Digitally controlled oscillator

Abstract

A digitally controlled oscillator is provided with a memory, storing the half periods T.sub.i (i=1, 2, ..., n) of corresponding frequencies f.sub.i =1/(2T.sub.i) to be generated, and with a digital feedback circuit, in which circuit the half periods taken from memory are decreased by a fixed time value .tau. on a time sharing basis, and in which circuit, as soon as the residual values .DELTA..sub.i,1 =T.sub.i -k.sub.i,1 .tau.<.tau. are obtained, these residual values are increased by the corresponding half periods T.sub.i also on a time sharing basis, and each value so increased is repeatedly decreased by the fixed time .tau.. On repeating this process j times, the residual values can be expressed by: .DELTA..sub.i,j =T.sub.i +.DELTA..sub.i,j-1 -k.sub.i,j .tau., where each k.sub.i,j is so large that 0.ltoreq..DELTA..sub.i,j <.tau.. The digital feedback circuit is connected to n residual value counters, which are each supplied with a series of residual values .DELTA..sub.i,j and which, on reaching a fixed value, bring about that a circuit connected to the respective counter produces a square-wave signal of frequency f.sub.i.