Low phase noise, wide tuning range oscillator utilizing a one port SAW resonator and method of operation

An electronic system comprising:

• at least one subsystem requiring a high-frequency reference signal;
• and
• a phase locked signal generator capable of generating a tunable high-frequency output signal and comprising:
• a reference signal source generator capable of generating a first reference frequency signal;
• a comparator for comparing a phase of said first reference frequency signal and a phase of frequency divided copy of said tunable high-frequency output signal and generating therefrom a frequency tuning signal;
• and
• an oscillator circuit capable of receiving said frequency tuning signal on an input port and generating said tunable high frequency output signal an out put port, said oscillator circuit comprising:
• a tuning element coupled to said input port and selectively altering a resonant frequency for said oscillator circuit to match a desired operating frequency;
• a SAW resonator in series connection with said tuning element between said input and output ports;
• and
• a negative resistance generating circuit in series connection with said SAW resonator between said input and output ports and coupled to an opposite terminal of said SAW resonator form a terminal to which said tuning element is coupled, said negative resistance generating circuit generating a negative resistance at said input port, wherein said negative resistance generating circuit further comprises:
• 1) a transistor coupled at a base to said SAW resonator and at a collector to said output port;
• and 2) at least one capacitor coupled to said base of said transistor.

A method of generating a tunable high frequency output signal, comprising:

• receiving a frequency tuning signal on an input port for an oscillator circuit capable generating the tunable high frequency output signal at an output port for the oscillator circuit, wherein the oscillator circuit oscillates at a resonant frequency only when a reactance at the input port is approximately zero at the resonant frequency and a resistance at the input port is negative at the resonant frequency;
• responsive to receiving the frequency tuning signal on the input port, selectively altering the resonant frequency for the oscillator circuit to match a desired operating frequency, wherein a resistance at the input port is negative at the desired operating frequency and a reactance at the input port is approximately zero at the desired operating frequency;
• and
• generating a negative resistance at the input port at the desired operating frequency utilizing a negative resistance generating circuit coupled to a SAW resonator in series connection with a tuning element, wherein the negative resistance generating circuit comprises:
• 1) a transistor coupled at a base to the SAW resonator and at a collector to the output port;
• and 2) at least one capacitor coupled to the base of the transistor.