GB1496397A - Phase detectors - Google Patents

Abstract

1496397 Phase detectors SIEMENS AG 6 May 1975 [14 May 1974] 19039/75 Heading H3A A phase detector suitable for use in a phase controlled loop and producing first and second pulsed output signals c, d, the pulse widths of which are dependent upon the phase difference between an input binary signal m and a reference binary signal b which is nominally at twice the frequency of m comprises an arrangement including a delay element V, a bi-stable stage F and logic stages G 1 , G 2 which operate in response to preselected combinations of particular binary values of the input binary signal m, the reference signal b and the delayed reference signal b 1 to produce the signals c, d. The difference between the pulse widths of the signals c and d is a measure of the phase difference between the rising flanks of the reference and input signals b, m. The phase detector emits no c, d pulses if a reference pulse is missing over a time interval. The delay element V may be constituted by a transit time element or by a shift register. The logic elements G 1 -G 4 may be constituted by AND, Invert or NAND gates. Fig. 4 (not shown) relates to a detailed circuit arrangement of Fig. 1.