Incrementally tuned phase locked loop frequency synthesizer

Abstract

A frequency synthesizer with a voltage-controlled oscillator that can be tuned over its total frequency range in increments of a prescribed frequency range a frequency-dictating component. A reference oscillator emits a reference signal of a strictly prescribed frequency that is supplied as a first input signal to a comparator to which is simultaneously supplied a second input signal of a frequency that is a function of the frequency of the output signal from the voltage-controlled oscillator. The comparator generates a fine-tuning signal in accordance with the difference between the frequencies or between the phases of the first and second input signals and supplies the fine-tuning signal to the voltage-controlled oscillator. The second input signal supplied to the comparator is generated by a variable frequency divider that is adjusted by means of a variable electronic setting component to which the fine-tuning signal is supplied and which continues to vary the dividing factor of the frequency divider until the voltage of the fine-tuning signal assumes a defined level within a prescribed range of voltages that fine-tunes the frequency of the output signal from the voltage-controlled oscillator, whereby the frequency of the output signal is within the subsidiary frequency range set at the frequency-dictating component.