Synthesizers incorporating parascan TM varactors
View Patent ↗A synthesizer incorporating voltage tunable capacitors, 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.
1. A synthesizer incorporating voltage tunable capacitors, comprising:
at least one resonator coupled into a base circuit of a bipolar transistor, said at least one resonator including at least one voltage tunable capacitor;
said 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 said output of said RF filter and providing an input to a controller;
an integral switch mode power supply providing power to said base circuit via a first power supply filter, and said controller via a second power supply filter; and
said controller scales a user-selected control voltage range to levels required by said at least one voltage tunable capacitors associated with said at least one resonator.
2. The synthesizer incorporating voltage tunable capacitors of claim 1 , wherein said at least one resonator is at least one at micro strip resonator.
3. The synthesizer incorporating voltage tunable capacitors of claim 1 , wherein said bipolar transistor is a Si-bipolar transistor.
4. The synthesizer incorporating voltage tunable capacitors of claim 1 , wherein said emitter of said bipolar transistor is further terminated into a short-circuited micro strip stub.
5. The synthesizer incorporating voltage tunable capacitors of claim 1 , wherein said buffer amplifier is replaced with a circulator associated with said impedance matching circuit.
6. The synthesizer incorporating voltage tunable capacitors of claim 1 , further comprising at least one additional buffer amplifier in the output circuit.
7. The synthesizer incorporating voltage tunable capacitors of claim 1 , wherein said controller is a simple one-transistor controller.
8. A method of controlling an synthesizer using voltage tunable capacitors, comprising:
providing at least one resonator coupled into a base circuit of a bipolar transistor, said at least one resonator including at least one voltage tunable capacitor;
said 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;
providing a frequency divider, programmable phase locked loop and loop filter receiving said output of said RE filter and providing an input to a controller;
providing an integral switch mode power supply providing power to said base circuit via a first power supply filter, and said controller via a second power supply filter; and
scaling a user-selected control voltage range via said controller to the levels required by said at least one voltage tunable capacitor associated with said at least one resonator.
9. The method of controlling an synthesizer using voltage tunable capacitors of claim 8 , wherein said at least one resonator is at least one at micro strip resonator.
10. The method of controlling an synthesizer using voltage tunable capacitors of claim 8 , wherein said bipolar transistor is a Si-bipolar transistor.
11. The method of controlling an synthesizer using voltage tunable capacitors of claim 8 , wherein said emitter of said bipolar transistor is further terminated into a short-circuited micro strip stub.
12. The method of controlling an synthesizer using voltage tunable capacitors of claim 9 , further comprising the step of providing a buffer amplifier associated with said impedance matching circuit.
13. The method of controlling an synthesizer using voltage tunable capacitors of claim 8 , further comprising the step of providing a circulator associated with said impedance matching circuit.
14. The method of controlling a synthesizer using voltage tunable capacitors of claim 8 , further comprising the step of providing a buffer amplifier in the output circuit.
15. The method of controlling an synthesizer using voltage tunable capacitors of claim 8 , wherein said controller is a simple one-transistor controller.