Method and apparatus for improving power amplifier efficiency in wireless communication systems having high peak to average power ratios

• US 7,333,563 B2
• Filed: 02/20/2004
• Issued: 02/19/2008
• Est. Priority Date: 02/20/2004
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Research In Motion Limited (Blackberry Limited)
• Inventors: Chan, Wen-Yen, Jiao, Qingzhong, Khan, Nasserullah, Jin, Xin, Sangary, Nagula Tharma, Habicher, Michael Franz
• Primary Examiner(s): VO, DON NGUYEN
• Application Number:
  US10/781,812
• Publication Number:
  US 20050186923A1
• Time in Patent Office: 1,460 Days
• Field of Search: 375/141, 375/219, 375/222, 375/267, 375/296, 375/297, 375/345, 370/318, 455/69, 455/127.1, 455/522
• US Class Current: 375/297
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level

Abstract

A power management system and method for a wireless communication device generates an average desired transmit power signal based on at least one of a received signal strength indicator signal and a power control instruction signal from a base station. A power supply level adjustment signal is generated based on the data parameters of an outgoing data stream and at least one environmental information signal. A combination of the power supply level adjustment signal and the average desired transmit power or a gain control signal and an altered version of the power supply level adjustment signal is used to generate a variable power supply signal that is provided to an output amplifier block for sufficiently generating outgoing wireless device radio signals while reducing power loss in the output amplifier block.

Claims

1. A power management system for providing a variable power supply signal to an output power amplifier block in a wireless communication device, the power management system comprising:

(a) an average power and gain control block for providing a gain control signal in response to at least one of a power control instruction signal and a received signal strength indicator signal and providing the gain control signal to the output power amplifier block;

(b) an environmental sensor unit for providing at least one environmental information signal;

(c) a power supply level adjustment generator connected to the environmental sensor unit for providing an altered version of a power supply level adjustment signal in response to a data parameter indication of a baseband outgoing data stream to be transmitted by the wireless communication device and the at least one environmental information signal; and

,

(d) a power supply means connected to the average power and gain control block and the power supply level adjustment generator, the power supply means provides the variable power supply signal to the output power amplifier block by providing a first power control signal based on the gain control signal and the altered version of the power supply level adjustment signal, clipping the first power control signal to provide a second power control signal

and generating the variable power supply signal based on the second power control signal,

wherein, the gain control signal is adapted for applying sufficient gain to a transmission signal version of the baseband outgoing data stream and the altered version of the power supply level adjustment signal is adapted for providing a small sufficient amount of headroom to efficiently provide power to transmit the transmission signal.

2. The power management system of claim 1, wherein the environmental sensor unit comprises at least one of:

(e) a temperature sensor for providing a temperature information signal as part of the at least one environmental information signal, the temperature information signal being related to the temperature of the hardware of the wireless communications device; and

,

(f) a battery condition sensor for providing a battery condition information signal as part of the at least one environmental information signal, the battery condition information signal being related to a battery used to power the wireless communication device.

3. The power management system of claim 1, wherein the at least one environmental information signal comprises a frequency information signal related to the frequency at which the baseband outgoing data stream will be transmitted.

4. The power management system of claim 1, wherein the average power and gain control block provides an altered version of the gain control signal and the power supply means comprises:

(g) a summer connected to the average power and gain control block and the power supply level adjustment generator for summing the gain control signal and the altered version of the power supply level adjustment signal to generate the first power control signal;

(h) a clipper connected to the summer for receiving the first power control signal and generating the second power control signal;

(i) a switch converter connected to the clipper for receiving the second power control signal and generating the variable power supply signal; and

,

(j) a reverse mapper connected to the power supply level adjustment generator and the average power and gain control block for receiving an environmental signal and the altered version of the gain control signal respectively and generating a clipper adjustment signal, the reverse mapper also being connected to the clipper for providing the clipper adjustment signal to the clipper for adjusting the positive and negative saturation values and slope of the clipper.

5. The power management system of claim 1, wherein the power supply means is configured to maintain the variable power supply signal above a minimum voltage level.

6. The power management system of claim 1, wherein the power supply level adjustment generator is implemented by a plurality of look-up tables, wherein one look-up table is provided for each environmental information signal and the data parameter indication, and the outputs of each look-up table are combined to generate the altered version of the power supply level adjustment signal.

7. The power management system of claim 6, wherein at least one of the look-up tables is implemented by a formula based on a relationship between the various inputs to the power supply level adjustment generator and the altered version of the power level adjustment signal.

8. The power management system of claim 1, wherein the system further comprises a data parameter detector connected to the power supply level adjustment generator and a baseband device of the wireless communications device, wherein the data parameter detector provides the data parameter indication.

9. The power management system of claim 1, wherein the power supply means comprises a switch converter configured to generate the second power control signal based on the second power control signal, wherein the power supply means is calibrated by:

(i) transmitting wireless device radio signals at a constant power level from the wireless communication device while monitoring an Adjacent Channel Power Ratio (ACPR);

(ii) reducing the magnitude of the variable power supply signal while maintaining constant output power in the wireless device radio signals;

(iii) recording the magnitude of the variable power supply signal when the ACPR has increased to a pre-specified design target;

(iv) increasing the output power of the wireless device radio signals and repeating steps (i) to (iii) for several output power levels; and

,

(v) computing an ideal transfer function for deriving the second power control signal for controlling the switch converter.

10. The power management system of claim 9, wherein the power supply means is further calibrated by:

(vi) repeating steps (i) to (v) for several different wireless communication devices to obtain an average transfer function; and

,

(vii) performing curve fitting on the average transfer function.

11. The power management system of claim 9, wherein the power supply level adjustment generator is calibrated by:

(viii) loading the power supply level adjustment generator with a value which causes the output power amplifier block to operate at a lowest transmission power point;

(ix) calibrating transmission power level until the output power of the output power amplifier block slightly exceeds a target power determined for a power supply voltage level;

(x) interpolating the output value of the average power level and gain control block and loading this interpolated output value, after adjustment by a reverse mapper, into the power supply level adjustment generator;

(xi) adjusting the transmission power level to a value slightly below the target power; and

,

(xii) increasing the value of the transmission power level and repeating steps (viii) to (xi) until a maximum specified transmission power point is reached.

12. The power management system of claim 1, wherein positive and negative saturation values and slope used in clipping are adjusted based on the at least one environment signal and the altered version of the gain control signal.

13. A wireless communications device comprising the power management system of claim 1.

14. A method of supplying a variable power supply signal to an output power amplifier block in a wireless communications device that receives an incoming data stream from a base station radio signal and transmits an outgoing data stream in a wireless device radio signal, the method comprising:

(a) detecting at least one of a signal strength of the base station radio signal to produce a received signal strength indicator signal, and a power control instruction signal in the base station radio signal;

(b) generating as an output a gain control signal in response to at least one of the received signal strength indicator signal and the power control instruction signal;

(c) generating at least one environmental information signal for obtaining information about the environment of the wireless communications device

(d) generating an altered version of a power supply level adjustment signal based on a data parameter indication of a baseband outgoing data stream and the at least one environmental information signal;

(e) providing a first power control signal based on the gain control signal and the altered version of the power supply level adjustment signal, clipping the first power control signal to provide a second power control signal, and generating the variable power supply signal based on the second power control signal; and

,

(f) providing the variable power supply signal and the gain control signal to the output power amplifier block, wherein, the gain control signal is adapted for applying sufficient gain to a transmission signal version of the baseband outgoing data stream and the altered version of the power supply level adjustment signal is adapted for providing a small sufficient amount of headroom to efficiently provide power to transmit the transmission signal.

15. The method of claim 14, wherein step (c) comprises at least one of:

(i) generating a temperature information signal related to the temperature of the hardware of the wireless communications device and providing the temperature information signal as part of the at least one environmental information signal;

(ii) generating a battery condition information signal related to a battery used to power the wireless communications device and providing the battery condition information signal as part of the at least one environmental information signal; and

,

(iii) generating a frequency information signal related to the frequency at which the outgoing data stream is transmitted and providing the frequency information signal as part of the at least one environmental information signal.

16. The method of claim 14, wherein step (e) comprises:

(iv) adding the altered version of the power supply level adjustment signal and the gain control signal to provide the first power control signal, the altered version of the power supply level adjustment signal being generated based on the derivation of the gain control signals.

17. The method of claim 16, wherein step (v) comprises generating an altered version of the gain control signal and providing a clipper adjustment signal to adjust positive and negative saturation values and slope used in clipping, the clipper adjustment signal being generated in response to a combination of the at least one environmental information signal and the altered version of the gain control signal.

18. The method of claim 14, wherein the method further comprises maintaining the variable power supply signal above a minimum voltage level.

19. A method of calibrating a power management system for a wireless communication device having an output power amplifier block, wherein the power management system comprises a power supply control block configured to provide a power control signal and a switch converter configured to provide a variable power supply signal to the output power amplifier block in response to the power control signal, wherein the method comprises:

(i) transmitting wireless device radio signals at a constant power level from the wireless communication device while monitoring an Adjacent Channel Power Ratio (ACPR);

(ii) reducing the magnitude of a variable power supply signal while maintaining constant output power in the wireless device radio signals;

(iii) recording the magnitude of the variable power supply signal when the ACPR has increased to a pre-specified design target;

(iv) increasing the output power of the wireless device radio signals and repeating steps (i) to (iii) for several output power levels; and

(v) computing an ideal transfer function for deriving the power control signal for controlling the switch converter.

20. The method of claim 19, wherein the method further comprises calibrating the power supply means by:

(vi) repeating steps (i) to (v) for several different wireless communication devices to obtain an average transfer function; and

,

(vii) performing curve fitting on the average transfer function.

21. The method of claim 19, wherein the power management system further comprises an average power and gain control block configured to provide a gain control signal to the output power amplifier block and an average desired transmit power signal to the power supply control block, and a power supply level adjustment generator configured to provide a power supply level adjustment signal to the power supply control block and the method further comprises:

(viii) loading the power supply level adjustment generator with a value which causes the output power amplifier block to operate at a lowest transmission power point;

(ix) calibrating transmission power level until the output power of the output power amplifier block slightly exceeds a target power determined for a power supply voltage level;

(x) interpolating the output value of the average power level and gain control block and loading this interpolated output value, after adjustment by a reverse mapper, into the power supply level adjustment generator;

(xi) adjusting the transmission power level to a value slightly below the target power; and

,

(xii) increasing the value of the transmission power level and repeating steps (viii) to (xi) until a maximum specified transmission power point is reached.