Question 30.6: Suppose perfect switches are available for the circuit of Fi......

CMOS Circuit Design, Layout, and Simulation [1366182]

Suppose perfect switches are available for the circuit of Fig. 30.26. Estimate the residual offset voltage in terms of the op-amp’s gain, $A_G$ , from the auxiliary port to the op-amp output.

30.26

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If the offset voltage before reduction is $V_{OS}$ , then the offset voltage after reduction is $V_{OS}/A_G$ . For reasonable values of $A_G$ the final inherent offset voltage is negligible. The point of this example is that the charge injection and capacitive feedthrough from the switches is the dominant source of offset error using this technique.

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