Fast digital phase detection or frequency discrimination using surface acoustic waves
Robert B. Ward · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1990
In the present device, which consists of a SAW sensor and a specialized IC processor, the former generates a set of voltages whose pattern represents the delay or phase difference of the input signals, while the latter produces a parallel digital readout of delays or phases on the bases of voltage comparisons and unclocked logic operations. If equipped with a delay on one input branch, this SAW sensor can measure frequency using the same processor. Six- and seven-bit devices are envisioned with response times of the order of 100 nsec.