A frequency synthesizer is provided. The frequency synthesizer includes a jitter-cleaning phase-locked loop, a fractional phase-locked loop, a mixer, and a radio-frequency phase-locked loop. The jitter-cleaning phase-locked loop receives a reference clock and a mixed signal, and suppresses a jitter of the reference clock to generate a first oscillating signal based on the reference clock and the mixed signal. The fractional phase-locked loop receives the reference clock and generates a second oscillating signal based on the reference clock. The mixer mixes the first oscillating signal and the second oscillating signal to generate the mixed signal. The radio-frequency phase-locked loop receives the first oscillating signal and generates an output signal based on the first oscillating signal.

A communication apparatus including a first mixer configured to generate an analog output signal (X.sub.OUT) from an analog input signal (X.sub.IN) using a first mixing signal, a second mixer configured to generate an analog output signal (Y.sub.OUT) from an analog input signal (Y.sub.IN) using a second mixing signal, and a local oscillator configured to provide a reference frequency (f.sub.REF), where the first mixer is configured to derive a first sampling frequency (f.sub.S,1) from the f.sub.REF, and where the second mixer is configured to derive a second sampling frequency (f.sub.S,2) from the f.sub.REF.

A communication apparatus including a first mixer configured to generate an analog output signal (X.sub.OUT) from an analog input signal (X.sub.IN) using a first mixing signal, a second mixer configured to generate an analog output signal (Y.sub.OUT) from an analog input signal (Y.sub.IN) using a second mixing signal, and a local oscillator configured to provide a reference frequency (f.sub.REF), where the first mixer is configured to derive a first sampling frequency (f.sub.S,1) from the f.sub.REF, and where the second mixer is configured to derive a second sampling frequency (f.sub.S,2) from the f.sub.REF.