Patent ID: 7928805

Claim:
A broadband frequency synthesizer including in a phase-lock loop: a voltage controlled oscillator for providing at least one high frequency output signal within a determined frequency band, a dual mode divider circuit for dividing the output signal frequency by a first factor N 1 in a first selected mode M 1 or by a second factor N 2 different from the first factor N 1 in a second selected mode M 2 in order to supply a divided frequency signal, a means for selecting a division mode of the divider circuit for selecting by a determined time period a first division mode or a second division mode of the divider circuit in order to define a mean of first division mode M 1 and second division mode M 2 over time as a function of the programmed frequency of the output signal of the voltage controlled oscillator in the frequency band defined by the first and second division factors N 1 and N 2 , a phase detector for comparing a reference frequency signal to the divided frequency signal provided by the divider circuit, and a low-pass filter for filtering the output signal of the phase detector to provide a filtered control signal to the voltage controlled oscillator, wherein when the frequency of the output signal is close to the centre of the frequency band defined by the first and second division factors N 1 and N 2 , the dual mode divider circuit is configured for dividing the output signal frequency by a third factor N 3 in a first selected mode M 1 or by a fourth division factor N 4 different from the third factor N 3 in a second selected mode M 2 according to a programming of the selection means, at least the third division factor N 3 or the fourth division factor N 4 being different from the first or second division factors N 1 and N 2 , so as to shift the centre of the frequency band defined by the third and fourth factors N 3 and N 4 relative to the programmed frequency of the output signal.