Signal imbalance detection systems and methods
In a communication device and corresponding methods to determine a phase offset imbalance, an input signal (e.g. oscillator signal) is phase shifted to generate a set of phase-shifted values. The set of phased-shifted values and the input signal are mixed to generate a respective set of mixed signals. The phase offset imbalance (e.g. phase error) is calculated based on the set of mixed signals and a gradient value.
1. A phase error detection method, comprising:
phase shifting an input signal to generate a set of phase-shifted values;
mixing the set of phased-shifted values and the input signal to generate a respective set of mixed signals;
cross correlating the set of mixed signals to determine a cross correlation signal; and
calculating a phase error based on the cross correlation signal and a gradient value associated with the cross correlation signal.
2. The method of claim 1 , wherein phase shifting the input signal comprises phase shifting the input signal by multiples of a phase shift value to generate the set of phase-shifted signals.
3. The method of claim 1 , wherein mixing the set of phased-shifted signals and the input signal comprises multiplying each phase-shifted value of the set of phase-shifted values by the input signal to generate respective mixed signal values that form the set of mixed signals set of mixed signals.
4. The method of claim 1 , wherein the mixing comprises down converting the set of phase-shifted values by the input signal.
5. The method of claim 1 , wherein the gradient value is a slope of the cross correlation signal.
6. The method of claim 1 , wherein the mixing comprises:
performing a triangular function on the input signal to generate a triangular value; and
cross correlating the triangular value to generate the cross correlation signal.
7. The method of claim 1 , wherein the input signal is a quadrature modulated signal having an in-phase (I) component and an in-quadrature (Q) component, the set of mixed signals corresponding to a triangular function of the I component and a triangular function of the Q component.
8. The method of claim 1 , wherein the input signal is a quadrature modulated signal having an in-phase (I) component and an in-quadrature (Q) component.
9. A non-transitory computer-readable storage medium with an executable program stored thereon, when executed, causes a processor to perform the method of claim 1 .
10. The method of claim 1 , wherein the mixed signals of the set of mixed signals are triangle-wave signals.
11. The method of claim 1 , wherein the set of mixed signals correspond to a triangular function of the input signal.
12. The method of claim 1 , wherein the set of phased-shifted values and the input signal are square-wave signals, the mixing of the set of phased-shifted values and the input signal generates the respective set of mixed signals as triangle-wave signals.
13. The method of claim 1 , wherein the calculated phase error is a function of the cross correlation signal and the gradient value.
14. The method of claim 13 , wherein the gradient value is a slope of the cross correlation signal.
15. The method of claim 1 , wherein calculating the phase error comprises dividing the cross correlation signal by the gradient value.
16. The method of claim 15 , wherein the gradient value is a slope of the cross correlation signal.
17. A demodulator comprising:
a phase shifter configured to phase shift an input signal to generate a set of phase-shifted values;
a mixer configured to mix the set of phased-shifted values and the input signal to generate a respective set of mixed signals; and
an imbalance calculator configured to:
cross correlate the set of mixed signals to determine a cross correlation signal; and
calculate a phase error based on the cross correlation signal and a gradient value associated with the cross correlation signal.
18. The demodulator of claim 17 , wherein phase shifter is configured to phase shift the input signal by multiples of a phase shift value to generate the set of phase-shifted signals.
19. The demodulator of claim 17 , wherein the mixer is configured to multiply each phase-shifted value of the set of phase-shifted values by the input signal to generate respective mixed signal values that form the set of mixed signals set of mixed signals.
20. The demodulator of claim 17 , wherein the mixing comprises down converting the set of phase-shifted values by the input signal.
21. The demodulator of claim 17 , wherein the gradient value is a slope of the cross correlation signal.
22. The demodulator of claim 17 , wherein the input signal is a quadrature modulated signal having an in-phase (I) component and an in-quadrature (Q) component, the set of the mixed signals corresponding a triangular function of the I component and a triangular function of the Q component to generate the triangular value.
23. The demodulator of claim 17 , wherein the input signal is a quadrature modulated signal having an in-phase (I) component and an in-quadrature (Q) component.
24. A wireless communication device comprising the demodulator of claim 17 .