RECEIVER CIRCUIT AND RADIO COMMUNICATION TERMINAL APPARATUS

摘要

A low-noise amplifier (70) comprises a low-gain low-noise amplifier (71) and a high-gain low-noise amplifier (72) that can be selectively activated by the control of a bias current. The output of the low-noise amplifier (72) is coupled to a quadrature demodulator (80) via a series capacitor (73), while the output of the low-noise amplifier (71) is directly coupled to the quadrature demodulator (80). A control part (66) controls a receiver circuit in such a manner that it activates the low-noise amplifier (71) when a received signal exhibits a high level and that it activates the low-noise amplifier (72) when a received signal exhibits a low level. During operation of the low-noise amplifier (72), the DC bias current therefor is caused to flow independently of the DC bias current for the quadrature demodulator (80). During operation of the low-noise amplifier (71), the DC bias current therefor is also used for the quadrature demodulator.