecon[1]="NC1" SweepPlan: HB1_nl_stim Start=1 kHz Stop=100 MHz Dec=1 OutputPlan:HB1_Output \ Type="Output" \ UseNodeNestLevel=yes \ NodeNestLevel=2 \ UseEquationNestLevel=yes \ EquationNestLevel=2 \ UseSavedEquationNestLevel=yes \ SavedEquationNestLevel=2 \ UseDeviceCurrentNestLevel=no Tran:HB1_tran HB_Sol=1 SteadyState=1 StatusLevel=3 \ Freq[1]=2 GHz Order[1]=10 \ OutputPlan="HB1_Output" Component:tahb_HB1 Module="ATAHB" Type="ModelExtractor" \ Tran_Analysis="HB1_tran" HB_Analysis="HB1" "BSIM4M1":MOSFET2 Vout1 Vout2 0 0 Length=0.13 um Width=50 um Mode=1 Noise=yes #uselib "ckt", "OscPort2" OscPort2:OscP1 _net129 _net130 Vout2 Vout1 Z=1.1 Ohm NumOctaves=2 Steps=10 FundIndex=1 Harm=1 "BSIM4M1":MOSFET1 Vout2 Vout1 0 0 Length=0.13 um Width=50 um Mode=1 Noise=yes model BSIM4M1 BSIM4 NMOS=1 PMOS=0 V_Source:SRC1 _net179 0 Type="V_DC" Vdc=2 V SaveCurrent=1 C:C2 _net130 _net129 C=2 pF C:C1 _net130 _net129 C=1.0 pF L:L2 _net179 _net129 L=1.0 nH R=1 Ohm Noise=yes L:L1 _net130 _net179 L=1.0 nH R=1 Ohm Noise=yes |
Title: Re: simulation of VCO pulling caused spur Post by pancho_hideboo on Mar 14th, 2008, 3:50am Quote:
Why do you use ItSine as SRC2 ? Basically this is a time domain signal source although it seems to be valid even for HB as I see the above I_Source description. What effect do you expect in your simulation ? Do you expect transient assisted HB, where HB convergence is helped by time domain SRC2 drive ? Do you understand HB analysis, HB with small Signal Analysis, pure small signal analysis, envelope analysis, etc. ? Quote:
The reason is you do only 1 tone HB ana while 2 large signals exist. Quote:
You have to use 2 tone HB ana. 400kHz must be set as Freq[2]. Freq[1] is autonomous large signal. There are three possibilities for simulations of VCO purturbed by some signal, although (1) is actually not purturbation, that is, not pulling. (1) 1 tone HB base Noise Analysis, One autonoumous signal(2GHz) + small signal noise source having specific PSD. In this case, you have to use I_Noise as SRC2. (2) 2 tone HB base Noise Analysis, One autonoumous signal(2GHz) + One fixed signal(400kHz) In this case, you have to use I_1tone as SRC2. (3) 2 tone Envelope base Noise Analysis, One autonoumous signal(2GHz) + One fixed signal(400kHz) In this case, you can use any complex envelope signal centered at 400kHz as SRC2. About (1), you can also do by using PSS(Shooting or HB) of SpectreRF. I confirmed Cadence HB-QPSS(MMSIM 6.2) doesn't support autonomous QPSS yet. So Cadence MMSIM 6.2 can't do (2). About (3), I don't know whether SpectreRF(MMSIM6.2) can do. Except for (3), you can do with only using Cadence analoglib in Agilent RFDE. About (3), there are some limits if you don't use adsLib in Agilent RFDE. What simulation you should use is depend on what effect you want to evaluate. I guess you want to do (2). |
Title: Re: simulation of VCO pulling caused spur Post by pancho_hideboo on Mar 17th, 2008, 5:10am About (1), see http://www.designers-guide.org/Forum/YaBB.pl?num=1151438219 |
Title: Re: simulation of VCO pulling caused spur Post by chenyan on Mar 19th, 2008, 7:13am Thank you so much. I have now solved the problem sccording to your information. |
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