Frequency synthesizer with functional division having a low phase jitter, and use of this synthesizer

Abstract

Abstract 1. Frequency synthesizer operating with fractional division and reduced phase jumping, comprising : - a controlled oscillator (11) supplying a signal of the period 1/Fs ; - a first analog adder (15) having an output coupled to a control input of the oscillator (11) ; - a frequency divider (8) of variable order RV, supplying a signal of the frequency Fs /RV ; - means (6) for supplying a reference signal ; - a modulo M counter (7), referred to as a phase accumulator, supplying a binary word C the value, modulo M, of which increases by a value kM at each period of the reference signal, k being comprised between 0 and 1 ; - a device (10) for the digital-analog conversion and correction, coupling a first output of the phase accumulator (7) to a first input of the first adder (15) ; - a phase comparator (9) receiving the signal supplied by the divider (8) and the reference signal, and supplying to a second input of the first adder (15) an analog signal the value of which is proportional to the phase difference between these two signals and proportional to the period 1/Fs ; characterized in that the device (10) for the digital-analog conversion and correction comprises : - a plurality of timing devices (59 to 66), each performng a timing of a duration which is proportional to the value of a determined fraction of the binary word C and proportional to the period 1/Fs ; - a plurality of sources (70 to 78) each supplying an analog signal the value of which is constant and respectively corresponds to the rate of one of the fractions of the binary word C ; - a second analog adder (79) having an output coupled to the first input of the first analog adder (15) ; - a plurality of analog switches (67 to 70) respectively connecting the sources (70 to 78) to the inputs of the second adder (79) and being respectively controlled by the timing devices (59 to 66).

Inventors

• 👤 André Roullet
• 👤 Jacques Molina

Bibliographic Details