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1、折叠式级联运放的仿真The Typical Performance of Op-AmpThe Typical Performance of Op-Ampn nOpen-Loop Differential Gain(AOpen-Loop Differential Gain(AV V)n nCommon-mode Rejection Ratio(CMRR)Common-mode Rejection Ratio(CMRR)n nPower Signal Rejection Ratio(PSRR)Power Signal Rejection Ratio(PSRR)n nPhase Margin(PM)
2、Phase Margin(PM)n nInput Common Mode RangeInput Common Mode Range(ICMR)(ICMR)n nOutput Swing RangeOutput Swing Range(OSR)(OSR)n nInput/Output Impedance(CInput/Output Impedance(CININ/R/ROUTOUT)n nSlew RateSlew Raten nNoiseNoiseThe Schematic of Folded Cascode Op-AmpThe Schematic of Folded Cascode Op-A
3、mpIn order to decease the power Consumption,IBIAS is only 30nA.Create Schematic and Symbol in SpectreCreate Schematic and Symbol in SpectreTo create a symbol of a schematic:From Design-Create Cellview-From CellviewOpen-Loop Differential Gain Open-Loop Differential Gain n nDC Sweep VP-VN (large signa
4、l)n nAC Sweep VP-VN with fixed frequency(small signal)Two methods of simulating Open-Loop Differential Gainis available in ADE(Analog Design Environment)Test-Bench of Open-Loop Differential Gain Test-Bench of Open-Loop Differential Gain(method 1)(method 1)DC Sweep DC Sweep V VP P-V VN N (large signa
5、l)(large signal)In this method,VP=VCM_IN+x,and VN=VCM_IN-xWhere,VCM_IN is the common voltage,x is a design variables.Setup VNSetup VPADE of Open-Loop Differential Gain ADE of Open-Loop Differential Gain(method 1)(method 1)To add a model for the simulation From ADE-Setup-Model librariesTo create a DC
6、 SweepFrom ADE-Analyses-Choose-DCWaveform of Open-Loop Differential Gain Waveform of Open-Loop Differential Gain(method(method 1)1)Where,Differential Gain is 71.56dBTo obtain VCOM_OUT From Calculator-Special Functions-ValueVOUT-VCOM_OUTTo obtain DC gain From Calculator-Special Functions-derivTest-Be
7、nch of Open-Loop Differential Gain Test-Bench of Open-Loop Differential Gain(method 2)(method 2)AC Sweep AC Sweep V VP P-V VN N with fixed frequency with fixed frequencySetup VNSetup VPIn this method,VP=VCM_IN+x+VAC,and VN=VCM_INWhere,VCM_IN is the input common voltage,x is a design variables,VAC is
8、 a AC voltage for AC Sweep.ADE of Open-Loop Differential Gain ADE of Open-Loop Differential Gain(method 2)(method 2)To add a model for the simulation From ADE-Setup-Model librariesTo create a AC SweepFrom ADE-Analyses-Choose-ACFixedFreqWaveform of Open-Loop Differential Gain Waveform of Open-Loop Di
9、fferential Gain(method(method 2)2)Differential Gain is 65.56dB The results of the two methods are different,In fact,method 1 is more accurate for DC gain.Common-mode Rejection RatioCommon-mode Rejection Ratio You can get detail illustration from“CMOS Analog Circuit Design”,Phillip E.Allen,Oxford Uni
10、versity Press,Inc.Test-Bench of CMRRTest-Bench of CMRRWhere,VCOM_IN is the input common voltage,VAC is a AC voltage for AC Sweep.ADE of CMRRADE of CMRRTo add a model for the simulation From ADE-Setup-Model librariesTo create a AC SweepFrom ADE-Analyses-Choose-ACWaveform of CMRRWaveform of CMRR1/CMRR
11、CMRRTo obtain CMRR:From Calculator-1/x1/CMRR and CMRR plot directly.Waveform of CMRRWaveform of CMRRTo obtain magnitude Plot of CMRR:From Calculator-dB20Frequency response of CMRRThe CMRR is 72.14dB at low frequency range.To obtain phase Plot of CMRR:From Calculator-phasePower Signal Rejection Ratio
12、Power Signal Rejection Ratio You can get detail illustration from“CMOS Analog Circuit Design”,Phillip E.Allen,Oxford University Press,Inc.Test-Bench of PSRRTest-Bench of PSRRWhere,VAC is a AC voltage for AC Sweep,and VDC is a DC voltage ADE of PSRRADE of PSRRTo add a model for the simulation From AD
13、E-Setup-Model librariesTo create a AC SweepFrom ADE-Analyses-Choose-ACWaveform of PSRRWaveform of PSRR1/PSRRPSRRTo obtain CMRR:From Calculator-1/x1/PSRR and PSRR plot directly.Waveform of PSRRWaveform of PSRRTo obtain magnitude Plot of PSRR:From Calculator-dB20Frequency response of PSRRThe CMRR is 7
14、9.17dB at low frequency range.To obtain phase Plot of PSRR:From Calculator-phasePhase Margin of Open-loop frequency ResponsePhase Margin of Open-loop frequency Response Where,VCM_IN is the input common voltage,VAC is a AC voltage for AC Sweep,And CL is the loading capacitor.Test-Bench of PMTest-Benc
15、h of PMVCM_INVACThe dominant pole is controlled by CL in folded Cascode op amp.ADE of PMADE of PMTo add a model for the simulation From ADE-Setup-Model librariesTo create a AC SweepFrom ADE-Analyses-Choose-ACWaveform of PMWaveform of PMTo obtain magnitude Plot of open-loop:From Calculator-dB20open-l
16、oop frequency responseThe PM is 74o when CL is 5pf.To obtain phase Plot of open-loop:From Calculator-phase There have two poles in open-loop frequencyresponse,one is the dominant pole of output net,and the another is the mirror pole caused by active current mirror.Input Common-mode RangeInput Common
17、-mode RangeWhere,x is a design variables and CL is the loading capacitor.Test-Bench of ICMRTest-Bench of ICMRADE of ICMRADE of ICMRTo add a model for the simulation From ADE-Setup-Model librariesTo create a DC SweepFrom ADE-Analyses-Choose-DCWaveform of ICMRWaveform of ICMRICMRThe input common-mode
18、range is 04.2VOutput Swing RangeOutput Swing RangeWhere,VCM_IN is the input common voltage,x is a design variables.To obtain OSRTest-Bench of OSR Test-Bench of OSR DC Sweep DC Sweep V VP P-V VN N In this method,VP=VCM_IN+x,and VN=VCM_IN-xWhere,VCM_IN is the common voltage,x is a design variables.Set
19、up VNSetup VPADE of OSR ADE of OSR To add a model for the simulation From ADE-Setup-Model librariesTo create a DC SweepFrom ADE-Analyses-Choose-DCWaveform of OSR Waveform of OSR You can get the left waveform from page 8.OSRThe output swing range is from 842.5mV to 4.381V.PS:OSR is dependence of appl
20、ications and is not constant.Input CapacitorInput CapacitorWhere,VCM_IN is the input common voltage,VAC is AC voltage for AC Sweep.Test-Bench of CTest-Bench of CININVCM_INVACADE of CADE of CININTo add a model for the simulation From ADE-Setup-Model librariesTo create a AC SweepFrom ADE-Analyses-Choo
21、se-ACWaveform of CWaveform of CININ The input capacitor is approximate of 5pfOutput ResistanceOutput Resistance The schematic of obtaining open-loop output resistance RO.The equivalent model by using Thevenin form On the op amp.Thus,simulating ROUT and knowing AV allows one to calculate the output r
22、esistance RO of the op amp.Test-Bench of RTest-Bench of ROUTOUTIOUTVOUT200RR=1GVIN=0VADE of RADE of ROUTOUTTo add a model for the simulation From ADE-Setup-Model librariesTo create a TRAN SweepFrom ADE-Analyses-Choose-TRANWaveform of RWaveform of ROUTOUT IOUTROUTSlew RateSlew Rate The unity-gain con
23、figuration places the severest requirements on stabilityand slew rate because its feedback is the largest,resulting in the largest values of loop-gain,and should always be used as a worst-case measurement.Test-bench of Slew RateTest-bench of Slew RateThe input step magnitude is 2V.ADE of SR ADE of S
24、R To add a model for the simulation From ADE-Setup-Model librariesTo create a TranFrom ADE-Analyses-Choose-TranWaveform of SRWaveform of SR SR=95.1K V/sNoise Noise n n Thermal Noise Thermal Noise (A)channel noise(id)(A)channel noise(id)(A)R (A)RS S noise(rs)noise(rs)(A)R (A)RD D noise(rd)noise(rd)n
25、n Flicker Noise(fn)Flicker Noise(fn)Test-Bench of NoiseTest-Bench of NoiseVCM_INVACThe dominant pole is controlled by CL in folded Cascode op amp.ADE of NoiseADE of NoiseTo add a model for the simulation From ADE-Setup-Model librariesTo create a NoiseFrom ADE-Analyses-Choose-noiseWaveform of NoiseWaveform of NoiseOutput noiseInput-referred noiseTo obtain output noise and input-referred noise:From ADE-results-Direct plot-main form