Patent ID: 7795965

Claim:
A cryogenic receiving amplifier to be used in a cryogenic temperature environment, comprising: a gallium nitride high electron mobility transistor serving as an amplifying device; an input matching circuit for making impedance matching between a gate of the amplifying device and an outside of an input terminal of the cryogenic receiving amplifier; a gate biasing circuit for applying a DC voltage to the gate of the amplifying device; an output matching circuit for making impedance matching between a drain of the amplifying device and an outside of an output terminal of the cryogenic receiving amplifier; and a drain biasing circuit for applying a DC voltage to the drain of the amplifying device, wherein said cryogenic receiving amplifier further includes light illuminating means for illuminating the gallium nitride high electron mobility transistor with light containing at least a light component having a wavelength corresponding to a band gap of gallium nitride.