Patent ID: 6360086
Filing Date: 2002-03-19
Classification: H03G

Abstract:
A circuit adapted to receive an AC signal, and further adapted to provide an amplified AC signal as a first output, and to provide a signal representative of the magnitude of the received AC signal as a second output, comprising:an AC signal input terminal coupled to a first terminal of a first capacitor; a bias network, having one terminal coupled to a first power supply node, the bias network operable to provide current so as to produce a variable voltage at a second terminal of the bias network; a first current-controlled semiconductor device having a first terminal, a second terminal, and a third terminal, the first terminal coupled to the second terminal of the bias network and further coupled to a second terminal of the first capacitor; a first load element coupled in series between a second power supply node and the second terminal of the first current-controlled semiconductor device; and a low-pass filter, coupled between the second terminal of the current-controlled semiconductor device and the second power supply node; wherein the bias network is configured such that, in operation, the current flow in the current-controlled semiconductor device is reduced when the received AC signal is nominally zero, as compared to when the received AC signal is non-zero.