Phase-locked loop type frequency synthesizer having improved loop response

Abstract From the Canadian patent

A frequency synthesizer using a phase-locked loop is disclosed. The frequency synthesis is accomplished by a closed loop arrangement which includes a digital phase detector, a fixed frequency divider with a divide value Nvd a direct digital synthesizer, a loop filter (low-pass filter) and a voltage controlled oscillator. The direct digital synthesizer (DDS) produces a signal whose frequency is defined by a first presetfrequency (FdO) and a second preset frequency (.delta.Fd) multiplied by a suitable variable coefficient (m). The output frequency of the frequency synthesizer is determined by (Nvd FdO + Nvd .delta.Fd m).