Digital phase calibration method and system
View Patent ↗A method of digital phase calibration is disclosed. An input signal is sampled using a clock. The sample points of the sampled signal are changed by a scaler. A phase calibration is performed by adjusting the phase of the scaler to obtain an optimum phase for the scaler. It is determined whether the input signal represents a static frame and the phase calibration is performed only if the input signal represents a static frame.
1. A method of digital phase calibration, comprising:
sampling an input signal using a sampling clock to generate a sampled signal;
calculating and interpolating samples of the sampled signal by a scaler to generate a scaled signal;
determining whether the scaled signal represents a static display; and
performing phase calibration only when the scaled signal represents the static display, wherein the phase calibration is performed based on the scaled signal by adjusting the phase of the scaler thereby obtaining an optimum phase for the scaler.
2. The method of digital phase calibration as claimed in claim 1 , wherein performing phase calibration further comprises:
setting a phase offset to 0;
filtering the scaled signal to generate a filtered signal;
calculating a statistical value of the filtered signal;
determining whether the statistical value is greater than a maximum value; and
if the statistical value is greater than the maximum value, setting the statistical value and a currently obtained phase offset as the maximum value and an optimum phase offset respectively.
3. The method of digital phase calibration as claimed in claim 2 , further comprising:
if the statistical value is less than or equal to the maximum value, determining whether the current phase offset is equal to a maximum phase offset;
if the current phase offset is less than the maximum phase offset, adding a predetermined value to the phase offset and repeating statistical value calculation and comparison based on the currently obtained phase offset to update the maximum value and the optimum phase offset;
if the current phase offset is equal to the maximum phase offset, designating the optimum phase offsets as the final phase offset for display adjustment.
4. The method of digital phase calibration as claimed in claim 3 , wherein the scaler interpolates samples of the sampled signal to generate the scaled signal using the optimum phase derived from an initial phase and the final phase offset.
5. The method of digital phase calibration as claimed in claim 4 , further comprising generating an initial phase based on a synchronization signal and an interpolation ratio.
6. The method of digital phase calibration as claimed in claim 2 , wherein the statistical value is calculated by summing the absolute value or square value of the filtered signal.
7. The method of digital phase calibration as claimed in claim 1 , further comprising altering the phase of the scaler by a programmable phase offset.
8. A system of digital phase calibration, comprising:
a scaler, interpolating samples of a sampled signal to generate a scaled signal;
a filter, coupled to the scaler, filtering the scaled signal to generate a filtered signal;
a statistical value calculator, coupled to the filter, calculating a statistical value of the filtered signal; and
a phase controller, coupled to the calculator and the scaler, performing phase calibration only when the statistical value represents a static display, wherein the phase calibration is performed by adjusting the phase of the scaler based on the statistical value.
9. The system of digital phase calibration as claimed in claim 8 , wherein the phase controller initially sets a phase offset to 0, determines whether the statistical value is greater than a maximum value, if so, sets the statistical value and a currently obtained phase offset as the maximum value and an optimum phase offset respectively.
10. The system of digital phase calibration as claimed in claim 9 , wherein the phase controller determines whether the current phase offset is equal to a maximum phase offset if the absolute value is less than or equal to the maximum value, adds a predetermined value to the phase offset and repeating statistical value calculation and comparison based on the currently obtained phase offset if the current phase offset is less than the maximum phase offset, and designates the optimum phase offsets as the final phase offset for display adjustment if the current phase offset is equal to the maximum phase offset.
11. The system of digital phase calibration as claimed in claim 10 , wherein the scaler interpolates samples of the sampled signal to generate the scaled signal using the optimum phase derived from an initial phase and the final phase offset.
12. The system of digital phase calibration as claimed in claim 11 , wherein the phase controller further generates an initial phase based on a synchronization signal and an interpolation ratio.
13. The system of digital phase calibration as claimed in claim 8 , wherein the statistical value calculator calculates the statistical value by summing the absolute value or square value of the filtered signal.
14. The system of digital phase calibration as claimed in claim 8 , wherein the filter is a high pass filter.