A 360° Digital Phase Detector with 100-kHz Bandwidth

The general availability of digital circuit components with propagation delay times of a few nanoseconds makes a digital phase detector with good bandwidth feasible. Such a circuit has a distinct advantage over its analog counterpart because of its linearity over a wide range of phase shift. This paper describes a phase detector that is being built at Los Alamos National Laboratory for the Fusion Materials Irradiation Test (FMIT) project. The specifications are 100-kHz bandwidth, linearity of ± 1° over ± 180° of phase shift, and 0.66° resolution. To date, the circuit has achieved the bandwidth and resolution. The linearity is approximately ± 3° over ± 180° phase shift.