Question on Differential Folded Cascode OTA Simulation

[Pack]

Qn on OTA Simulation

Hi,
I had designed a Fully DIfferential Folded Cascode OTA. Now I want to characterize this OTA for CMRR,PSRR,SFDR,IMD,Slew Rate etc. The measurement setup for some of the above parameters need OTA to be configured in Unity Feedback. Now the question is

1. Can I have equal valued RESISTORS in input and feedback side of OTA which has 1pF load at both outputs?

2. If reistors are not allowed for OTA and should capacitive feedback alone be used to construct unity feedback for OTA, Please tell me the way of setting the DC bias for this.

3. For CMRR and PSRR measurements, is it needed to introduce mismatch in differential pair?

4. Can anyone tell me the way to simulate SFDR for an OTA.

Thanks Forum,
Pack

 

[noiseless]

Re: Qn on OTA Simulation

If you use resistor make a unit feedback, just be aware the open loop gain will be affected by the resistor if its value is not large enough

use capacitance, be aware it will affect bandwidth and phase for it adds load to the output

for the smrr and psrr, do not introduce the mismatch to the differential pair. check their definition