G.ABSTRACTPhase-locked loop coefficient generator for a filter arrange-ment having a non-rational ratio between input and outputsampling frequencies.In a sample rate converter having a non-rationalconversion factor the input samples coincide with low-rateclock pulses and the output samples coincide with high-rateclock pulses, or inversely. It comprises a filter coeffi-cient generator 3 which, based on the distance (deviation)between a low-rate clock pulse and the immediately precedingor immediately subsequent high-rate clock pulse, con-tinuously supplies a series of filter coefficients. To de-termine the deviation a phase-locked loop (30) is provided,with a phase detector (301) receiving the low-rate clockpulses as well as synthetic low-rate clock pulses andsupplying a discrete-time phase difference signal u(.) whichis applied to a processor circuit (302). This circuit suppliesthe desired deviation d(.) and a reference number N which isapplied to a counter circuit (304), This circuit also re-ceives the high-rate clock pulses and each time after re-ceiving the number of clock pulses corresponding to thereference number it supplies a synthetic low-rate clockpulse. In the processor circuit 302 a filtering operation(3021) is first performed on the discrete-time phase dif-ference signal u(.) so that control signal samples H(.) areobtained. An auxiliary sample s(.) is subtracted from such acontrol signal sample and the difference is divided by aweighting factor incr. of the number P thus obtained thosebits whose significance is less than 2° represent thedeviation d(.), while the other bits represent the referencenumber N. By subsequently multiplying the deviation d(.) bythe weighting factor incr, a new auxiliary sample s(. + 1) isobtained (Fig. 1).
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