Digital dithering for reduction of quantization errors and side-lobe levels in phased array antennas

Patent metadata

Field	Value
Publication number	US-10374663-B2
Application number	US-201615396070-A
Country	US
Kind code	B2
Filing date	Dec 30, 2016
Priority date	Dec 30, 2016
Publication date	Aug 6, 2019
Grant date	Aug 6, 2019

Abstract

Systems and methods disclosed herein provide techniques for reducing quantization errors and side lobe levels in phased array antennas. The states of a quantized phase shifter of a phased array antenna may be dithered to achieve a time-averaged value that reduces quantization errors. By rapidly switching between the different states of the quantized phase shifter, a time-average value close to a desired phase state may be achieved with a low resolution phase shifter.

First claim

What is claimed is:

1. A method, comprising:
receiving an input signal at a quantized phase shifter of a phased array antenna;
obtaining a time averaged, phased shifted signal that reduces a quantization error of the phase shifter, wherein obtaining the time averaged phase shifted signal comprises switching between two phase states of the quantized phase shifter a plurality of times to obtain a time-averaged value of a state of the quantized phase shifter that is between values of the two phase states; and
outputting the time averaged, phase shifted signal to an antenna element circuit of the phased array antenna.

2. The method of claim 1 , wherein switching between the two phase states of the quantized phase shifter comprises switching between the two phase states of the quantized phase shifter at a rate greater than the highest symbol rate of an adjacent satellite.

3. The method of claim 2 , wherein switching between the two phase states of the quantized phase shifter comprises switching between the two phase states of the quantized phase shifter at a rate at least four times greater than the highest symbol rate of an adjacent satellite.

4. The method of claim 1 , wherein the time averaged, phase shifted signal is obtained using at least linear interpolation or accumulator interpolation.

5. The method of claim 1 , wherein obtaining the time averaged, phase shifted signal comprises:
obtaining an error signal by comparing an output phase to a required phase; and
providing the error signal as an input to an integrator to obtain an integrated signal.

6. The method of claim 5 , wherein obtaining the time averaged, phase shifted signal comprises:
unwrapping the output phase of the integrated signal to obtain an unwrapped signal; and
quantizing the unwrapped signal.

7. The method of claim 1 , wherein the quantized phase shifter is 1-bit or 2-bit phase shifter.

8. The method of claim 1 , wherein the quantized phase shifter provides a constant phase shift of an input signal over a frequency.

9. The method of claim 1 , wherein the quantized phase shifter provides a true time delay of an input signal.

10. The method of claim 1 , wherein switching between the two phase states of the quantized phase shifter a plurality of times to obtain a time-averaged value of a state of the quantized phase shifter that is between values of the two phase states, comprises: using pulse width modulation duty cycles corresponding to the two phase states to obtain the time-averaged value.

11. A phased array antenna, comprising:
a plurality of quantized phase shifters;
a controller to switch between the phase states of each of the plurality of quantized phase shifters to obtain a time-averaged, phase shifted signal from each of the plurality of quantized phase shifters, wherein the controller is configured to obtain the time-averaged, phase shifted signal for each of the plurality of quantized phase shifters by switching between two phase states of the quantized phase shifter a plurality of times to obtain a time-averaged value of a state of the quantized phase shifter that is between values of the two phase states; and
a plurality of antenna elements, wherein each of the plurality of antenna elements is to receive the time-averaged, phase shifted signal from a respective one of the plurality of quantized phase shifters.

12. The phased array antenna of claim 11 , wherein each of the plurality of quantized phase shifters is 1-bit or 2-bit phase shifter.

13. The phased array antenna of claim 11 , wherein each of the plurality of quantized phase shifters provides a constant phase shift of an input signal over a frequency.

14. The phased array antenna of claim 11 , wherein each of the plurality of quantized phase shifters provides a true time delay of an input signal.

15. The phased array antenna of claim 11 , wherein the phased array antenna is a phased array antenna of a very small aperture terminal (VSAT).

16. The phased array antenna of claim 11 , wherein the phased array antenna is a phased array antenna of a satellite.

17. The phased array antenna of claim 11 , wherein the controller is to obtain the time-averaged, phase shifted signal of each of the plurality of quantized phase shifters using at least linear interpolation or accumulator interpolation.

18. A method, comprising:
receiving an RF communication signal at each of a plurality of antenna elements of a phased array antenna;
outputting a signal from an antenna element to a quantized phase shifter; and
obtaining a time averaged, phased shifted signal that reduces a quantization error of the phase shifter, wherein obtaining the time averaged phase shifted signal comprises switching between two phase states of the quantized phase shifter a plurality of times to obtain a time-averaged value of a state of the quantized phase shifter that is between values of the two phase states.

19. The method of claim 18 , wherein obtaining the time averaged, phased shifted signal comprises: obtaining an error signal by comparing an output phase to a required phase; and providing the error signal as an input to an integrator to obtain an integrated signal.

20. The method of claim 18 , wherein the time averaged, phase shifted signal is obtained using linear interpolation or accumulator interpolation.

21. The method of claim 18 , further comprising: amplifying the RF communication signal received at each of the plurality of antenna elements using a low noise amplifier.

Assignees

• Hughes Network Systems Llc

Inventors

• Jackson Thomas
• Alsawaha Hamad
• Lu Bingqian
• Hou Peter
• Mao Yilin

Classifications

• H01Q21/22

  Antenna units of the array energised non-uniformly in amplitude or phase, e.g. tapered array or binomial array · CPC title

• H04B7/01 Primary

  Reducing phase shift · CPC title

• H01Q3/38

  the phase-shifters being digital · CPC title

• H01Q3/26

  varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture ({H01Q3/12,} H01Q3/22, H01Q3/24 take precedence) · CPC title

• H04B7/18528 Primary

  Satellite systems for providing two-way communications service to a network of fixed stations, i.e. fixed satellite service or very small aperture terminal [VSAT] system · CPC title