Tuned LC Clock Buffers with Static Phase Adjust

An LC tank providing clock buffering for a half-rate binary phase detector in a clock and data recovery circuit is described. This paper analyzes the trade-offs involved in choosing the Q of the LC tank, presents an automatic tuning method for the LC tank and describes a method to program the phase of the clock relative to the input data using 2 LC tanks with mismatched center frequencies. This work is part of a transceiver chip for XFP fiber optic application fabricated in a 0.13μm CMOS process.