Patent ID: 6411166
Filing Date: 2002-06-25
Classification: H03F

Abstract:
A fully differential switched operational amplifier circuit with common-mode control, comprising:a first reference potential line and a second reference potential line respectively set at a first reference voltage and at a second reference voltage; a fully differential, switched operational amplifier alternately switchable on and off and having a first differential output and a second differential output, and a biasing control terminal; a control circuit comprising a capacitive detecting network and biasing control means, said capacitive detecting network including a first capacitive element, a second capacitive element and a third capacitive element, said first capacitive element connected between said first differential output of said operational amplifier, and a common-mode node, said second capacitive element coupled between said second differential output and said common-mode node, and said third capacitive element connected between said common-mode node and a biasing node that is connected to said first reference potential line in a first operative condition and said second reference potential line in a second operative condition, and said biasing control means having a control input connected to said common-mode node and an output connected to said control terminal of said operational amplifier, and switchable biasing means activated for biasing said common-mode node at a desired voltage in said first operative condition and deactivated in said second operative condition for leaving said common-mode node floating, said common-mode node directly connected to said biasing-control means.