Frequency generator with digital adjustment

摘要

A frequency generator contains a PLL oscillator and a microcomputer which acts as a frequency divider preceding an input of a phase meter of the control loop between its clock input and a pulse output. The microcomputer can be clocked either by the oscillator output signal or by a standard frequency source and arranges the duration of an internal programme sequence in dependence on the frequency information just input to it, in such a manner that it corresponds to the period of the reference frequency of the phase meter required for the desired output frequency of the oscillator. In addition, the microcomputer controls a digital/analog converter, the output voltage of which compensates for fluctuations of the phase meter output voltage when a fractional frequency dividing ratio is used. <IMAGE>