Patent ID: 7911280
Filing Date: 2011-03-22
Classification: H03F

Abstract:
1. An amplifier stage for generating an amplified output signal at an output terminal of the amplifier stage from an input signal at an input terminal of the amplifier stage, the amplifier stage comprising: a first active device having a first terminal, a second terminal, and a control input controlling a current between the first terminal and the second terminal of the first active device, the control input of the first active device being coupled to the input terminal of the amplifier stage, a second active device having a first terminal, a second terminal, and a control input controlling a current between the first terminal and the second terminal of the second active device, the first terminal of the second active device being coupled to the second terminal of the first active device, and the second terminal of the second active device being coupled to the output terminal of the amplifier stage, and a control circuit coupled between the control input of the second active device and the input terminal of the amplifier stage, the control circuit being adapted to force a voltage at the second terminal of the first active device to follow the input voltage at the control input of the first active device, and wherein the control circuit comprises a complementary JFET source follower composed of a p-channel junction field effect transistor and an n-channel junction field effect transistor, wherein a source terminal of the p-channel transistor is coupled to the control input of the second active device, a source terminal of the n-channel transistor is coupled to the control input of the second active device, a gate terminal of the p-channel transistor is coupled to the input terminal of the amplifier stage, and a gate terminal of the n-channel transistor is coupled to the input terminal of the amplifier stage.