What is an RF Frequency Synthesizer?

A frequency synthesizer is an electronic device that uses an oscillator to generate a signal with a specific frequency or within a pre-set frequency range. They utilize frequency multiplication, frequency division, direct digital synthesis, frequency mixing, and phase-locked loops to generate a stable output signal at a specific frequency with low phase noise.

There are three broad categories of frequency synthesizers:

1. Direct Analog Synthesis
2. Direct Digital Synthesis (DDS) 
3. Indirect Digital (PLL) synthesizers including integer-N and fractional-N.

Frequency synthesizers can be found in various modern devices such as radio receivers, televisions, mobile telephones, radio telephones, walkie-talkies, CB radios, cable television converter boxes, satellite receivers, GPS systems, etc.

Important Parameters for a Frequency Synthesizer:

• Output Frequency (MHz/GHz): It is the frequency or frequency range of the output signal generated by the synthesizer.
• Phase Noise (dBc/Hz): For a carrier frequency at a given power level, the phase noise of a synthesizer is the ratio of the carrier power to the power found in a 1-Hz bandwidth at a defined frequency offset (usually 1 kHz for a synthesizer). Learn more about Phase Noise.
• Reference Frequency: A high quality, low-phase-noise reference is also critical to a stable low-phase-noise RF output. The stability and accuracy of the frequency synthesizer's output are correlated to the stability and accuracy of its reference frequency input.
• Output Power: It is the amplitude of the power of the output signal.
• Spurious and Harmonics (dBc): Spurious and Harmonics are spikes of unwanted signals that are found at the output of a synthesizer. Any unwanted signal synthesized by the synthesizer outside the pre-programmed frequency band can be termed Spurious signal. Harmonics are a subset of Spurious signals found at integer multiples of the fundamental frequency of the signal. Learn more.

everything RF has listed Frequency Synthesizers from the leading manufacturers and made them searchable by specification.