A 200-Mbps 2-Gbps Continuous-Rate Clock-and-Data-Recovery Circuit
With the aid of wave-length division multiplexing technique, several optical communication systems, such as SDH/SONET and 10 GBased Ethernet, allow the information to be exchanged with different bit rates at the same time in the optical domain. The retiming circuits have to detect the bit rate from the incoming data and the harmonic locking must be prevented. To receive the data with different bit rates over a wide range without the harmonic-locking issue, two kinds of Clock-and-Data-Recovery (CDR) circuits existed in literature. One is the multirate CDR circuit, and the other is the continuous-rate CDR circuit.