Transmission antenna array system with predistortion

• US 6,697,436 B1
• Filed: 06/19/2000
• Issued: 02/24/2004
• Est. Priority Date: 07/13/1999
• Status: Expired due to Term

• Current Assignee: Maxlinear Asia Singapore Pte Ltd. (Maxlinear Incorporated)
• Original Assignee: PMC-Sierra Incorporated (Microchip Technology Incorporated)
• Inventors: Bennett, Steven J., Hung, Chun Yeung Kevin, Wright, Andrew S., Klijsen, Bartholomeus T. W., Yee, Paul V.
• Primary Examiner(s): Ghayour, Mohammad H.
• Assistant Examiner(s): GHULAMALI, QUTBUDDIN
• Application Number:
  US09/596,410
• Time in Patent Office: 1,345 Days
• Field of Search: 375/296, 375/297, 330/106, 330/107, 455/126, 455/108
• US Class Current: 375/296
• CPC Class Codes: G01N 27/4163 checking the operation of, or calibrating, the measuring apparatus G01N27/3274, G01N27/4175 and G01N33/0006 take precedence
• CPC Class Codes: G01N 27/44 using electrolysis to generate a reagent, e.g. for titration
• CPC Class Codes: H03F 1/3241 using predistortion circuits H03F1/3211, H03F1/3217 take precedence
• CPC Class Codes: H03F 1/3294 Acting on the real and imaginary components of the input signal
• CPC Class Codes: H03F 2201/3233 Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion

Abstract

A predistortion system adaptively compensates for distortion introduced along one or more amplification chains of a power amplifier system. In one embodiment, the predistortion system includes a plurality of compensation circuits, each of which is coupled to, and configured to digitally predistort an input transmission signal to, a respective amplification chain of an antenna array system. Each such amplification chain has an output coupled to a respective antenna of the antenna array system. A processing unit monitors the input transmission signals to, and corresponding output signals from, each of the amplification chains on a time-shared basis, and generates updates to the compensation parameters used the corresponding compensation circuits.

Claims

1. A transmission antenna array system comprising:

a plurality of amplification chains, each amplification chain having an output coupled to a respective antenna of the array;

a plurality of compensation circuits, each compensation circuit coupled to, and configured to digitally predistort an input transmission signal to, a respective amplification chain using a dynamically updated set of compensation parameters; and

a processing unit that monitors the input transmission signals to, and corresponding output signals from, each of the plurality amplification chains, and processes said input transmission and output signals to adaptively generate updates to the compensation parameters used by each of the plurality of compensation circuits.

2. The transmission antenna array system as in claim 1, wherein the processing unit comprises a single general purpose microprocessor that executes a program to generate the compensation parameter updates for the plurality of compensation circuits.

3. The transmission antenna array system as in claim 1, wherein the processing unit comprises a single digital signal processor that executes a program to generate the compensation parameter updates for the plurality of compensation circuits.

4. The transmission antenna array system as in claim 1, wherein each amplification chain includes a coupler that generates a respective radio frequency (RF) observation signal, and the system further comprises:

a multiplexer that selects between the RF observation signals; and

a circuit for RF downconverting and converting to digital form an RF observation signal selected by the RF multiplexer, to thereby generate digital observation signals for use by the processing unit.

5. The transmission antenna array system as in claim 4, further comprising an input signal multiplexer that selects between the input transmission signals to provide a selected input transmission signal to the processing unit.

6. The transmission antenna array system as in claim 1, wherein each compensation circuit comprises a digital filter from which compensation parameters are read from a respective multi-dimensional data structure, wherein compensation parameters are indexed within and read from each data structure according to a least two different input transmission signal characteristics.

7. The transmission antenna array system as in claim 6, wherein each multi-dimensional data structure has a first dimension that corresponds to an instantaneous signal amplitude or instantaneous power, and has a second dimension that corresponds to an integrated signal envelope.

8. The transmission antenna array system as in claim 6, wherein the compensation circuits comprise finite impulse response predistortion filters for which sets of filter coefficients are read from the multidimensional data structures.

9. The transmission antenna array system as in claim 1, wherein each of the plurality of amplification chains includes a respective radio frequency (RF) upconversion circuit.

10. The transmission antenna array system as in claim 1, wherein the plurality of amplification chains provide for independent power amplification of each signal fed to each respective antenna.

11. In a transmission antenna array system comprising a plurality of amplification chains, a method of predistorting input transmission signals to the amplification chains, comprising;

providing a plurality of compensation circuits, each compensation circuit coupled to, and configured to digitally predistort an input transmission signal to, a respective amplification chain using a dynamically updated set of compensation parameters, wherein each amplification chain has an output that is coupled to a respective antenna of the antenna array system; and

with a single processing module used on a time-shared basis, monitoring the input transmission signals to, and corresponding output signals from, each of the plurality amplification chains, and processing said input transmission and output signals to adaptively generate updates to the compensation parameters used by each of the plurality of compensation circuits.

12. The method as in claim 11, wherein the processing module comprises a single general purpose microprocessor that executes a program to generate the compensation parameter updates for the plurality of compensation circuits.

13. The method as in claim 11, wherein the processing module comprises a single digital signal processor that executes a program to generate the compensation parameter updates for the plurality of compensation circuits.

14. The method as in claim 11, wherein each amplification chain includes a coupler that generates a respective radio frequency (RF) observation signal, and the method further comprises:

selecting between the RF observation signals with an RF multiplexer; and

downconverting, and converting to digital form, the RF observation signal selected by the RF multiplexer, to generate a digital observation signal for use by the processing module.

15. The method as in claim 14, further comprising selecting between the input transmission signals to provide a selected input transmission signal to the processing unit.

16. The method as in claim 11, further comprising storing the compensation parameters generated by the processing module in respective multidimensional data structures of the compensation circuits such that parameter sets are indexed within each data structure according to at least two different input transmission signal characteristics.

17. The method as in claim 16, wherein said input transmission signal characteristics include (a) an instantaneous signal amplitude or instantaneous power, and (b) integrated signal envelope.

18. The method as in claim 11, wherein the compensation parameters include sets of filter coefficients for use within finite impulse response predistortion filters of the compensation circuits.

19. The method as in claim 11, wherein the input transmission signals are wideband signals.

20. The method as in claim 11, further comprising upconverting a respective predistorted input transmission signal to radio frequency (RF) along each of the amplification chains.