Patent ID: 8026760

Claim:
A method of operating a circuit in response to a pair of differential signals in which the circuit has a first differential amplifier, a second differential amplifier, a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor, wherein a first terminal of the first capacitor is coupled to a plus input of the first differential amplifier; a first terminal of the second capacitor is coupled to a minus input of the first differential amplifier; a first terminal of the third capacitor is coupled to a minus output of the second differential amplifier; a first terminal of the fourth capacitor is coupled to a plus output of the second differential amplifier; the method comprising: during a sampling mode of the circuit: coupling a first signal of the pair of differential signals to a second terminal of the first capacitor; coupling a second signal of the pair of differential signals to a second terminal of the second capacitor; coupling the plus input of the first differential amplifier to a second terminal of the fourth capacitor; coupling the minus input of the first differential amplifier to a second terminal of the third capacitor; coupling a plus output of the first differential amplifier to a minus input of the second differential amplifier; and coupling a minus output of the first differential amplifier to a plus input of the second differential amplifier; and during a hold mode of the circuit: decoupling the first signal from the second terminal of the first capacitor; decoupling the second signal from the second terminal of the second capacitor; decoupling the plus input of the first differential amplifier from the second terminal of the fourth capacitor; decoupling the minus input of the first differential amplifier from the second terminal of the third capacitor; decoupling the plus output of the first differential amplifier from the minus input of the second differential amplifier; decoupling the minus output of the first differential amplifier from the plus input of the second differential amplifier; coupling the second terminal of the first capacitor to the minus output of the second differential amplifier; coupling the second terminal of the second capacitor to the plus output of the second differential amplifier; coupling the second terminal of the fourth capacitor to a reference terminal; coupling the second terminal of the third capacitor to the reference terminal; coupling the plus output of the first differential amplifier to the plus input of the second differential amplifier; and coupling the minus output of the first differential amplifier to the minus input of the second differential amplifier.