A Multi-gigabit CMOS Transceiver with 2x Oversampling Linear Phase Detection
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Date
2003-05-25
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Abstract
This dissertation presents the design of a high-speed CMOS transceiver for serial digital data. The design is based on a parallel architecture data recovery circuit. It uses multiple clock phases from a multi-phase phase-locked loop (MPLL) operating at low frequency to sample high frequency input data in a time-interleaved manner. This results in the reduction of the speed requirement for the transceiver. The new technique of time-interleaved sampling is realized by placing the analog and digital samplers alternately to sample the input data at a sampling rate of two times the data rate (2x). This hybrid parallel sampling scheme provides the input phase error to the multi-phase PLL and simultaneously recovers and deserializes the input data. The data phase detection generates the loop error signal that is proportional to the input phase error, therefore allowing the PLL to have a proportional loop control. This results in improvement of the loop stability, the output jitter, and the bit error rate over the conventional all-digital 2x oversampling, referred to as the bang-bang type phase detection. In addition, to investigate its operation closely, the model and analysis of the multi-phase PLL based on the discrete-time linear system has been developed. This model takes into account the sampling nature of the loop, which provides greater insight into the system behavior and an understanding of system constraints. The analysis shows that when the PLL loop bandwidth is much smaller than the input frequency, the system response can be approximated by the conventional continuous-time model and thus the number of phase detectors employed can be reduced. The model predicts the stability limit of the multi-phase PLL as a function of input frequency, loop bandwidth, and the number of phase detectors. In addition, the phase noise due to the bang-bang type phase detector in PLL-based clock recovery circuits has been analyzed using this model.
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Phase-locked Loop, Clock and Data Recovery Circuit
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Degree
PhD
Discipline
Electrical Engineering
