Control of power amplifiers in devices using transmit beamforming

• US 7,899,414 B2
• Filed: 07/21/2009
• Issued: 03/01/2011
• Est. Priority Date: 03/21/2002
• Status: Expired due to Fees

• Current Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Original Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Inventors: Sugar, Gary L., Vaidyanathan, Chandra, Luo, Sifen
• Primary Examiner(s): Le, Thanh C
• Application Number:
  US12/506,813
• Publication Number:
  US 20090285331A1
• Time in Patent Office: 588 Days
• Field of Search: 455/101, 455/103, 455/104, 455/114.1, 455/115.1, 455/127.1, 455/562.1, 375/267, 375/296, 375/297
• US Class Current: 455/103
• CPC Class Codes: H01Q 3/28 varying the amplitude
• 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 3/3089 Control of digital or coded signals
• CPC Class Codes: H04B 1/0483 Transmitters with multiple parallel paths
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04B 7/0857 using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

A radio transmitter and method controls efficiency of each of a plurality of power amplifiers that amplify a corresponding one of a plurality of radio frequency signals for a beamforming transmission by a corresponding one of a plurality of antennas. Each of the plurality of power amplifiers is controlled to operate with one or more operating parameters that optimize the efficiency for an output power level of corresponding ones of the radio frequency signals. Transmit weights for transmit signals are determined and updated on a per-packet basis.

Claims

1. A method for power control of a plurality of power amplifiers used for transmit beamforming, the method comprising:

determining that a packet of information is to be transmitted;

weighting each of a plurality of digital baseband transmit signals with a corresponding one of a plurality of transmit weights to produce a plurality of digital weighted signals representing the packet of information;

converting each of the plurality of digital weighted signals to a corresponding analog signal and then to a corresponding radio frequency signal to produce a plurality of radio frequency signals;

supplying each of the radio frequency signals to a corresponding one of a plurality of power amplifiers that amplify the corresponding radio frequency signal;

supplying each of the radio frequency signals to a corresponding one of a plurality of self-bias boosting circuits associated with corresponding ones of the plurality of power amplifiers, wherein each self-bias boosting circuit biases the corresponding power amplifier according to a level of the corresponding radio frequency signal supplied to it;

amplifying each of the radio frequency signals with a corresponding one of the plurality of power amplifiers for simultaneous transmission; and

updating the transmit weights on a per-packet basis.

2. The method as in claim 1, further comprising:

retrieving the transmit weights from a memory device.

3. A radio transmitter, comprising:

a baseband signal processor configured to determine that a packet of information is to be transmitted, to weight each of a plurality of digital baseband transmit signals with a corresponding one of a plurality of transmit weights to produce a plurality of digital weighted signals representing the packet of information, and to update the transmit weights on a per-packet basis;

a digital to analog converter configured to convert each of the plurality of transmit weights to an analog bias signal;

a plurality of amplifiers, each amplifier configured to amplify an upconverted digital weighted signal as a corresponding radio frequency signal, to produce a plurality of radio frequency signals; and

a plurality of self-bias boosting circuits associated with corresponding ones of the plurality of power amplifiers, wherein each self-bias boosting circuit biases the corresponding power amplifier according to a level of the corresponding radio frequency signal supplied to it;

a plurality of antennas, each antenna corresponding to one of the plurality of amplifiers, configured to simultaneously transmit the plurality of radio frequency signals.

4. The radio transmitter of claim 3, further comprising:

a memory for storing the transmit weights, wherein the baseband processor use a lookup table to derive the analog bias signal from the stored transmit weights.

5. The radio transmitter of claim 3, further comprising:

an upconverter configured to process the digital weighted signals to produce the corresponding radio frequency signal.

6. The radio transmitter of claim 3, wherein the transmit weights are derived based on a channel transfer function between the transmitter and an intended receiving device.