Patent ID: 8471755

Claim:
An analog-to-digital converter (ADC), comprising: a first plurality of capacitors, each of the first plurality of capacitors having a first plate and a second plate; a set of first switches, each of the first switches coupling each of the first plates of the first plurality of capacitors to an input terminal for receiving an input voltage responsive to each of the first switches being turned on; a second switch selectively coupling the second plates of the first plurality of capacitors to a voltage source at a first reference voltage; a comparator having a first input terminal and a second input terminal, the first input terminal coupled to the second plates of the first plurality of capacitors, and the comparator configured to generate an output based on a voltage difference between the first input terminal and the second input terminal; and a frame capacitor comprising a conductive frame at least partially surrounding at least part of the first plurality of capacitors to form capacitance between the conductive frame and the second plates of the first plurality of capacitors, the frame capacitor configured to receive charge from the first plurality of capacitors to set a voltage of the first input terminal of the comparator to a predetermined level responsive to turning off the first and second switches.