Cascode amplifier

摘要

In one embodiment, a cascode amplifier includes an amplifier circuit, a replica circuit, a bias circuit, and a feedback circuit. The amplifier circuit includes a first transistor and a second transistor. The second transistor is cascode-connected to the first transistor. The replica circuit includes a third transistor and a fourth transistor. The third transistor has a control terminal connected to a control terminal of the first transistor. The fourth transistor is cascode-connected to the third transistor. The bias circuit applies a bias voltage to a control terminal of the second transistor and a control terminal of the fourth transistor. The feedback circuit performs a feedback control of a voltage of the control terminal of the third transistor. The feedback circuit reduces the difference between a reference current and a current at a predetermined point of the replica circuit.

主权项

1. A cascode amplifier comprising:
an amplifier circuit including a first transistor and a second transistor cascode-connected to the first transistor; a replica circuit including a third transistor having a control terminal connected to a control terminal of the first transistor, and a fourth transistor cascode-connected to the third transistor; a bias circuit applying a bias voltage to a control terminal of the second transistor and a control terminal of the fourth transistor; and a feedback circuit performing a feedback control of a voltage of the control terminal of the third transistor to reduce the difference between a reference current and a current at a predetermined point of the replica circuit, wherein a ratio of a ratio of a channel width to a channel length of the third transistor to a ratio of a channel width to a channel length of the fourth transistor is equal to a ratio of a ratio of a channel width to a channel length of the first transistor to a ratio of a channel width to a channel length of the second transistor.