Switched-capacitor network with input-output common mode decoupling

摘要

Various embodiments of the invention provide for cancellation of unwanted signals in switched-capacitor circuits. In certain embodiments cancellation this is accomplished by performing a multi-phase CDS technique. The technique comprises resetting capacitive elements in the feedback path of an operational amplifier during a reset interval, maintaining a decoupled condition during a sampling interval in which the unwanted signals are sampled, and cancelling unwanted signals in a sensing interval.

主权项

1. A switched-capacitor network to cancel unwanted signals, the switched-capacitor network comprising:
first and second reset switches coupled to a respective input common mode voltage and an output common mode voltage; an operational amplifier having an input terminal and an output terminal that in a reset phase are selectively connected to receive the input common mode voltage and the output common mode voltage, respectively; a CDS capacitor coupled between first and second reset switches to decouple the input common mode voltage from the output common mode voltage in a CDS phase; a sensing capacitor coupled in series with a sensing switch across the operational amplifier in a feedback loop, the sensing capacitor configured to store in a sensing phase a charge associated with an unwanted signal; a first CDS switch coupled to the sensing capacitor; and a second CDS switch coupled between the output common mode voltage and the output terminal.