High resolution frequency synthesizer with single stage phase control loop having and adjustable phase and amplitude control loop filter

摘要

The frequency synthesizer generates an electronic alternating voltage signal with a frequency selectable within given limits. The device includes a phase regulating loop comprising an oscillator with controllable frequency, a frequency splitter for the oscillator signal, a phase comparator which converts a phase differential into a proportional electrical signal and a loop filter for the output signal of the comparator. The synthesizer, with the aid of the phase regulator loop, stabilizes the output frequency relative to a reference frequency. The comparison signal of the phase regulating loop is generated by means of a variable time delay from the constant frequency taken from the reference frequency. A phase generator generates, from input data, the target phase value of the comparison signal. This target value serves to control the time delay. The phase error calculated from the difference between the target value and the time delay value, is digitized and a delta sigma process is used to generate the comparison signal.