INPUT DRIVE CONTROL FOR SWITCHER REGULATED POWER AMPLIFIER MODULES

• US 20070291872A1
• Filed: 06/14/2007
• Published: 12/20/2007
• Est. Priority Date: 06/14/2006
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Research In Motion Limited (Blackberry Limited)
• Inventors: Chan, Wen-Yen, Khan, Nasserullah
• Granted Patent: US 7,873,119 B2
• Time in Patent Office: Days
• US Class Current: 375/297
• CPC Class Codes: H03F 1/02 Modifications of amplifiers to raise the efficiency, e.g. gliding Class A stages, use of an auxiliary oscillation
• CPC Class Codes: H03F 1/0227 using supply converters
• CPC Class Codes: H03F 1/34 Negative-feedback-circuit arrangements with or without positive feedback H03F1/02 - H03F1/30, H03F1/38 - H03F1/50, H03F3/50 take precedence ; for rejection of common mode signals H03F3/45479
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03G 11/00 Limiting amplitude; Limiting rate of change of amplitude ; Clipping in general
• CPC Class Codes: H03G 3/004 Control by varying the supply voltage
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H03G 7/04 incorporating negative feedback
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 2001/0433 with linearisation using feedback
• CPC Class Codes: H04B 2001/045 with means for improving efficiency

Abstract

Various embodiments described herein relate to a power management block and an amplification block used in the transmitter of a communication subsystem. The power management block provides improved control for the gain control signal provided to a pre-amplifier and the supply voltage provided to a power amplifier which are both in the amplification block. The power expended by the power amplifier is optimized by employing a continuous control method in which one or more feedback loops are employed to take into account various characteristics of the transmitter components and control values.

Claims

1. A transmitter for a wireless communications device, wherein the transmitter comprises:

a power amplification block comprising;

a pre-amplifier configured to amplify a transmission signal to produce a pre-amplified transmission signal; and

a power amplifier coupled to the pre-amplifier and configured to amplify the pre-amplified transmission signal to produce an amplified transmission signal; and

a power management block comprising;

a power supply block configured to generate and provide a supply voltage signal and to the power amplifier; and

a compensating control block configured to adjust an automatic gain control (AGC) signal for controlling pre-amplifier gain, the compensating control block being coupled to the output of the power supply block to generate a gain correction signal based on the supply voltage signal to modify the AGC signal.

2. The transmitter of claim 1, wherein the compensating control block comprises a compensating transfer function adapted to produce the gain correction signal from the supply voltage signal and maintain a substantially linear relationship between the AGC signal and amplified transmission signal power and postpone saturation effects of the relationship.

3. The transmitter of claim 1, wherein the power management block further comprises a power limit control block configured to anticipate and correct an over-power condition by modifying the pre-amplifier gain.

4. The transmitter of claim 3, wherein the power management block further comprises a detector coupled to the output of the pre-amplifier to provide a detected pre-amp output signal and the power limit control block is configured to provide a gain control signal to the pre-amplifier to limit the transmission power of the power amplification block, the gain control signal being based on the detected pre-amp output signal, a transmit power limit signal and the modified AGC signal.

5. The transmitter of claim 4, wherein the modified AGC signal is produced by subtracting the gain correction signal from the AGC signal.

6. The transmitter of claim 5, wherein the power limit control block comprises:

a clipper configured to produce a clipped power error signal by converting negative values of a power error signal to zero and multiplying positive values of the power error signal by an adjustment factor, the power error signal being produced by subtracting the transmit power limit signal from the detected pre-amp output signal;

an integrator configured to integrate the clipped power error signal to produce an integrated power error signal; and

a power limiting transfer function configured to process the integrated power error signal to detect the over-power condition before this condition occurs and to generate an error signal,

wherein the gain control signal is generated by subtracting the error signal from the modified AGC signal.

7. The transmitter of claim 6, wherein the detector is one of a linear root mean square (RMS) detector and a non-RMS detector.

8. A mobile communication device comprising:

a main processor configured to control the operation of the mobile communication device;

a communication subsystem connected to the main processor, the communication subsystem being configured to send and receive data, the communication subsystem comprising;

a power amplification block comprising a pre-amplifier configured to amplify a transmission signal to produce a pre-amplified transmission signal; and

a power amplifier coupled to the pre-amplifier and configured to amplify the pre-amplified transmission signal to produce an amplified transmission signal; and

a power management block comprising a power supply block configured to generate and provide a supply voltage signal and to the power amplifier; and

a compensating control block configured to adjust an automatic gain control (AGC) signal for controlling pre-amplifier gain, the compensating control block being coupled to the output of the power supply block to generate a gain correction signal based on the supply voltage signal to modify the AGC signal.

9. The mobile communication device of claim 8, wherein the compensating control block comprises a compensating transfer function adapted to produce the gain correction signal from the supply voltage signal and maintain a substantially linear relationship between the AGC signal and amplified transmission signal power and postpone saturation effects of the relationship.

10. The mobile communication device of claim 8, wherein the power management block further comprises a power limit control block configured to anticipate and correct an over-power condition by modifying the pre-amplifier gain.

11. The mobile communication device of claim 10, wherein the power management block further comprises a detector coupled to the output of the pre-amplifier to provide a detected pre-amp output signal and the power limit control block is configured to provide a gain control signal to the pre-amplifier to limit the transmission power of the power amplification block, the gain control signal being based on the detected pre-amp output signal, a transmit power limit signal and the modified AGC signal.

12. The mobile communication device of claim 11, wherein the modified AGC signal is produced by subtracting the gain correction signal from the AGC signal.

13. The mobile communication device of claim 12, wherein the power limit control block comprises:

a clipper configured to produce a clipped power error signal by converting negative values of a power error signal to zero and multiplying positive values of the power error signal by an adjustment factor, the power error signal being produced by subtracting the transmit power limit signal from the detected pre-amp output signal;

an integrator configured to integrate the clipped power error signal to produce an integrated power error signal; and

a power limiting transfer function configured to process the integrated power error signal to detect the over-power condition before this condition occurs and to generate an error signal,

wherein the gain control signal is generated by subtracting the error signal from the modified AGC signal.

14. The mobile communication device of claim 11, wherein the detector is one of a linear root mean square (RMS) detector and a non-RMS detector.

15. A method of controlling gain of a power amplification block of a transmitter, the power amplification block including a pre-amplifier and a power amplifier, wherein the method comprises:

generating and providing a supply voltage signal and to the power amplifier;

generate a gain correction signal based on the supply voltage signal; and

modifying an automatic gain control (AGC) signal for controlling pre-amplifier gain based on the gain correction signal.

16. The method of claim 15, wherein the method further comprises using a compensating transfer function to produce the gain correction signal from the supply voltage signal and maintain a substantially linear relationship between the AGC signal and output power of the power amplifier and postpone saturation effects of the relationship.

17. The method of claim 15, wherein the method further comprises anticipating and correcting an over-power condition by modifying the pre-amplifier gain.

18. The method of claim 17, wherein the method further comprises detecting the output of the pre-amplifier to provide a detected pre-amp output signal and providing a gain control signal to the pre-amplifier to limit the transmission power of the power amplification block, the gain control signal being based on the detected pre-amp output signal, a transmit power limit signal and the modified AGC signal.

19. The method of claim 18, wherein the method further comprises producing the modified AGC signal by subtracting the gain correction signal from the AGC signal.

20. The method of claim 19, wherein the method further comprises:

producing a power error signal by subtracting the transmit power limit signal from the detected pre-amp output signal;

clipping the power error signal to produce a clipped power error signal by converting negative values of the power error signal to zero and multiplying positive values of the power error signal by an adjustment factor;

integrating the clipped power error signal to produce an integrated power error signal;

processing the integrated power error signal with a power limiting transfer function to detect the over-power condition before this condition occurs and to generate an error signal; and

generating the gain control signal by subtracting the error signal from the modified AGC signal.

21. The method of claim 18, wherein the method comprises using one of a linear root mean square (RMS) detector and a non-RMS detector.