System and method for power amplifier control in a millimeter wave communication system

1. A system for power amplifier control, comprising:

a processor;

a memory in communication with the processor, wherein the processor and the memory are configured to:

simultaneously provide input signal strength of each of a plurality of power amplifiers in a millimeter wave (mmW) phased array system;

determine an average input signal strength of the plurality of power amplifiers based on the provided input signal strengths using an analog-to-digital converter (ADC);

determine a voltage headroom for the plurality of power amplifiers based on the determined average input signal strength;

estimate a power backoff value based on the voltage headroom; and

determine a gain control value based on the estimated power backoff value.

2. The system of claim 1 , wherein the processor and memory are further configured to develop a digital word representing the average input signal strength of the plurality of power amplifiers.

3. The system of claim 1 , wherein the processor and memory are further configured to determine the voltage headroom (DISTANCE) for the plurality of power amplifiers based on a threshold input signal strength for the plurality of power amplifiers, a calibrated variation for the plurality of power amplifiers, and the determined average input signal strength.

4. The system of claim 3 , wherein the estimated power backoff value is determined using the threshold input signal strength and the voltage headroom.

5. The system of claim 3 , wherein the calibrated variation is based on a calibrated maximum input power and a calibrated average input power.

6. The system of claim 3 , wherein the voltage headroom (DISTANCE) and the threshold input signal strength vary with temperature.

7. The system of claim 1 , wherein the processor and the memory are configured to use the estimated power backoff value to determine an automatic gain control (AGC) signal for a variable gain amplifier coupled to the plurality of power amplifiers.

8. A method for power control, comprising:

simultaneously providing input signal strength of each of a plurality of power amplifiers in a millimeter wave (mmW) phased array system;

determining an average input signal strength of the plurality of power amplifiers based on the provided input signal strengths;

determining a voltage headroom based on the determined average input signal strength;

estimating a power backoff value based on the determined voltage headroom; and

determining a gain control value to achieve the estimated power backoff value.

9. The method of claim 8 , further comprising generating a digital word representing the average input signal strength of the plurality of power amplifiers.

10. The method of claim 8 , further comprising determining the voltage headroom (DISTANCE) for the plurality of power amplifiers based on a threshold input signal strength for the plurality of power amplifiers, a calibrated variation for the plurality of power amplifiers, and the determined average input signal strength.

11. The method of claim 10 , further comprising determining the estimated power backoff value using the threshold input signal strength, and the voltage headroom.

12. The method of claim 10 , wherein the calibrated variation is based on a calibrated maximum input power and a calibrated average input power.

13. The method of claim 10 , wherein the voltage headroom (DISTANCE) and the threshold input signal strength vary with temperature.

14. The method of claim 8 , further comprising using the estimated power backoff value to determine an automatic gain control (AGC) signal for a variable gain amplifier coupled to the plurality of power amplifiers.

15. A device, comprising:

means for simultaneously providing input signal strength of each of a plurality of power amplifiers in a millimeter wave (mmW) phased array system;

means for determining an average input signal strength of the plurality of power amplifiers based on the provided input signal strengths;

means for determining a voltage headroom based on the determined average input signal strength;

means for estimating a power backoff value based on the determined voltage headroom; and

means for determining a gain control value to achieve the estimated power backoff value.

16. The device of claim 15 , further comprising means for generating a digital word representing the average input signal strength of the plurality of power amplifiers.

17. The device of claim 15 , further comprising means for determining the voltage headroom (DISTANCE) for the plurality of power amplifiers based on a threshold input signal strength for the plurality of power amplifiers, a calibrated variation for the plurality of power amplifiers, and the determined average input signal strength.

18. The device of claim 17 , further comprising means for determining the estimated power backoff value using the threshold input signal strength, and the voltage headroom.

19. The device of claim 17 , wherein the calibrated variation is based on a calibrated maximum input power and a calibrated average input power.

20. The device of claim 17 , wherein the voltage headroom (DISTANCE) and the threshold input signal strength vary with temperature.

21. The device of claim 15 , further comprising means for using the estimated power backoff value to determine an automatic gain control (AGC) signal for a variable gain amplifier coupled to the plurality of power amplifiers.

22. A power control system for a millimeter wave (mmW) communication system, comprising:

a plurality of transmission paths, each transmission path having a power amplifier, and an input power detector;

an analog-to-digital converter (ADC) coupled to each input power detector, the ADC configured to generate a single digital value for a plurality of input voltage signals corresponding to an input voltage of each power amplifier within a symbol;

a variable gain amplifier (VGA) coupled to the plurality of transmission paths; and

a processor configured to cause a control signal to be applied to the variable gain amplifier (VGA) responsive to the single digital value.

23. The power control system for a millimeter wave (mmW) communication system of claim 22 , wherein the single digital value generated by the ADC represents an average input signal strength of the power amplifiers.

24. The power control system for a millimeter wave (mmW) communication system of claim 22 , wherein the processor is configured to calculate a voltage headroom (DISTANCE) based on a threshold input signal strength, a calibrated variation, and a determined average power represented by the single digital value.

25. The power control system for a millimeter wave (mmW) communication system of claim 24 , wherein the processor is configured to determine an estimated power backoff value using the threshold input signal strength and the voltage headroom.

26. The power control system for a millimeter wave (mmW) communication system of claim 25 , wherein the estimated power backoff value is used to determine the control signal applied to the VGA.

27. The power control system for a millimeter wave (mmW) communication system of claim 24 , wherein the calibrated variation is based on a calibrated maximum input power and a calibrated average input power.

28. The power control system for a millimeter wave (mmW) communication system of claim 24 , wherein the voltage headroom (DISTANCE) and the threshold input signal strength vary with temperature.

29. The power control system for a millimeter wave (mmW) communication system of claim 22 , wherein the plurality of input voltage signals correspond to a first antenna polarization, and wherein the ADC is configured to generate a second digital value for a second plurality of input voltage signals corresponding to a second antenna polarization.