运放基本仿真步骤解析

Setup VN
Setup VP
In this method, VP=VCM_IN+ x +VAC, and VN=VCM_IN Where, VCM_IN is the input common voltage, x is a design variables, VAC is a AC voltage for AC Sweep.
To create a symbol of a schematic: From Design->Create Cellview->From Cellview
Open-Loop Differential Gain
Two methods of simulating Open-Loop Differential Gain is available in ADE (Analog Design Environment)
VN
VOUT
VP VN VOUT
10/5 M=1
10/5 M=1
VBIAS=1.2V
In order to decease the power Consumption, IBIAS is only 30nA.
12/12 M=1
12/12 M=1
48/12 M=4
48/12 M=4
GND
Create Schematic and Symbol in Spectre
Setup VN In this method, VP=VCM_IN +x, and VN=VCM_IN-x Where, VCM_IN is the common voltage, x is a design variables.
Setup VP
ADE of Open-Loop Differential Gain (method 1)
ADE of Open-Loop Differential Gain (method 2)
To add a model for the simulation From ADE->Setup->Model libraries
Fixed Freq
To create a AC Sweep From ADE->Analyses->Choose->AC
To obtain VCOM_OUT From Calculator-> Special Functions->Value
VOUT -VCOM_OUT
AV
VOUT VCOM _ OUT VP VN

VOUT VCOM _ OUT 2x
Where,
VCOM _ OUT VOUT |x0
Differential Gain is 65.56dB
Common-mode Rejection Ratio
Vcm VP VN Vcm VOUT
A VOUT AC 1 C Vcm 1 AV AC AV CMRR
AC AV CMRR
You can get detail illustration from “CMOS Analog Circuit Design”, Phillip E. Allen, Oxford University Press, Inc.


DC Sweep VP -VN (large signal) AC Sweep VP -VN with fixed frequency (small signal)
Test-Bench of Open-Loop Differential Gain (method 1)
DC Sweep VP -VN (large signal)
Waveform of OpenБайду номын сангаасLoop Differential Gain (method 2)
AV 20log10 VOUT
The results of the two methods are different, In fact, method 1 is more accurate for DC gain.
折叠式级联运放的仿真
The Typical Performance of Op-Amp



Open-Loop Differential Gain (AV) Common-mode Rejection Ratio (CMRR) Power Signal Rejection Ratio (PSRR) Phase Margin (PM) Input Common Mode Range (ICMR) Output Swing Range (OSR) Input/Output Impedance (CIN/ROUT) Slew Rate Noise
Test-Bench of CMRR
Where,
VN VP Vcm VCOM _ IN VAC
VCOM_IN is the input common voltage, VAC is a AC voltage for AC Sweep.
The Schematic of Folded Cascode Op-Amp
BIAS VDD
24/12 M=1 48/12 M=6 6/12 M=1 6/12 M=1
Folded Cascode
IBIAS=30nA
VP
VDD=5V 10/5 M=1 10/5 M=1
48/12 M=2
48/12 M=2
To add a model for the simulation From ADE->Setup->Model libraries
To create a DC Sweep From ADE->Analyses->Choose->DC
Waveform of Open-Loop Differential Gain (method 1)
To obtain DC gain From Calculator-> Special Functions->deriv
Differential Gain is 71.56dB
Test-Bench of Open-Loop Differential Gain (method 2)
AC Sweep VP -VN with fixed frequency