Multi-stage phase detector

A programmable fabric phase-locked loop (PLL) for high data rate serial digital communications receiving serial data, the phase-locked loop comprising:

• a programmable interface for receiving high data rate serial data;
• a ring oscillator operating as a voltage controlled oscillator that produces four differential clocks;
• a phase detector coupled to receive the four differential clocks and further coupled to receive at least one serial data input stream from the programmable interface wherein the phase detector further includes:
• a sample and hold module further comprising a capacitor configured MOSFET coupled to a gate of an input MOSFET of the sample and hold module wherein the capacitor holds an input value for the gate;
• a logic module for detecting a lack of transition between two data bits produced by the sample and hold module wherein the logic module disables a multiplexer from producing a signal to a transconductance module that produces a biasing signal for the ring oscillator;
• a data buffer for receiving and driving the at least one serial data input stream to produce a buffered serial data stream;
• four buffers coupled to receive the buffered serial data stream for buffering and reducing loading of downstream elements of the phase detector for the data buffer wherein the four buffers provide buffering for four data paths and four phase paths;
• wherein each data path comprises a sample and hold module coupled serially with a dynamic latch that is further coupled serially with the logic module;
• wherein each phase path comprises a pair of sample and hold modules coupled serially and further coupled serially with a multiplexer;
• wherein each multiplexer is coupled to receive a control signal produced by the logic module to cause the multiplexer to not produce an output voltage;
• wherein the phase-locked loop further includes:
• a transconductance module coupled to an output of each multiplexer to receive a voltage therefrom, the transconductance module converting the voltage to a current;
• a loop filter for converting the transconductance module current to a VCO input voltage;
• and
• the ring oscillator producing an oscillation based upon the VCO input voltage.