Low bias current/temperature compensation current mirror for linear power amplifier

• US 20030006845A1
• Filed: 07/29/2002
• Published: 01/09/2003
• Est. Priority Date: 08/10/1999
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Anadigics Incorporated (Coherent Corp.)
• Inventors: Lopez, Osvaldo Jorge, Singh, Mahendra, Bayruns, Robert
• Granted Patent: US 6,937,102 B2
• Time in Patent Office: Days
• US Class Current: 330/289
• CPC Class Codes: H03F 1/0272 by using a signal derived from the output signal
• CPC Class Codes: H03F 1/301 in MOSFET amplifiers H03F1/303, H03F1/305, H03F1/308 take precedence
• CPC Class Codes: H03F 2200/18 the bias of the gate of a FET being controlled by a control signal
• CPC Class Codes: H03F 2200/504 the supply voltage or current being continuously controlled by a controlling signal, e.g. the controlling signal of a transistor implemented as variable resistor in a supply path for, an IC-block showed amplifier
• CPC Class Codes: H03F 2200/99 A diode as rectifier being used as a detecting circuit in an amplifying circuit

Abstract

A power amplifier circuit whose performance is optimized by operating its stages in substantially close to a Class B mode by reducing quiescent current during low driver signal levels. As the driver signal amplitude increases, the operation of the amplifier is configured to dynamically adjust to be in a Class AB mode, thereby increasing the power efficiency of the overall circuit at kiw drive levels. A further enhancement to the power amplifier circuit includes a temperature compensation circuit to adjust the bias of the amplifier so as to stabilize the performance in a wide temperature range.

Claims

1. An amplifying circuit comprising:

an amplifying device; and

a dynamic bias adjustor for biasing said amplifying device configured to operate said amplifying device in a Class B mode or substantially close to a Class B mode during low drive level conditions, and a Class AB mode during high drive level conditions.

2. The amplifying circuit as in claim 1, further comprising a temperature compensation circuit to stabilize the bias, point of said amplifying device over a temperature range.

3. The amplifying circuit as in claim 2, wherein the temperature range is between −

30°

C. and +110°

C.

4. A method of biasing an amplifying circuit comprising a pre-amplifier stage, a driver stage and an output stage, the method comprising the steps of:

detecting a driver output alternating voltage at the driver stage;

applying to a dynamic bias adjustor a voltage proportional to the driver output voltage; and

applying the output voltage of the dynamic bias adjustor to bias the stages of the amplifying circuit whereby at least one of the stages of the amplifying circuit operates in a Class B mode or substantially close to a Class B when the driver output current is at or below a predetermined level.

6. The method of claim 6, further comprising the step of stabilizing the bias point of at least one of the stages to account for changes in temperature.

5. The method of claim 6, further comprising the step of changing the bias voltage applied to at least one of the stages of the amplifying circuit in order to operate said at least one of the stages of the amplifying circuit in a Class AB mode when the driver output current is at or above a predetermined level.