Texas Instruments Incorporated
CLOCK DATA RECOVERY

Abstract:

A circuit includes a voltage-controlled oscillator (VCO) and a frequency divider. The frequency divider input is coupled to the VCO output. The circuit further includes a phase-frequency detector (PFD). A control output of the PFD is coupled to the VCO. A first PFD input is coupled to a first frequency divider output, and a second PFD input is coupled to a second frequency divider output. The first frequency divider output is configured to provide a first frequency divider signal and the second frequency divider output is configured to provide a second frequency divider signal 90 degrees out of phase with respect to the first frequency divider signal. The PFD is configured to detect an occurrence of at least two edges of a signal on the data input while the second frequency divider signal is continuously logic high across the at least two edges.