Low-jitter symbol timing recovery for M-ary QAM and PAM signals

This thesis focuses on low-jitter symbol timing recovery schemes applicable to M-ary QAM and PAM signals. Franks and Bubrowski introduced highpass prefiltering and symmetric bandpass post-filtering for jitter-free operation of a symbol timing recovery scheme using a squarer for binary signaling. We show that the same conditions are also applied to M-ary PAM or QAM signals. In this work, we have investigated the effects of imperfections in both prefiltering and post-filtering on the jitter performance using analysis, simulation and experiments. It is shown that, although a zero-jitter cannot be achieved due to the imperfections, a good selection of pre-filtering can significantly reduce the timing jitter of the recovered clock signal. Jitter performance of the squarer with and without prefiltering for M-ary PAM signals is presented. We also demonstrated that a perfect prefiltering of the received baseband signal essentially produces an equivalent double-sided band, suppressed-carrier (DSB-SC) passband signal centered at the Nyquist frequency (i.e., $1\over2$ of the symbol clock frequency). (Abstract shortened by UMI.