Bang-bang phase detectors

Multiphase generator apparatus for generating a plurality of clock signal phases from a reference clock signal, the apparatus comprising

• a delay line for receiving said reference clock signal, the delay line comprising a series of tunable delay stages for producing respective said clock signal phases,
• a bang-bang phase detector for receiving two of said clock signal phases as respective detector input signals, the detector being configured to produce a detector output signal whose state distinguishes positive and negative phase differences between said input signals, and
• control logic for receiving said detector output signal and generating a control code for tuning said delay stages in dependence on the detector output signal,
• wherein the bang-bang phase detector comprises:
• a set-reset latch circuit having set and reset inputs for receiving respective said input signals and a latch output for providing a latch output signal whose state varies in dependence on phases of the input signals;
• a pulse generator circuit configured to generate sampling pulses at timings dependent on phase of one of the input signals;
• a data flip-flop circuit having a data input, a clock input connected to the pulse generator circuit for receiving said sampling pulses, and an output for providing said detector output signal;
• and
• a pulse-width extension circuit, connected between said latch output and said data input, configured to extend the width of pulses of a predetermined polarity in the latch output signal to extend the range of input signal phase differences over which the detector output signal correctly distinguishes said positive and negative phase differences.