Negative resistance oscillator with electronically tunable base inductance
AssigneeHewlett-Packard Company
InventorThomas M. Higgins, Jr.
Life of this patent
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Abstract
Problems associated with compromise, fixed base inductances in negative resistance oscillators are overcome by use of an electronically tunable base network. Parameters such as phase noise and output power can thereby be optimized over a wide range of operating conditions. The disclosure is illustrated with reference to a 500-1000 Mhz voltage controlled oscillator employing base-tuning varactors that are slaved to the VCO's tuning signal.
Claims15
An oscillator comprising:
- an active device having first, second and third terminals;
- a tank circuit having a resonant frequency, the tank circuit being coupled to the first terminal, said resonant circuit including a first circuit element responsive to a first signal for varying the resonant frequency of said tank circuit;
- an output coupled to the third terminal for providing an oscillator output signal;
- said oscillator having an operational characteristic other than frequency which is dependent, at least in part, on a reactance presented to the second terminal of the active device by a network coupled thereto;
- said network coupled to the second terminal including a second circuit element responsive to a second signal for varying the reactance presented to the second terminal by the network;
- and
- means for providing to the second circuit element with the second signal, said second signal tending to optimize said characteristic as a function of oscillator frequency.
In a method of operating an oscillator, the oscillator including an active device that has a base terminal thereof coupled to ground through a base network, the base network serving to couple RF signals between the base terminal and ground, an improvement comprising electronically altering a reactance of the base network without changing the topology of said network so as to tailor a parameter of oscillator operation as a function of frequency.
In a method of operating a voltage controlled oscillator over a range of frequencies, the oscillator including a tank circuit having a resonant frequency responsive to a tuning voltage applied to a varactor therein, the tank circuit being coupled to a transistor, the transistor presenting to the tank circuit an impedance, any reactive part of said impedance serving to pull an oscillator output frequency from said resonant frequency, an improvement comprising applying an optimizing voltage to a reactive element in a network coupled to a transistor base terminal so as to reduce the reactive part of the impedance presented to the tank circuit by the transistor while still permitting oscillation, and without changing a topology of said network.
Dependencies are inferred from the claim text.