Method for reducing jitter in receivers
View Patent ↗A receiver equalizer that provides improved jitter tolerance relative to common adaptation mechanisms and that also provides inter-symbol interference. Improved jitter tolerance is an important benefit for SERDES receivers as tolerance to Sinusoidal Jitter is an important performance metric specified in most industry standards.
1. A method of controlling a receiver equalizer, the receiver equalizer being an analog finite impulse response equalizer (FIR EQ), the method comprising:
receiving an analog signal having a baud rate, the analog signal being an equalized analog signal output from the analog FIR EQ;
sampling the analog signal at a sampling rate of twice that of the baud rate, the sampling to obtain a sampled signal that includes two interleaved digital signals, a first signal of the two interleaved digital signals being a data signal, the data signal comprising data samples sampled at a center of each consecutive symbol of the analog signal, a second of the two interleaved digital signal being a timing signal, the timing signal comprising timing samples sampled between the consecutive symbols;
sampling the analog signal at a frequency equal to the baud rate to obtain utility upper samples and utility lower samples that are coincident, in time, with the timing samples of the timing signal;
calculating a timing error term for timing samples comprised between data samples that define non-zero crossing transitions, the calculating of the timing error term including calculating the timing error term as a function of timing, utility upper, and utility lower samples that are coincident in time; and
controlling the receiver equalizer as a function of the timing error term.
2. A receiver comprising:
a sampling means for sampling an analog signal having a baud rate, the sampling means to sample the analog signal at a sampling rate of twice that of the baud rate, the sampling to obtain a sampled signal that includes two interleaved digital signals, a first signal of the two interleaved digital signals being a data signal, the data signal comprising data samples sampled at a center of each consecutive symbol of the analog signal, a second of the two interleaved digital signal being a timing signal, the timing signal comprising timing samples sampled between the consecutive symbols;
processing means operationally connected to the sampling means, the processing means to calculate a timing error term of timing samples comprised between data samples that define non-zero crossing transitions;
an equalizer to equalize one of the sampled signal and the analog signal, the equalizer being an analog finite impulse response filter (FIR EQ), the analog signal being an equalized signal output from the analog FIR EQ;
an additional sampling means to sample the analog signal at a frequency equal to the baud rate to obtain utility upper samples and utility lower samples that are coincident, in time, with the timing samples of the timing signal, the processing means calculating the timing error term as a function of timing, utility upper, and utility lower samples that are coincident in time; and
a control module operationally connected to the processing means and to the equalizer, the control module to control the equalizer as a function of the timing error term.
3. The receiver of claim 2 wherein the sampling means is a 1-bit slicer.
4. The receiver of claim 2 wherein the additional sampling means includes at least one 1-bit slicer.