Low noise amplifier having bypass circuitry

摘要

A low noise amplifier (10) having an amplifier mode and a bypass mode. In the amplifier mode the input signal received at an input terminal (12) is amplified by an amplifying transistor (40) and the output signal supplied at an output terminal (50). In the bypass mode the input signal is not amplified, but transferred by a bypass circuit (22) from the base to the collector of the amplifying transistor. An input impedance matching circuit (14) and an output impedance matching circuit (44), along with the bypass circuit (22) provide a constant input and output impedance when the low noise amplifier (10) operates in the amplifier mode and the bypass mode.