| This thesis presents ways to improve clock-data recovery (cdr) using digital signal processing techniques. The communication system is presented and the different components of jitter are analyzed. Several different cdrs are presented, including the bang-bang cdr. With the increase in data rates in today's circuit board technology the current cdr technology is being outpaced, jitter is becoming more of a problem. Three cdr algorithms are created, presented, and tested versus the bang-bang cdr. The three algorithms all use the concept of edge detection, found in image processing. The first uses the Hilbert transform to locate the transitions of the signal. The second algorithm uses an algorithm developed for the speech processing field, the "Automate de Cucchi". This algorithm finds the location of noise on a noisy speech signal. The Cucchi cdr uses this concept to smooth the data, and then find the exact location of the transitions. The third algorithm uses the Prewitt operator, this operator is used in the image processing field to locate the edges of an image. The Prewitt cdr uses a one dimensional version of the image operator. Again this algorithm finds the exact location of the transitions. The three algorithms are compared to the bang-bang cdr using eye diagrams. Different metrics of the eye diagrams and four data sets are used for the comparison. Three of the four datasets are simulated data, and the fourth is taken of a Fully-Buffered Dual In-Line Memory Module (FBDIMM) link. The three algorithms outperform the bang-bang cdr in every jitter categories, with as much as 65% improvements. |
