Phase noise suppression

Abstract

A transceiver comprises local oscillator circuitry, phase noise determination circuitry, mixing circuitry, and digital signal processing circuitry. The local oscillator circuitry is operable to generate a local oscillator signal. The phase noise determination circuitry is operable to introduce a frequency-dependent phase shift to the local oscillator signal to generate a phase-shifted version of the local oscillator signal. The mixing circuitry is operable to mix the local oscillator signal and the phase-shifted version of the local oscillator to generate a baseband signal having an amplitude proportional to a phase difference between the local oscillator signal and the phase-shifted version of the local oscillator signal. The digital signal processing circuity is operable to process the baseband signal to determine a phase error of the local oscillator signal, and perform signal compensation based on the determined phase error.

What is claimed is: 
     
         1 - 20 . (canceled) 
     
     
         21 . A system comprising:
 a local oscillator operable to generate a local oscillator signal;   an amplifier circuit operable to add a phase-shift to the local oscillator signal to generate a phase-shifted local oscillator signal, wherein the phase-shift is frequency-dependent;   a mixer operable to mix the local oscillator signal and the phase-shifted local oscillator signal to generate a baseband signal having an amplitude proportional to a phase difference between the local oscillator signal and the phase-shifted local oscillator signal; and   a digital signal processor (DSP) operable to compensate a received signal based on a phase error of the local oscillator signal, wherein the DSP is operable to determine the phase error of the local oscillator signal according to the baseband signal.   
     
     
         22 . The system of  claim 21 , wherein the amplifier circuit comprises a limiting amplifier. 
     
     
         23 . The system of  claim 21 , wherein the amplifier circuit comprises a phase discriminator. 
     
     
         24 . The system of  claim 21 , wherein the amplifier circuit comprises a multi-stage phase discriminator. 
     
     
         25 . The system of  claim 24 , wherein each stage of the multi-stage phase discriminator comprises a phase discriminator and a limiting amplifier. 
     
     
         26 . The system of  claim 21 , wherein the system comprises one or more limiting amplifiers operable to restore levels of the local oscillator signal and the phase-shifted version of the local oscillator signal prior to the mixing of the local oscillator signal and the phase-shifted version of the oscillator signal. 
     
     
         27 . The system of  claim 21 , wherein the DSP is operable to remove the frequency-dependent phase shift from the baseband signal to determine the phase error of the local oscillator signal. 
     
     
         28 . The system of  claim 21 , wherein the received signal is generated by a downconversion using the local oscillator signal. 
     
     
         29 . The system of  claim 21 , wherein the received signal is upconverted by the local oscillator signal. 
     
     
         30 . The system of  claim 21 , wherein the system comprises direct current (DC) suppression circuit operable to suppress a DC component of the baseband signal. 
     
     
         31 . A method comprising:
 generating, by local oscillator circuitry, a local oscillator signal;   introducing, by an amplifier circuit, a frequency-dependent phase shift to the local oscillator signal to generate a phase-shifted version of the local oscillator signal;   mixing the local oscillator signal and the phase-shifted version of the local oscillator to generate a baseband signal having an amplitude proportional to a phase difference between the local oscillator signal and the phase-shifted version of the local oscillator signal;   processing, by a digital signal processor (DSP), the baseband signal to determine a phase error of the local oscillator signal; and   performing, by the DSP, signal compensation based on the determined phase error.   
     
     
         32 . The method of  claim 31 , wherein the method comprises restoring, by one or more limiting amplifiers, levels of the local oscillator signal and the phase-shifted version of the local oscillator signal prior to the mixing the local oscillator signal and the phase-shifted version of the oscillator signal. 
     
     
         33 . The method of  claim 31 , wherein the method comprises removing, by the DSP, the frequency-dependent phase shift from the baseband signal to determine the phase error of the local oscillator signal. 
     
     
         34 . The method of  claim 31 , comprising:
 downconverting a received signal using the local oscillator signal; and   removing phase error from the downconverted received signal based on the determined phase error.   
     
     
         35 . The method of  claim 31 , comprising:
 compensating a signal to be transmitted based on the determined phase error; and   upconverting the compensated signal to be transmitted using the local oscillator signal.   
     
     
         36 . The method of  claim 31 , comprising generating, by the DSP, a direct current (DC) suppression signal for suppressing a DC component of the baseband signal. 
     
     
         37 . A system comprising:
 a local oscillator operable to generate a local oscillator signal having phase error;   an analog circuit, including one or more phase discriminators and a mixer, operable to generate a signal representative of the phase error; and   a digital signal processor (DSP) operable to perform signal compensation based on the signal representative of the phase error.   
     
     
         38 . The system of  claim 37 , wherein the analog circuit is operable to introduce, via the one or more phase discriminators, a frequency-dependent phase shift to the local oscillator signal to generate a phase-shifted local oscillator signal. 
     
     
         39 . The system of  claim 38 , wherein the analog circuitry is operable to mix, via the mixer, the local oscillator signal and the phase-shifted version of the local oscillator signal. 
     
     
         40 . The system of  claim 37 , wherein the DSP is operable to compensate the signal representative of the phase error based on the frequency-dependent phase shift.