Primarily because of its cost efficiency and reduced circuit complexity, this technique has found increasing use in modern electronic components such as DACs, ADCs, frequency synthesizers, switched-mode power supplies and motor controllers.
22.
While modern frequency synthesizers can output a clean stable signal up through UHF, for many years, especially at higher frequencies, it was not practical to operate the oscillator at the final output frequency.
23.
Varicaps are used for frequency modulation of oscillators, and to make high-frequency voltage controlled oscillators ( VCOs ), the core component in phase-locked loop ( PLL ) frequency synthesizers that are ubiquitous in modern communications equipment.
24.
The most common use is in broadband frequency synthesizers, where the high frequency signals act as stable references correlated to the lower energy references; the outputs can be used directly, or to synchronize phase-locked loop oscillators.
25.
San Diego-based Peregrine Semiconductor has used silicon on sapphire ( SOS ) technology to develop RF integrated circuits ( RFICs ) including RF switches, digital step attenuators ( DSAs ), phase locked-loop ( PLL ) frequency synthesizers, prescalers, mixers / upconverters, and variable-gain amplifiers.
