Amplifier and semiconductor device therefor

A semiconductor device for an amplifier, said amplifier comprising:

• signal-amplifying field-effect transistors at least in two stages connected in cascade from the input side to the output side of an amplification signal so as to have a configuration wherein the main electrode of said signal-amplifying field-effect transistor in a former stage is connected to the control portion of said signal-amplifying field-effect transistor in the next stage at least via a coupling capacitor;
• a gain control circuit, the control input end of which is connected to a gain control signal input portion for inputting a gain control signal, and the control output end of which is connected to the control portion of a signal-amplifying field-effect transistor at least in one stage other than the final stage, among said signal-amplifying field-effect transistors at least in two stages, being capable of controlling the gain of said signal-amplifying field-effect transistor at least in one stage other than the final stage in accordance with said gain control signal;
• and
• a bias voltage control circuit, the control output end of which is connected to the control portion of a signal-amplifying field-effect transistor at least in one stage after a signal-amplifying field-effect transistor whose control portion is connected to said control output end of said gain control circuit, by the electrical connection to said gain control circuit, being capable of reducing the main current of said signal-amplifying field-effect transistor at least in one stage after said signal-amplifying field-effect transistor whose control portion is connected to said control output end of said gain control circuit at the time when the gain of said signal-amplifying field-effect transistor at least in one stage other than the final stage is lowered,
• wherein said amplifier is integrated on a semiconductor substrate, sealed in a package, and provided on said package with external terminals:
• a signal input terminal for inputting an amplification signal to said control portion of said signal-amplifying field-effect transistor at least in the first stage, a signal output terminal for outputting said amplification signal from the main electrode of said signal-amplifying field-effect transistor in the final stage and a gain control terminal for inputting said gain control signal to said gain control signal input portion.

A semiconductor device including an amplifier, said amplifier comprising:

• signal-amplifying field-effect transistors at least in two stages connected in cascade from the input side to the output side of an amplification signal so as to have a configuration wherein a signal from the main electrode of said signal-amplifying field-effect transistor in a former stage is received by a control portion of said signal-amplifying field-effect transistor in a latter stage,
• a gain control circuit which has a first control input end connected to a gain control signal input portion for inputting a gain control signal and a first control output end connected to the control portion of a signal-amplifying field-effect transistor at least in said former stage and which is capable of controlling the gain of said signal-amplifying field-effect transistor in said former stage in accordance with said gain control signal;
• and
• a bias voltage control circuit which has a second control input end connected to said gain control signal input portion and a second control output end connected to said control portion of said signal-amplifying field-effect transistor in said latter stage and which is capable of controlling a main current of said signal-amplifying field-effect transistor in said latter stage according to said gain control signal, wherein the main current of said signal amplifying field-effect transistor in said latter stage is reduced when the gain of said signal-amplifying field-effect transistor in said former stage is lowered;
• a semiconductor substrate having said amplifier integrated thereon so as to be scaled in a package having, as external terminals, a signal input terminal for inputting an amplification signal to said control portion of said signal-amplifying field-effect transistor at least in said first stages a signal output terminal for outputting said amplification signal from the main electrode of said signal-amplifying field-effect transistor in said final stage, and a gain control terminal for inputting said gain control signal to said gain control signal input portion.

An amplifier comprising:

• signal-amplifying field-effect transistors at least in two stages connected in cascade from the input side to the output side of an amplification signal so as to have a configuration wherein a signal from the main electrode of said signal-amplifying field-effect transistor in a former stage is received by a control portion of said signal-amplifying field-effect transistor in a latter stage;
• a gain control circuit which has a first control input end connected to a gain control signal input portion for inputting a gain control signal and a first control output end connected to the control portion of a signal-amplifying field-effect transistor at least in said former stage and which is capable of controlling the gain of said signal-amplifying field-effect transistor in said former stage in accordance with said gain control signal;
• and
• a bias voltage control circuit which has a second control input end and a second control output end connected to said control portion of said signal-amplifying field-effect transistor in said latter stage and which is capable of controlling a main current of said signal-amplifying field-effect transistor in said latter stage according to said gain control signal, wherein the main current of said signal amplifying field-effect transistor in said latter stage is reduced when the gain of said signal-amplifying field-effect transistor in said former stage is lowered, wherein said bias voltage control circuit comprises a series connection circuit comprising a voltage-dividing resistor and a voltage-dividing field effect transistor connected between a bias voltage application portion and a grounding point, said control portion of said voltage-dividing field effect transistor is used as said second control input end of said bias voltage control circuit, and the connection point of said voltage-dividing resistor and said voltage-dividing field effect transistor is used as said second control output end of said bias voltage control circuit.