POWER AMPLIFIER

• US 20140015613A1
• Filed: 03/15/2013
• Published: 01/16/2014
• Est. Priority Date: 07/11/2012
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: Sasaki, Yoshinobu
• Granted Patent: US 9,077,291 B2
• Time in Patent Office: Days
• US Class Current: 330/296
• CPC Class Codes: H03F 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• CPC Class Codes: H03F 2200/18 the bias of the gate of a FET being controlled by a control signal
• CPC Class Codes: H03F 2200/27 A biasing circuit node being switched in an amplifier circuit
• CPC Class Codes: H03F 2200/411 the output amplifying stage of an amplifier comprising two power stages
• CPC Class Codes: H03F 2203/7206 the gated amplifier being switched on or off by a switch in the bias circuit of the amplifier controlling a bias voltage in the amplifier
• CPC Class Codes: H03F 3/21 with semiconductor devices only H03F3/245 takes precedence
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H03F 3/72 Gated amplifiers, i.e. amplifiers which are rendered operative or inoperative by means of a control signal

Abstract

A power amplifier includes: an amplifier having an input terminal and including an amplifying transistor having a threshold voltage; a transistor supplying a bias to the input terminal of the amplifier according to an on/off signal; a capacitor connected between the input terminal of the amplifier and a grounding point; a resistor connected between the input terminal of the amplifier and the grounding point, in parallel with the capacitor; and a diode connected in series with the resistor. The diode has a threshold voltage that is lower than the threshold voltage of the amplifying transistor.

Claims

1. A power amplifier comprising:

an amplifier having an input terminal and including an amplifying transistor having a threshold voltage;

a transistor supplying a bias to the input terminal of the amplifier according to an on/off signal;

a capacitor connected between the input terminal of the amplifier and a grounding point;

a resistor connected between the input terminal of the amplifier and the grounding point, in parallel with the capacitor; and

a diode connected in series with the resistor, wherein the diode has a threshold voltage that is lower than the threshold voltage of the amplifying transistor.

2. A power amplifier comprising:

an amplifier having an input terminal;

a transistor supplying a bias to the input terminal of the amplifier according to an on/off signal;

a capacitor connected between the input terminal of the amplifier and a grounding point;

a resistor connected between the input terminal of the amplifier and the grounding point, in parallel with the capacitor;

a switch connected in series with the resistor; and

a control circuit maintaining the switch in an “

on”

state for a certain time period when the on/off signal is changed from an “

on”

signal to an “

off”

signal.

3. The power amplifier according to claim 2, wherein the control circuit includes a pulse generation circuit that outputs a pulse signal when the on/off signal is changed from the “

on”

signal to the “

off”

signal.

4. The power amplifier according to claim 2, wherein

the switch includes first and second switches connected in series,

the control circuit includes:

a delay circuit controlling turning on/off of the first switch by means of a signal obtained by delaying the on/off signal by a certain time period; and

an inverter controlling turning on/off of the second switch with a signal obtained by inverting the on/off signal.

5. A power amplifier comprising:

an amplifier having an input terminal;

a transistor supplying a bias to the input terminal of the amplifier according to an on/off signal;

a capacitor connected between the input terminal of the amplifier and a grounding point; and

a switch connected between the input terminal of the amplifier and the capacitor and being turned on/off according to the on/off signal.