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https://designers-guide.org/forum/YaBB.pl Design >> RF Design >> What value for Order and MaxOrder in HB simulation https://designers-guide.org/forum/YaBB.pl?num=1191464825 Message started by asb1211 on Oct 3rd, 2007, 7:27pm |
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Title: What value for Order and MaxOrder in HB simulation Post by asb1211 on Oct 3rd, 2007, 7:27pm In ADS2004A => DesignGuide => Mixer => Single-end mixer characterization => 2nd- and 3rd-order IMD and conv. gain example, HB simulation controller is set up as following: MaxOrder=6 Freq[1]=LOfreq Freq[2]=RFfreq + Fspacing/2 Freq[2]=RFfreq - Fspacing/2 Order[1]=9 Order[2]=3 Order[3]=3 OrderSample[1]=1 OrderSample[2]=1 OrderSample[3]=1 UseKrylov=yes and in variable decralation there are: VAR LOfreq = 900 MHz RFfreq = 1100 MHz Fspacing = 200 kHz P_RF = -30 dBm P_LO = 0 dBm Now, I want to use the simulation setup for my Mixer design, pHEMT resistive passive mixer where: LOfreq = 2350 MHz RFfreq = 2400 MHz P_RF = 0 dBm P_LO = 15 dBm Fspacing = 1 MHz Anyone could tell me what value should I set or how I can decide the value of MaxOrder and Order for LO and input RF tones when I want to simulate the IIP3 of the designed mixer? Also, I read somewhere that MaxOrder ≥|k1| + |k2| + ... + |kn| where kn is the harmonic for the nth tone in the circuit. Can k1 be not integer? or why in the inequality, there need to use the absolute of kn? |
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Title: Re: What value for Order and MaxOrder in HB simula Post by pancho_hideboo on Oct 5th, 2007, 10:28am Hi. It seems that nobody answers your question in both this board and EDAboard. http://www.edaboard.com/ftopic274169.html Do you surely read ADS's manual or http://eesof.tm.agilent.com/docs/adsdoc2004A/pdf/adshbapp.pdf ? Why don't you simply begin with same setting as DesignGuide(Order[1]=9, Order[2]=3, Order[2]=3, MaxOrder=6) ? Then see differences of results by increasing MaxOrder and Order[n]. This is common procedure in multitone HB analysis. [Note] IM3 terms are LO-(2*RF1-RF2) or LO-(2*RF2-RF1). These are expressed with MaxOrder=4. Since you are designing resistive mixer, LO power is very large, so more order and more oversample might be needed. Why do you set large power(0dBm) as RF although you are evaluating IIP3 ? If you set two RF input power as 0dBm, their combined peak envelope power could be 6dBm which is lesser than LO Power(15dBm) only by 9dB. I can't expect linear input condition for RF. Although I don't know your thought and circuit's topology, I set RF power lesser than -6dBm. Anyway you have to sweep RF input power. I begin with two tone(LO and RF1 are large, RF2 is small) HB analysis using ADS's HB Small Signal Analysis which is same as PSS/PAC of SpectreRF. Then I proceed to three tone(LO, RF1 and RF2 are large) HB analysis. |
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Title: Re: What value for Order and MaxOrder in HB simula Post by asb1211 on Oct 10th, 2007, 10:39pm Hi pancho_hideboo, Many thanks and appreciation for your guide and comment. Quote:
Yes, I did follow the DesignGuide and gradually increased MaxOrder. The point is simulation results seem not argree each other. As my thought, increasing Order results more accuracy with the trade-off of simulation time. More over, increasing order is supposed to decrease calculated linearity. However, simulation results disagree with the "calculated linearity" statement. Could you plz explain about that for me? Quote:
DesignGuide comments that "P_RF. This should be at least 15 dB below the 1 dB compression power level" My designing introduces P1dB 15-18 dBm. So P_RF could be 0 dB or less. Another reason is, when I looked through AnalogDevide ADL5350 datasheet (page 3 of 24), they also measure IIP3 @ each RF tone 0 dBm. So, I set P_RF = 0 dBm as a comparison. One more question: Whole design includes a mixer core and a LO buffer amplifier (with DC couple caps at input and output). When I simulated without the buffer, there is no problem but when I added buffer, then it was very difficult to converge (not a single time the simulation was succeeded. I didn't have the same problem if I followed simulation setup in Examples/RFIC/Mixers_prj/MixerTOI.dsn . I have no idea why it was. BTW, could you comment on the differences between DesignGuide setup and Examples setup? |
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Title: Re: What value for Order and MaxOrder in HB simula Post by pancho_hideboo on Oct 11th, 2007, 2:40am Hi. :-? Order[1]=9 ; LO Order[2]=3 ; RF1 Order[3]=3 ; RF2 MaxOrder=6 are reasonable as initial setting, I think. In this case, largest MutualOrder could be 15. But 15 is too large. In general, IM3 and IM5 are important, so MaxOrder of 6 is reasonable since IM5 is expressed as Mutual Order of 6. If you would like to input large RF power like 0dBm, you might be needed to increase Order[2] and Order[3]. Anyway you should sweep RF power. > Yes, I did follow the DesignGuide and gradually increased MaxOrder. > The point is simulation results seem not argree each other. What do you see as results ? Your frequencies are following. LO = 2350 MHz RF1 = 2400 MHz-0.5MHz RF2 = 2400 MHz+0.5MHz You should plot output powers of RF1-LO, RF2-LO, (2*RF1-RF2)-LO and (2*RF2-RF1)-LO with RFpower sweep. If you see appropriate outputs I expect, your circuits is too nonlinear that it can't converge to true results with initial setting. Could you upload simulation results curve ? > As my thought, increasing Order results more accuracy with the trade-off of simulation time. correct. > More over, increasing order is supposed to decrease calculated linearity. > However, simulation results disagree with the "calculated linearity" statement. What do you mean by "calculated linearity" ? > One more question: Whole design includes a mixer core and a LO buffer amplifier (with DC couple caps at input and output). > When I simulated without the buffer, there is no problem but when I added buffer, > then it was very difficult to converge (not a single time the simulation was succeeded. > I didn't have the same problem if I followed simulation setup in Examples/RFIC/Mixers_prj/MixerTOI.dsn . > I have no idea why it was. BTW, could you comment on the differences between DesignGuide setup and Examples setup? I checked "Examples/RFIC/Mixers_prj/MixerTOI.dsn". Order[1]=5 ; LO Order[2]=3 ; RF1 Order[3]=3 ; RF2 MaxOrder=4 This is minimum setting for IM3 evaluation. Usually this results could be inaccurate. The followings are part of netlist for HB(TAHB) control for \examples\RFIC\Mixers_prj\networks\MixerTOI. I don't have license of DesignGuide, so show me the netlist of DesignGuide. ============================================================================================ HB:HB2 MaxOrder=4 Freq[1]=LOfreq Freq[2]=RFfreq+fspacing/2 Freq[3]=RFfreq-fspacing/2 Order[1]=5 Order[2]=3 Order[3]=3 StatusLevel=2 FundOversample=1 \ Restart=no UseAllSS_Freqs=yes UseOutFile=no UseInFile=no OutputPlan="HB2_Output" ConvMode=2 MaxIters=10 ArcLevelMaxStep=0.0 MaxStepRatio=100 MaxShrinkage=1.0e-5 ArcMaxStep=0.0 \ UseKrylov=yes SamanskiiConstant=2 \ Tran:HB2_tran HB_Sol=1 SteadyState=1 StatusLevel=3 \ Freq[1]=LOfreq Order[1]=5 \ OutputPlan="HB2_Output" Component:tahb_HB2 Module="ATAHB" Type="ModelExtractor" \ Tran_Analysis="HB2_tran" HB_Analysis="HB2" |
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