Patent ID: 7248115
Filing Date: 2007-07-24
Classification: H03F

Abstract:
1. A differential amplifier comprising: a differential amplifier circuit comprising first and second differential amplifier sections; wherein said first differential amplifier section comprises: a first differential pair of PMOS transistors which receives first and second input voltages, respectively; wherein said second differential amplifier section comprises: a second differential pair of NMOS transistors which receive said first and second input voltages, respectively; a bias circuit which only activates only one of said first and second differential amplifier sections in response to a control signal; and an output circuit which outputs an output signal from an output of said activated differential amplifier section, wherein said first and second differential amplifier sections comprise a first PMOS transistor and a first NMOS transistor function as constant current sources, respectively, said bias circuit stops an operation of said first PMOS transistor when activating said second differential amplifier section, and stops an operation of said first NMOS transistor when activating said first differential amplifier section.