joskin
Member level 1
I'm designing a 1-bit sigma-delta modulator. I find the differential voltage at the OPAMP input is greater than √2 * (VGS-VTH) at the begining of integration phase, which is caused by the big difference between input voltage and feedback voltage. As you know, this will cause slewing, and hence distortion. The big difference between input voltage and feedback voltage is inherent in a 1-bit sigma-delta modulator. My question is how to avoid the slewing? If the slewing is inevitable, what's the criteria of designing the OPAMP used in the modulator?