High-frequency power amplifier

A high-frequency power comprising:

• a plurality of high-frequency amplifier sections, each being composed of bipolar transistors;
• a plurality of capacitors each corresponding to one of said high-frequency power amplifier sections, one end of each capacitor being connected to bases of the bipolar transistors of the corresponding high-frequency power amplifier section, and the other end thereof being connected to a high-frequency signal source;
• and
• a plurality of bias circuits each corresponding to one of said high-frequency power amplifier sections, applying a bias voltage to the bases of the bipolar transistors of the corresponding high-frequency power amplifier section,
• wherein each bias circuit is located close to the corresponding one of said high-frequency power amplifier sections, and includes a bias voltage lowering section lowering the bias voltage in response to an increase in temperature of the bipolar transistors, and
• wherein said bias voltage lowering section includes a diode connected to the bases of the bipolar transistors via resistor to block a high-frequency signal.

A high-frequency power amplifier comprising:

• a plurality of high-frequency amplifier sections, each being composed of bipolar transistors;
• a plurality of capacitors each corresponding to one of said high-frequency power amplifier sections, one end of each capacitor being connected to bases of the bipolar transistors of the corresponding high-frequency power amplifier section, and the other end thereof being connected to a high-frequency signal source;
• a plurality of bias circuits each corresponding to one of said high-frequency power amplifier sections, applying a bias voltage to the bases of the bipolar transistors of the corresponding high-frequency power amplifier section;
• and
• a voltage generating circuit having a first diode, of which a cathode is grounded, a second diode, of which a cathode is connected to the first diode and an anode is connected to a control power supply via a control resistor, and a bipolar transistor, of which a collector is connected to a bias power supply, a base is connected to the anode of the second diode, and an emitter is grounded via a resistor, the emitter of the bipolar transistor supplying said bias voltage to said bias circuits via ballast resistors,
• wherein each bias circuit is located close to the corresponding one of said high-frequency power amplifier sections, and includes a bias voltage lowering section lowering the bias voltage in response to an increase in temperature of the bipolar transistors.

A high-frequency power amplifier comprising:

• a plurality of high-frequency amplifier sections, each being composed of bipolar transistors;
• a plurality of capacitors each corresponding to one of said high-frequency power amplifier sections, one end of each capacitor being connected to bases of the bipolar transistors of the corresponding high-frequency amplifier section, and the other end thereof being connected to a high-frequency signal source;
• and
• a plurality of bias circuits each corresponding to one of said high-frequency power amplifier sections, applying a bias voltage to the bases of the bipolar transistors of the corresponding high-frequency power amplifier section,
• wherein each of said bias circuits has a first impedance when a base current supplied to the bases of the bipolar transistors in the corresponding high-frequency power amplifier section does not exceed a predetermined value, and has a second impedance larger than said first impedance when said base current exceeds said predetermined value so that said bias voltage becomes zero volts.