RF phase measurement at PHERMEX using time-to-digital converters

Recent advances in time-to-digital converters (TDCs) have made 50-MHz RF phase measurement possible without the use of double-balanced mixers. These advances allow zero crossing discriminators to be used in conjunction with fast CAMAC TDCs to make amplitude-independent phase measurements. This method uses a time interval proportional to the phase angle, thus eliminating the calculations and calibration required with double-balanced mixers. The detection system is capable of accurate (+or-2 degrees ) measurement of phase angle between signals of unknown amplitude at 50 MHz. It is concluded that, in terms of simplicity, accuracy, cost, and flexibility, the method is superior to the double-balanced mixer approach previously used at the Los Alamos PHERMEX (Pulsed High Energy Radiographic Machine Emitting X-rays) facility.<>