An arrangement for biasing the gate of a transistor in the low noise amplifier of a receiver to protect the transistor from an excessive input

摘要

A circuit for controlling a low-noise amplifier having a low-noise transistor as an amplifying device, includes a bias voltage controller (5) (fig 1) decreasing a voltage to be applied to a gate of the transistor down to a voltage equal to or smaller than a pinch-off voltage to thereby pinch-off the low-noise amplifier (3), while power to be provided to the low-noise amplifier (3) is inhibited. Even if an excessive input signal is input into the low-noise amplifier while the low-noise amplifier is not in operation, gate current does not flow through the transistor constituting the low-noise amplifier. Hence, it is possible to minimise the likelihood that the device will be destroyed.