A novel FPGA based digital octa-rate clock and data recovery circuit

Abstract

Clock and data recovery (CDR) circuit in general, plays a vital role for serial-link communication in multi-module based System on chip (SOC). It uses a high frequency clock to handle high data rate, which results in high dynamic power consumption. In order to reduce the high dynamic power consumption, the proposed design works at the one-eighth frequency of the received data rate and presents a novel digital octa-rate clock and data recovery circuit as an optimal solution. The octa-rate CDR circuit consists of 16-phases generator, delay line controller, an octa-rate early-late type phase detector and digitally controlled delay line. The purpose of delay line controller is to provide sufficient delay in digitally controlled delay line. It is observed from literature that the existing delay line controller is realized by using combinational circuit which is not providing sufficient delay. Hence, in this work we introduced Finite State Machine (FSM) based delay line controller to provide sufficient delay. In order to reduce dynamic power consumption, a novel octa-rate CDR circuit has been realized using Xilinx ISE 13.2 and implemented on Vertex-5 FPGA target device for real time verification. Corresponding results shows a significant dynamic power reduction.