Patent ID: 6577185
Filing Date: 2003-06-10
Classification: H03F,H03J,H03L

Abstract:
An operational amplifier for a pipeline analog-to-digital converter (ADC), the operational amplifier comprising:a cascaded chain of differential amplifiers, each differential amplifier including resistive-averaged common mode feedback to produce an inherent common mode voltage for the differential amplifier, a particular differential amplifier of the chain having the highest gain of the gains of the differential amplifiers; one or more feedback paths each including a compensation capacitor to compensate the operational amplifier; and one or more switches controlled by a control signal to switch on or off the differential amplifiers of the chain other than the highest-gain differential amplifier of the chain; such that the power consumption of the operational amplifier is reduced by turning off the differential amplifiers other than the highest-gain differential amplifier while the dynamic response of the operational amplifier is not compromised by the highest-gain differential amplifier being turned on or off.