Synthesizers incorporating parascan TM varactors

A synthesizer incorporating voltage tunable capactiors, comprising at least one resonator coupled into a base circuit of a bipolar transistor, the at least one resonator including at least one voltage tunable capacitor; the bipolar transistor including a collector which terminates in a radial micro strip stub and an emitter which produces an output via an impedance matching circuit, a buffer amplifier and an RF filter; a frequency divider, programmable phase locked loop and loop filter receiving the output of the RF filter and providing the input to a controller; an integral switch mode power supply providing power to the base circuit via a first power supply filter, and the controller via a second power supply filter. The controller scales the user-selected control voltage range to the levels required by the voltage tunable capacitors associated with the at least one resonator. The resonator of the synthesizers incorporating parascan™ varactors of the present invention can be at least one at micro strip resonator and the bipolar transistor can be a Si-bipolar transistor. The emitter of the bipolar transistor is further terminated into a short-circuited micro strip stub, thus preventing lower modes of oscillation to exist. The present invention can further comprise a buffer amplifier or circulator associated with the impedance matching circuit to reduce the pulling effect where needed. Also, the present invention can further comprise a buffer amplifier in the output circuit to amplify the output power where needed. In a preferred embodiment of the present invention the controller can be a simple one-transistor controller and the controller can have a user-specified frequency response, thus aiding integration with phase-locked loop synthesizers.