Phase noise suppression

1. A system comprising:

local oscillator circuitry operable to generate a local oscillator signal;

phase noise determination circuitry operable to introduce a frequency-dependent phase shift to said local oscillator signal to generate a phase-shifted version of said local oscillator signal;

mixing circuitry operable to mix said local oscillator signal and said phase-shifted version of said local oscillator to generate a baseband signal having an amplitude proportional to a phase difference between said local oscillator signal and said phase-shifted version of said local oscillator signal; and

digital signal processing circuitry operable to:

process said baseband signal to determine a phase error of said local oscillator signal; and

perform signal compensation based on said determined phase error.

2. The system of claim 1 , wherein said phase noise determination circuitry comprises a phase discriminator cascaded with a limiting amplifier.

3. The system of claim 1 , wherein said phase noise determination circuitry comprises a multi-stage phase discriminator.

4. The system of claim 1 , comprising one or more limiting amplifiers operable to restore levels of said local oscillator signal and said phase-shifted version of said local oscillator signal prior to said mixing of said local oscillator signal and said phase-shifted version of said oscillator signal.

5. The system of claim 1 , wherein said digital signal processing circuitry is operable to remove said frequency-dependent phase shift from said baseband signal to determine said phase error of said local oscillator signal.

6. The system of claim 1 , wherein said signal compensation comprises removal of phase error from a received signal downconverted using said local oscillator signal.

7. The system of claim 1 , wherein said signal compensation comprises compensation of a signal to be upconverted using said local oscillator signal.

8. The system of claim 1 , comprising direct current (DC) suppression circuitry operable to suppress a DC component of said baseband signal.

9. The system of claim 2 , wherein said phase discriminator comprises a capacitive inductive tank circuit.

10. The system of claim 3 , wherein each stage of said multi-stage phase discriminator comprises a phase discriminator and a limiting amplifier.

11. A method comprising:

generating, by local oscillator circuitry, a local oscillator signal;

introducing, by phase noise determination circuitry, a frequency-dependent phase shift to said local oscillator signal to generate a phase-shifted version of said local oscillator signal;

mixing, by mixing circuitry, said local oscillator signal and said phase-shifted version of said local oscillator to generate a baseband signal having an amplitude proportional to a phase difference between said local oscillator signal and said phase-shifted version of said local oscillator signal;

processing, by digital signal processing circuitry, said baseband signal to determine a phase error of said local oscillator signal; and

performing, by said digital signal processing circuitry, signal compensation based on said determined phase error.

12. The method of claim 11 , comprising restoring, by one or more limiting amplifiers, levels of said local oscillator signal and said phase-shifted version of said local oscillator signal prior to said mixing said local oscillator signal and said phase-shifted version of said oscillator signal.

13. The method of claim 11 , comprising removing, by said digital signal processing circuitry, said frequency-dependent phase shift from said baseband signal to determine said phase error of said local oscillator signal.

14. The method of claim 11 , comprising:

downconverting a received signal using said local oscillator signal; and

removing phase error from said downconverted received signal based on said determined phase error.

15. The method of claim 11 , comprising:

compensating a signal to be transmitted based on said determined phase error; and

upconverting said compensated signal to be transmitted using said local oscillator signal.

16. The method of claim 11 , comprising generating, by said digital signal processing circuitry, a direct current (DC) suppression signal for suppressing a DC component of said baseband signal.

17. A system comprising:

local oscillator circuitry operable to generate a local oscillator signal having phase error;

analog circuitry, including one or more phase discriminators and a mixer, operable to generate a signal representative of said phase error; and

digital circuitry operable to perform signal compensation based on said signal representative of said phase error.

18. The system of claim 17 , wherein said analog circuitry is operable to introduce, via said one or more phase discriminators, a frequency-dependent phase shift to said local oscillator signal to generate a phase-shifted local oscillator signal.

19. The system of claim 17 , wherein said digital circuitry is operable to compensate said signal representative of said phase error based on said frequency-dependent phase shift.

20. The system of claim 18 , wherein said analog circuitry is operable to mix, via said mixer, said local oscillator signal and said phase-shifted version of said local oscillator signal.