Patent ID: 6950052

Claim:
A single ended SAR converter front end with common mode driver noise cancellation, comprising: a differential amplifier having positive and negative inputs and an output; a switched capacitor array operable in a SAR data conversion operation to vary the voltage on one of said positive or negative inputs of said differential amplifier; a common mode driver for delivering a low impedance common mode voltage signal to a common mode node; switching circuitry for switching the common mode voltage signal on said common mode node to said positive and negative inputs of said differential amplifier during a portion of a SAR data conversion cycle; and a capacitor reference circuit attached to the other of said positive or negative inputs of said differential amplifier during at least said portion of the SAR data conversion cycle, said capacitor reference circuit and said capacitor array during at least said portion of the SAR data conversion cycle having relative capacitance values that increase the common mode rejection of any noise introduced to said common mode node at the input of said differential amplifier.