Minimizing non-deterministic noise by using wavelet transform
A wavelet transform noise minimization circuit comprises a differential receiver, a voltage comparator, a wavelet transform circuit, an electrical idle (EI) detector circuit, a phase interpolator, a phase-locked-loop (PLL), and a reference clock buffer. The wavelet transform noise minimization circuit may be beneficially applied wherever there is non-deterministic (e.g., random) noise in the PHY layer during an electrical idle state. The wavelet transform noise minimization circuit may be used to improve noise margin during an electrical idle state, and/or reduce the occurrence of false activation of a PHY layer when in the electrical idle state.
1. A method for minimizing the effect of non-deterministic noise during an idle condition of a serial data link in an information handling system, said method comprising the steps of:
a) detecting a non-deterministic noise signal of a serial data link;
b) comparing the non-deterministic noise signal to a noise threshold signal, wherein:
b1) if the non-deterministic noise signal is less than the noise threshold signal, then keeping the serial data link in an electrical idle state, and
b2) if the non-deterministic noise signal is greater than or equal to the noise threshold signal, then
b2a) decomposing the non-deterministic noise signal in a time domain,
b2b) decomposing the non-deterministic noise signal in a frequency domain,
b2c) determining a level of adaptive filtration for the time domain decomposed non-deterministic noise signal, and
b2d) determining equalizer tap settings for the frequency domain decomposed non-deterministic noise signal;
c) generating an output signal from the adaptively filtered time domain decomposed non-deterministic noise signal and the tap equalized frequency domain decomposed non-deterministic noise signal;
d) comparing the output signal to the non-deterministic noise signal, wherein:
d1) if the output signal is less than the non-deterministic noise signal, then keeping the serial data link in the electrical idle state, and
d2) if the output signal is greater than or equal to the non-deterministic noise signal, then repeating steps b2a, b2b, b2c, b2d, c, d, d1 and d2;
wherein each of the steps is performed in the information handling system.
2. The method of claim 1 , further comprising the step of coupling the non-deterministic noise signal to a PHY layer of the information handling system when the non-deterministic noise signal is less than the noise threshold signal.
3. The method of claim 1 , further comprising the step of coupling the output signal from the adaptively filtered time domain decomposed non-deterministic noise signal and the tap equalized frequency domain decomposed non-deterministic noise signal to a PHY layer of the information handling system when the non-deterministic noise signal is greater than or equal to the noise threshold signal.
4. The method of claim 1 , wherein the noise threshold signal is less than about 65 millivolts peak-to-peak.
5. The method of claim 1 , wherein the noise threshold signal is less than about 45 millivolts peak-to-peak.
6. An information handing system having a non-deterministic noise minimization circuit for improving noise margin of a serial data link electrical idle state, said system comprising:
an information handling system having a wavelet transform noise minimization circuit coupled to a serial data link, wherein the wavelet transform noise minimization circuit comprises:
a serial data receiver having an output, and an input coupled to the serial data link;
a voltage comparator having a first input coupled to the output of the serial data receiver;
a wavelet transform circuit having an input coupled to the output of the serial data receiver; and
an electrical idle detector circuit having a first input coupled to an output of the wavelet transform circuit, a second input coupled to an output of the voltage comparator, and an output coupled to a second input of the voltage comparator, wherein if a non-deterministic noise signal from the output of the serial data receiver is greater than or equal to a noise threshold signal from the output of the electrical idle detector circuit, then the wavelet transform circuit decomposes the non-deterministic noise signal into time and frequency domains, determines an adaptive filtration level for the time domain decomposed non-deterministic noise signal and equalizer tap settings for the frequency domain decomposed non-deterministic noise signal; and
the wavelet transform circuit generates an adaptively filtered time domain decomposed non-deterministic noise signal and the tap equalized frequency domain decomposed non-deterministic noise signal at its output which is coupled to the first input of the electrical idle detector circuit.
7. The information handing system according to claim 6 , wherein the non-deterministic noise signal is coupled to a PHY layer of the information handling system when the non-deterministic noise signal is less than the noise threshold signal during an electrical idle state.
8. The information handing system according to claim 6 , wherein a second output of the wavelet transform circuit is coupled to a PHY layer of the information handling system when the non-deterministic noise signal is greater than or equal to the noise threshold signal during an electrical idle state.
9. The information handing system according to claim 6 , wherein the output of the wavelet transform circuit comprises an inverted, noise cleaned, filtered and equalized version of the non-deterministic noise signal.
10. The information handing system according to claim 9 , wherein the inverted, noise cleaned, filtered and equalized version of the non-deterministic noise signal is generated by the wavelet transform circuit using an inverse wavelet transform to the time domain.
11. The information handing system according to claim 10 , wherein the wavelet transform circuit decomposes and analyzes the non-deterministic noise signal substantially simultaneously in both the time and frequency domains.
12. The information handing system according to claim 6 , further comprising a clock buffer coupled to a system clock.
13. The information handing system according to claim 12 , further comprising a phase-locked-loop (PLL) coupled to an output of the clock buffer wherein the PLL coherently multiplies a frequency of the system clock.
14. The information handing system according to claim 13 , further comprising a phase interpolator coupled to an output of the PLL, wherein the phase interpolator generates a plurality of phase coherent clock signals.
15. The information handing system according to claim 13 , wherein outputs of the phase interpolator are coupled to the serial data receiver and the electrical idle detector.
16. The information handing system according to claim 6 , wherein the noise threshold signal is less than about 65 millivolts peak-to-peak.
17. The information handing system according to claim 6 , wherein the noise threshold signal is less than about 45 millivolts peak-to-peak.
18. The information handing system according to claim 6 , wherein the serial data receiver input is a differential input.
19. An apparatus for wavelet transform noise minimization, comprising:
a serial data receiver having an output, and an input adapted for coupling to a serial data link;
a voltage comparator having a first input coupled to the output of the serial data receiver;
a wavelet transform circuit having an input coupled to the output of the serial data receiver; and
an electrical idle detector circuit having a first input coupled to an output of the wavelet transform circuit, a second input coupled to an output of the voltage comparator, and an output coupled to a second input of the voltage comparator, wherein if a non-deterministic noise signal from the output of the serial data receiver is greater than or equal to a noise threshold signal from the output of the electrical idle detector circuit, then the wavelet transform circuit decomposes the non-deterministic noise signal into time and frequency domains, determines an adaptive filtration level for the time domain decomposed non-deterministic noise signal and equalizer tap settings for the frequency domain decomposed non-deterministic noise signal; and
the wavelet transform circuit generates an adaptively filtered time domain decomposed non-deterministic noise signal and the tap equalized frequency domain decomposed non-deterministic noise signal at its output which is coupled to the first input of the electrical idle detector circuit.
20. The apparatus according to claim 19 , wherein the output of the wavelet transform circuit comprises an inverted, noise cleaned, filtered and equalized version of the non-deterministic noise signal.
21. The apparatus according to claim 20 , wherein the inverted, noise cleaned, filtered and equalized version of the non-deterministic noise signal is generated by the wavelet transform circuit using an inverse wavelet transform to the time domain.
22. The apparatus according to claim 21 , wherein the wavelet transform circuit decomposes and analyzes the non-deterministic noise signal substantially simultaneously in both the time and frequency domains.
23. The apparatus according to claim 19 , wherein a second output of the wavelet transform circuit is adapted for coupling to a PHY layer of an information handling system when the non-deterministic noise signal is greater than or equal to the noise threshold signal during an electrical idle state.