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Help me with errors in switch cap integrator

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newtoanalogdesign

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switch cap integrator

i have designed a differential switched capacitor integrator. but the problem is at the output i am not getting the full step what i required.
The ota i have used is the telescopic ota having a gain of 63db, ugb of 1.3GHz and
2 volts pek-peak output swing for a supply voltage of 3.3volts in 0.18u technology.
i applied differential input of 250mV at input but at output step size i got is 246mV
only for the capacitors ratio of 1.
can anyone help me what may be the problem
 

switch cap integrator

what is ur input frequency
 

switch cap integrator

u should get two kinds of errors:
1-DC gain error: error due to open loop DC

2-Settling error:
a-linear settling error
b-slewing error

so try to decrease the frequency and see what is ur DC error, if it is negligable then it is the settling error, so try to see if the problem is in linear settling or slewing
 

Re: switch cap integrator

i feel the error is mainly due to your open loop dc gain of your opamp. your ugb is excellent. i would advise you to first put an ideal opamp in place of your original opamp. increase the ideal opamp gain to greater than 75dB i hope you will achieve close to 250mV (but never exactly 250mV).
 

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