PROBLEM TO BE SOLVED: To allow a pulse phase difference coding circuit, which is used for coding and detecting a phase difference of two pulses, to extend a detection range without making the circuit large in scale extension and detection accuracy deterioration. ;SOLUTION: A pulse PA is given to a rind delay signal generating circuit 1 consisting of plural inverters connected in annular form and is circulated in the circuit 1. A pulse selector 3 and an encoder 4 detect a circulating position of the pulse PA in the ring delay signal generating circuit 1, when they receive a pulse PB. Furthermore, plural counters 21, 22 count the number of times of circulation of the pulse PA at different positions in a ring delay signal generating circuit 1 from the time when the pulse PA is received till the time when the pulse PB is received. A multiplexer 27 selects either of the outputs of the counters 21 or 22 according to the pulse PA to decide the number of times of circulation, and outputs a signal representing a phase difference between the pulse PA and the pulse PB, based on the decided circulation number of times and the circulating position.;COPYRIGHT: (C)1999,JPO
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