Patent ID: 8890590

Claim:
A wideband frequency synthesizer, comprising: a phase-locked loop unit, receiving a reference signal and a feedback signal, and generating a first oscillating signal according to the reference signal and the feedback signal; a first voltage-controlled oscillating unit, generating a second oscillating signal; and a first frequency mixer unit, coupled to the phase-locked loop unit and the first voltage-controlled oscillating unit, receiving the first oscillating signal and the second oscillating signal, and mixing frequencies of the first oscillating signal and the second oscillating signal to generate an output signal, and taking the output signal as the feedback signal for outputting to the phase-locked loop unit, wherein the first frequency mixer unit comprises: a frequency mixer, coupled to the phase-locked loop unit and the first voltage-controlled oscillating unit, receiving the first oscillating signal and the second oscillating signal, and mixing a frequency of the first oscillating signal by using the second oscillating signal to generate a frequency mixing signal; a frequency mixing filter, coupled to the frequency mixer, receiving the frequency mixing signal, and performing a low-pass filtering or a high-pass filtering on the frequency mixing signal to generate the filtered frequency mixing signal; and a selection unit, coupled to the phase-locked loop unit and the frequency mixing filter, and selecting to output the first oscillating signal or the frequency mixing signal to generate the output signal.