Patent ID: 8605521

Claim:
An apparatus, comprising: a first differential amplifier having first and second amplifier input nodes and an amplifier output node, the first differential amplifier configured to amplify a voltage difference between voltages applied to the first and second amplifier input nodes to provide an output at the amplifier output node; a second differential amplifier having an amplifier input node coupled to the amplifier output node of the first differential amplifier; first and second capacitances coupled to the first and second amplifier input nodes of the first differential amplifier, respectively; third and fourth capacitances coupled to the first and second amplifier inputs of the second differential amplifier; a first switch block having first and second switch block input nodes, and a reference input node, the first switch block further having first and second switch block output nodes coupled to the first and second capacitances, the first switch block configured to couple during a first phase the reference input node to the first and second capacitances and the reference input node to the first amplifier input node, and configured to couple during the first phase the amplifier output node to the second amplifier input node to establish a compensation condition, the first switch block further configured to couple during a second phase the first and second switch block input nodes to the first and second capacitances, respectively; and a second switch block having first and second switch block input nodes, and a reference input node, and a feedback input node, the second switch block further having first and second switch block output nodes coupled to the third and fourth capacitances, the second switch block input node coupled to the amplifier output node of the first differential amplifier and the amplifier output node of the second differential amplifier coupled to the feedback input node of the second switch block.