Patent ID: 7714664

Claim:
A cascode circuit including two cascode-connected transistors, comprising: a first transistor including, as a first terminal, one of a source and an emitter, the first terminal being grounded, and, as a second terminal, one of a drain and a collector; a second transistor including, as a first terminal, one of a source and an emitter, the first terminal being connected to the second terminal of the first transistor, as a second terminal, one of a gate and a base, and, as a third terminal, one of a drain and a collector; a signal improving circuit connected to the second terminal of the second transistor, for improving and outputting an input signal input to the signal improving circuit; and a filter circuit connected to a side of the signal improving circuit which is opposite a side of the signal improving circuit that is connected to the second transistor, for short-circuiting high-frequency signals at a predetermined frequency, including at frequencies near the predetermined frequency.