Power Amplifier Bias Control

• US 20080171523A1
• Filed: 12/20/2006
• Published: 07/17/2008
• Est. Priority Date: 12/20/2006
• Status: Abandoned Application

• Current Assignee: Merz Pharma GmbH & Company Kgaa, Sony Ericsson Mobile Communications USA Incorporated (Sony Group Corp.)
• Original Assignee: Sony Ericsson Mobile Communications USA Incorporated (Sony Group Corp.)
• Inventors: Story, David Ryan, Oakley, Michael Alan, Anderson, William David
• Application Number:
  US11/613,392
• Publication Number:
  US 20080171523A1
• Time in Patent Office: Days
• US Class Current: 455/127.1
• CPC Class Codes: H03F 1/0205 in transistor amplifiers
• CPC Class Codes: H03F 1/0211 with control of the supply voltage or current
• CPC Class Codes: H03F 1/0233 by using a signal derived from the output signal, e.g. bootstrapping the voltage supply
• CPC Class Codes: H03F 1/0261 with control of the polarisation voltage or current, e.g. gliding Class A
• CPC Class Codes: H03F 1/0272 by using a signal derived from the output signal
• CPC Class Codes: H03F 2200/207 A hybrid coupler being used as power measuring circuit at the output of an amplifier circuit
• CPC Class Codes: H03F 2200/451 the amplifier being a radio frequency amplifier
• CPC Class Codes: H03F 2200/465 Power sensing
• 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

Abstract

A power amplifier circuit for a mobile terminal controls the bias voltage depending on the modulation of the input signal. The power amplifier circuit includes a power amplifier control circuit configured to control power amplifier bias for a first input signal modulation using calibrated bias control values corresponding to a range of transmit power levels, and to control power amplifier bias for said second input signal modulation using adjusted bias control values obtained by adding bias offsets to said calibrated bias control values.

Claims

1. A method of controlling bias voltage of a power amplifier, said method comprising:

controlling power amplifier bias for a first input signal modulation using calibrated bias control values corresponding to a range of transmit power levels; and

controlling power amplifier bias for said second input signal modulation using adjusted bias control values obtained by adding bias offsets to said calibrated bias control values.

2. The method of claim 1 wherein said bias offsets vary depending on a current power level of said power amplifier.

3. The method of claim 1 further comprising detecting an output power of said power amplifier, comparing said output power to a desired target output power, and controlling said power amplifier based on said comparison to maintain said output power at said target output power.

4. The method of claim 1 wherein said first bias control values are stored in a lookup table in memory.

5. A power amplifier circuit for a mobile terminal comprising:

a power amplifier;

a bias control circuit for generating a bias voltage for said power amplifier responsive to a bias control value; and

a power amplifier control circuit connected to said bias voltage control circuit for generating bias control values to control the bias voltage output by said bias voltage control circuit, said power amplifier control circuit configured to;

output calibrated bias control values corresponding to a range of transmit power levels for a first input signal modulation;

adjust said calibrated bias control values for a second input signal modulation by adding bias offsets to said calibrated bias control values; and

output said adjusted bias control values for said second input signal modulation.

6. The power amplifier circuit of claim 5 wherein said bias offsets vary depending on a current power level of said power amplifier.

7. The power amplifier circuit of claim 5 wherein said first bias control values are stored in a lookup table in memory.

8. The power amplifier circuit of claim 5 further comprising a supply voltage control circuit to apply a supply voltage to the power amplifier, wherein the power amplifier control circuit generates a control signal to control the supply voltage applied by the supply voltage control circuit to the power amplifier.

9. The power amplifier circuit of claim 8 wherein the power amplifier control circuit is operative to:

detect an output power of said power amplifier;

compare said output power to a desired target output power; and

control said supply based on said comparison to maintain said output power at said target output power.

10. A mobile terminal comprising:

a receiver;

a transmitter including a power amplifier and a bias voltage control circuit; and

a power amplifier control circuit connected to said bias voltage control circuit for generating bias control values to control the bias voltage output by said bias voltage control circuit, said power amplifier control circuit configured to;

output calibrated bias control values corresponding to a range of transmit power levels for a first input signal modulation to said bias control circuit;

adjust said calibrated bias control values for a second input signal modulation by adding bias offsets to said calibrated bias control values; and

output said adjusted bias control values for said second input signal modulation.

11. The mobile terminal of claim 10 wherein said bias offsets vary depending on a current power level of said power amplifier.

12. The mobile terminal of claim 10 wherein said first bias control values are stored in a lookup table in memory.

13. The mobile terminal of claim 10 further comprising a supply voltage control circuit to apply a supply voltage to the power amplifier, wherein the power amplifier control circuit generates a control signal to control the supply voltage applied by the supply voltage control circuit to the power amplifier.

14. The mobile terminal of claim 13 wherein the power amplifier control circuit is operative to:

detect an output power of said power amplifier;

compare said output power to a desired target output power; and

control said power amplifier based on said comparison to maintain said output power at said target output power.