Abstract: A first envelope detector circuit and a second envelope detector circuit are the same in circuit configuration, where the former detects an input high frequency signal, and the latter generates a reference voltage for power level detection. A detector detects an output voltage of a selector configured to select an output of the first envelope detector circuit with reference to an output voltage of a selector configured to select an output of the second envelope detector circuit. A controller controls an input selector to determine and store control values for the two selectors during input of a high frequency reference signal generated by a high frequency reference signal generating unit, and controls the two selectors by using the stored control values when an actual high frequency signal is input.

Abstract: A cascode amplification unit includes a plurality of cascode amplifiers connected in parallel. Each of the cascode amplifiers has two transistors. A cascode current source unit includes a plurality of cascode current sources connected in parallel. Each of the cascode current sources has two transistors. Both the output end of the cascode amplification unit and the output end of the cascode current source unit are connected to a load circuit. The control circuit turns on and off each cascode transistor of the cascode amplifier and each cascode transistor of the cascode current source so that an amount of current passing through the load circuit is constant.

Abstract: A cascode amplification unit includes a plurality of cascode amplifiers connected in parallel. Each of the cascode amplifiers has two transistors. A cascode current source unit includes a plurality of cascode current sources connected in parallel. Each of the cascode current sources has two transistors. Both the output end of the cascode amplification unit and the output end of the cascode current source unit are connected to a load circuit. The control circuit turns on and off each cascode transistor of the cascode amplifier and each cascode transistor of the cascode current source so that an amount of current passing through the load circuit is constant.

Abstract: First and second envelope detector circuits have, respectively, a resistance row, a capacitative element connected to the resistance row in parallel and a transistor connected between a connection point between the resistance row and the capacitative element and a predetermined voltage node. An output of a level shifter is supplied to a gate or a base of the transistor of the first envelope detector circuit. A predetermined voltage is supplied to a gate or a base of the transistor of the second envelope detector circuit. A detector detects an intermediate terminal voltage of the resistance row of the first envelope detector circuit with reference to a total voltage or an intermediate terminal voltage of the resistance row of the second envelope detector circuit.

Abstract: In a high-frequency amplifier for amplifying transmission and reception signals, an integrated circuit area is reduced to reduce production costs. A high-frequency amplifier (101) includes a reception signal amplifying part (102), a transmission signal amplifying part (103), and a spiral inductor (104). An output of the reception signal amplifying part (102) is connected with an output of the transmission signal amplifying part (103) to be an output terminal OUT of the high-frequency amplifier (101). The single spiral inductor (104) is connected to the output terminal OUT. This spiral inductor (104) is used as a load common to the reception signal amplifying part (102) and the transmission signal amplifying part (103). Thereby, the area of the integrated circuit is reduced, and the production cost is reduced.

Abstract: First and second envelope detector circuits have, respectively, a resistance row, a capacitative element connected to the resistance row in parallel and a transistor connected between a connection point between the resistance row and the capacitative element and a predetermined voltage node. An output of a level shifter is supplied to a gate or a base of the transistor of the first envelope detector circuit. A predetermined voltage is supplied to a gate or a base of the transistor of the second envelope detector circuit. A detector detects an intermediate terminal voltage of the resistance row of the first envelope detector circuit with reference to a total voltage or an intermediate terminal voltage of the resistance row of the second envelope detector circuit.

Abstract: In a high-frequency amplifier for amplifying transmission and reception signals, an integrated circuit area is reduced to reduce production costs. A high-frequency amplifier (101) includes a reception signal amplifying part (102), a transmission signal amplifying part (103), and a spiral inductor (104). An output of the reception signal amplifying part (102) is connected with an output of the transmission signal amplifying part (103) to be an output terminal OUT of the high-frequency amplifier (101). The single spiral inductor (104) is connected to the output terminal OUT. This spiral inductor (104) is used as a load common to the reception signal amplifying part (102) and the transmission signal amplifying part (103). Thereby, the area of the integrated circuit is reduced, and the production cost is reduced.