FRACTIONAL N FREQUENCY SYNTHESIZER AND SPURIOUS CANCELLATION CIRCUIT THEREFOR

摘要

PROBLEM TO BE SOLVED: To reduce the area of a spurious cancellation circuit of the fractional N frequency synthesizer and to improve the accuracy of spurious cancellation. ;SOLUTION: This spurious cancellation circuit 7 is composed of a pulse generating circuit 8 that provides an output of a pulse voltage signal Sp having a pulse width proportional to an output value acm of an accumulator from a point of time when a reset signal Reset is received and a constant current circuit 9 that is driven by the pulse voltage signal Sp to provide an output of an output current Isc of the spurious cancellation circuit 7.;COPYRIGHT: (C)1998,JPO