020170
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simulation ac dc cmrr
I read following link.
V1 and V2 has no DC value and V1 and V2 has AC 1
In hspice syntax, this can be written like this (Fig 1.)
V1 INP GND DC 0 AC 1
V2 INN OUT DC 0 AC 1
I don't understand why this topology was used to simulation CMRR.
Instead of this simulation way, I was used this method to simulate CMRR
1. First, get Differential Gain
X_OPAMP INP INN OUT VDD GND
V1 INP VCM DC 0 AC 1
V2 INN VCM DC 0
VCM VCM GND DC 1
2. Second, get Common Gain
X_OPAMP INP INN OUT VDD GND
V1 INP VCM DC 0
V2 INN VCM DC 0
VCM VCM GND DC 1 AC 1
In the end, 1 - |2| = CMRR
Is this method correct?
thanks.
I read following link.
V1 and V2 has no DC value and V1 and V2 has AC 1
In hspice syntax, this can be written like this (Fig 1.)
V1 INP GND DC 0 AC 1
V2 INN OUT DC 0 AC 1
I don't understand why this topology was used to simulation CMRR.
Instead of this simulation way, I was used this method to simulate CMRR
1. First, get Differential Gain
X_OPAMP INP INN OUT VDD GND
V1 INP VCM DC 0 AC 1
V2 INN VCM DC 0
VCM VCM GND DC 1
2. Second, get Common Gain
X_OPAMP INP INN OUT VDD GND
V1 INP VCM DC 0
V2 INN VCM DC 0
VCM VCM GND DC 1 AC 1
In the end, 1 - |2| = CMRR
Is this method correct?
thanks.