Power amplifier

A power amplifier comprising:

• a semiconductor substrate;
• a preceding-stage amplifying device on the semiconductor substrate, amplifying an input signal;
• a following-stage amplifying device on the semiconductor substrate, amplifying an output signal of the preceding-stage amplifying device;
• a preceding-stage bias circuit supplying bias currents to an input terminal of the preceding-stage amplifying device;
• a following-stage bias circuit supplying bias currents to an input terminal of the following-stage amplifying device;
• and
• an inter-stage matching circuit connected between an output terminal of the preceding-stage amplifying device and the input terminal of the following-stage amplifying device, wherein
• the preceding-stage amplifying device includes a first field effect transistor that is an enhancement mode or a depletion mode field effect transistor including a source, a gate, and a drain,
• the following-stage amplifying device includes a heterojunction bipolar transistor, and
• the inter-stage matching circuit includes a capacitance which galvanically separates the output terminal of the preceding-stage amplifying device from the input terminal of the following-stage amplifying device.