Patent ID: 7579909
Filing Date: 2009-08-25
Classification: H03F

Abstract:
1. An amplifier circuit comprising: an amplifier comprising an input terminal and an output terminal; and a phase shifter comprising an input terminal coupled to the input terminal of the amplifier, and an output terminal coupled to the output terminal of the amplifier, wherein the phase shifter is switchable such that the phase shifter has a first impedance for an alternating signal in an “on” state and has a second impedance for the alternating signal in an “off” state, the second impedance being higher than the first impedance, wherein the phase shifter comprises two capacitances in series, the two capacitances connected in parallel to the amplifier, and an inductance that is connected with a first terminal to a circuit node between the two capacitances and is connected with a second terminal to a switch so that the second terminal of the inductance is connected to a reference potential when the switch is closed.