Analog circuit design flow

[yassin2705]

circuit design flow

Hi friends,

I am starting to design a folded-cascode fully differential amplifier OTA with CMFB. I am confused and don't know how to start because of the large number of mosfets. I know that the ideal flow is to start with hand analysis then move to the simulation stage, but I have two problems with hand-analysis, first is the large number of assumptions that i should made because of the large number of parameters. Secondly, the hand analysis results are not accurate anyway, so does it deserve all that effort!!

Also, I think in the simulation stage, we should divide the circuit into many subcircuits taking into consideration the loading between these subcircuits, is taht correct??

Also, how to select the optimum mos device from the available mos devices in the design kit??

I want an advice from analog desin experts to know the optimum flow.

Thanks!
yassin

 

[wpchan05]

analog circuit design flow

Hi friends,

I am starting to design a folded-cascode fully differential amplifier OTA with CMFB. I am confused and don't know how to start because of the large number of mosfets. I know that the ideal flow is to start with hand analysis then move to the simulation stage, but I have two problems with hand-analysis, first is the large number of assumptions that i should made because of the large number of parameters. Secondly, the hand analysis results are not accurate anyway, so does it deserve all that effort!!

Also, I think in the simulation stage, we should divide the circuit into many subcircuits taking into consideration the loading between these subcircuits, is taht correct??

Also, how to select the optimum mos device from the available mos devices in the design kit??

I want an advice from analog desin experts to know the optimum flow.

Thanks!
yassin

I would use unit size mosfet to simulate the opamp, and used the hand calculation formula to adjust the mosfet's aspect ratio to suit my requirements.

 

[yassin2705]

Is it useful to make initial simulation using level 1 models which uses mos simple equations just as a start with the hand analysis, then we can move to the simulation with its results as ana initial vaue?

Or this will be just time wasting??

 

[tdy]

It's about how good you want to do it.

 

[yusen1023]

I would use unit size mosfet to simulate the opamp, and used the hand calculation formula to adjust the mosfet's aspect ratio to suit my requirements.

What do you mean about the "unit size mosfet"? Do you use the same mosfet in the simulation?

 

[wpchan05]

I would use unit size mosfet to simulate the opamp, and used the hand calculation formula to adjust the mosfet's aspect ratio to suit my requirements.

What do you mean about the "unit size mosfet"? Do you use the same mosfet in the simulation?

unit size with different m-factor....