Hi
I want to use an OTA integrator in a dual slope ADC. But since the input signal is large signal wont it change the gm for different levels?
Thanks
Salil
If the input signal stays within the Input Common Mode Range (ICMR), and this ICMR range is defined by a gain loss of e.g. -1dB (see the PDF below, -3dB in that case), the variation should also stay within this range (-11% in this case).
If it's the common inverting integrator with a capacitor from output to the minus input and the plus input is to common, then the input CM voltage is zero and the ICMR isn't a factor. Also with the typical high open-loop gain of an OTA, any change in gm would have no significant effect on the closed-loop signal.