Patent ID: 8244195
Filing Date: 2012-08-14
Classification: H03G

Abstract:
1. A low noise amplifier circuit for a radio frequency tuner, the circuit comprising: an input stage adapted to receive a signal; an amplifier stage adapted to amplify the signal; the amplifier stage comprising two gain stages; wherein the input stage comprises a variable resistance arranged so as to permit variation of the voltage gain of the input stage; wherein the circuit further comprises a controller that varies the transconductances of one or both of the gain stages such that the ratio of the transconductances of the two gain stages is scaled responsive to the variation in the voltage gain of the input stage; and wherein a first of the gain stages amplifies and inverts both the signal and noise on the signal and a second of the gain stages amplifies and inverts both the noise on the signal and the inverted signal, such that when the outputs of the two gain stages are subtracted the signal is amplified and the noise is removed.