Frequency adjustable oscillator and methods of operation

1. An oscillator for generating a signal with an adjustable frequency in a frequency range of radio frequency (RF), microwave, and millimeter wave frequencies, said oscillator including:

a loop circuit having:

an amplifier or gain block;

a delay element or filter;

a phase shifter including a vector modulator to provide an unlimited range of phase shift adjustment;

means for adjusting the phase of said phase shifter, said adjusting means being coupled to said phase shifter; and

means for providing an output signal.

2. The oscillator according to claim 1 , for use in the frequency range from 1 GHz to 200 GHz.

3. The oscillator according to claim 1 , wherein said loop circuit has a feedback path including said phase shifter and said delay element or filter.

4. The oscillator according to claim 3 , wherein said filter is a bandpass filter.

5. The oscillator according to claim 3 , wherein said phase shifter and said gain block are implemented in MMICs.

6. The oscillator according to claim 1 , wherein said adjusting means is electronically controllable.

7. The oscillator according to claim 6 , wherein said electronically controllable adjustment is effected by adjusting the phase shift of said vector modulator.

8. The oscillator according to claim 1 , wherein said delay element or filter is a multi-section bandpass filter, the multi-section filter bandpass characteristic being fixed or electronically controlled.

9. The oscillator according to claim 8 , wherein said multi-section bandpass filter is a multi-resonator filter.

10. The oscillator according to claim 9 , wherein the resonator is a high Q device, including a stripline or waveguide filter.

11. The oscillator according to claim 10 , wherein a passband of said waveguide filter is mechanically adjustable to change a tuning range.

12. The oscillator according to claim 11 , further including a yttrium iron garnet (YIG) tuned filter, a passband of said filter being electronically adjustable.

13. The oscillator according to claim 1 , wherein said means for providing an output signal is located at any point in said loop circuit, wherein said providing means is a power splitter or a coupler.

14. The oscillator according to claim 3 , further including:

a frequency divider (or harmonic mixer) operating on said output signal; and

a comparator coupled to said loop circuit and said vector modulator to compare a frequency of a signal in said loop circuit with the frequency of a reference signal, a difference in said frequencies used to control said phase shifter.

15. The oscillator according to claim 14 , wherein said comparator provides a first output (coarse) phase adjusting signal to said vector modulator and a second output (fine) phase adjusting signal to adjust the phase shift of said loop.

16. The oscillator according to claim 15 , wherein said first output phase adjusting signal includes an in-phase signal and a quadrature signal.

17. The oscillator according to claim 14 , wherein said comparator includes a phase-locked loop circuit providing phase-locked loop control which can include frequency and/or phase locking to a reference signal.

18. A method of adjusting the frequency of oscillation of an output signal from an oscillator, operating in a frequency range of radio frequency (RF), microwave, and millimeter wave frequencies, said method including the steps of:

providing said oscillator including a loop circuit having:

an amplifier or gain block;

a delay element or filter;

a phase shifter including a vector modulator to provide an unlimited range of phase shift adjustment;

means for adjusting said phase shifter, said adjusting means being coupled to said phase shifter; and

means for providing said output signal;

adjusting a phase shift of said phase shifter to adjust the frequency of oscillation of said oscillator to a required frequency.

19. The method according to claim 18 , for use in the frequency range from 1 GHz to 200 GHz.

20. A method of providing an output signal of a required frequency from an oscillator, said output signal being adjustable in a frequency range of radio frequency (RF), microwave, and millimeter wave frequencies, said method including the steps of:

providing said oscillator including a loop circuit having:

an amplifier or gain block;

a delay element or filter;

a phase shifter including a vector modulator to provide an unlimited range of phase shift adjustment;

means for adjusting said phase shifter, said adjusting means being coupled to said phase shifter; and

means for providing the output signal; and

adjusting a phase shift of said phase shifter so as to adjust a frequency of said output signal to a required frequency.

21. The method according to claim 18 , for use in the frequency range from 1 GHz to 200 GHZ.

22. An oscillator for generating a signal with an adjustable frequency in a frequency range of radio frequency (RF), microwave, and millimeter wave frequencies, said oscillator including:

a loop circuit having:

an amplifier or gain block;

a delay element or filter;

a phase shifter including a vector modulator providing an unlimited range of phase shift adjustment, said delay element or filter and said phase shifter contained in a feedback path of said loop circuit;

a power splitter or coupler to provide an output signal; and

a controller coupled to said phase shifter to adjust the phase of said phase shifter.

23. The oscillator according to claim 22 , wherein said power splitter or coupler is a three-way split coupler.

24. The oscillator according to claim 22 , for use in the frequency range from 1 GHz to 200 GHz.

25. An oscillator for generating a signal with an adjustable frequency in a frequency range of radio frequency (RE), microwave, and millimeter wave frequencies, said oscillator including:

a loop circuit having:

an amplifier or gain block;

a delay element or filter;

a phase shifter including a vector modulator providing an unlimited range of phase shift adjustment, said delay element or filter and said phase shifter contained in a feedback path of said loop circuit;

a power splitter or coupler to provide an output signal; and

a phase and frequency meter and a loop filter coupled to said phase shifter to adjust the phase of said phase shifter.

26. The oscillator according to claim 25 , wherein said power splitter or coupler is a three-way split coupler.

27. The oscillator according to claim 25 , for use in the frequency range from 1 GHz to 200 GHz.