Mobile radio frequency synthesizers based on surface acoustic wave oscillators

Delay-stabilized surface acoustic wave oscillators are attractive for use as stable, low-noise sources in digital frequency synthesizers for mobile radio. Here the design and operating principles of the surface acoustic wave oscillator are briefly reviewed. Its application is subsequently detailed in three experimental frequency synthesizer modules, which phase lock the surface acoustic wave oscillator to a reference crystal oscillator to achieve the superior stabilization required in mobile radio applications. First a single channel u.h.f. synthesizer is described which possesses superior efficiency when compared with conventional frequency multiplier based transmitters. Later digital dividers are added extending this module into multichannel synthesizers which ultimately have potential applications in h.f., v.h.f. and u.h.f. mobile radio systems.