Raytheon Company

Richard W Laton

Zvi Galani

Raymond C Waterman, Jr

Gary K Montress

Robert DiBiase

Charles E Chase, Jr

John A Spada

Charles S Ward

A microwave surface acoustic wave resonator stabilized oscillator includes an amplifier having an input terminal and an output terminal and a feedback circuit disposed around said amplifier for providing a closed loop about said amplifier having an integral multiple of 2.pi. radians of phase shift and excess small signal gain at a frequency f.sub.o. The SAW resonator is disposed in the feedback means and is selected to operate in a fundamental mode of operation and provides a resonant circuit having a resonant frequency f.sub.o. The feedback circuit around the amplifier causes the loop to oscillate at a frequency at which the phase shift is an integral multiple of 2.pi. radians and which has excess small signal gain. As the circuit starts to oscillate, the overall gain in the loop is compressed and the loop amplifier is forced to operate in a non-linear region. Operation in non-linear region causes the amplifier to generate harmonics of the fundamental frequency and thus, by providing a circuit which extracts the harmonics of the fundamental frequency, rather than the fundamental frequency itself, the frequency range of the amplifier can be extended. Furthermore, by keeping the fundamental frequency signal in the oscillator loop, the required gain of the loop amplifier may be decreased by up to 3 db and thus can potentially lower the noise floor of the oscillator by comparable figure.

Surface acoustic wave oscillator

An improvement in a microwave oscillator using a GaAs FET as the active element is shown to include a phase detector responsive to a portion of the positive feedback signals applied to a resonator having a high Q and to a portion of the signals out of the GaAs FET, shifted by 90.degree., to obtain signals to degenerate noise internally formed in the GaAs FET.

Microwave oscillator

An improved microwave amplifier is shown to comprise an IMPATT diode in a coaxial circuit coupled to a section of double-ridged waveguide forming a resonant cavity with a low Q, such cavity in turn being coupled to outside circuitry through a compound iris.

Microwave amplifier

A power combiner using a circularly cylindrical cavity, dimensioned to support the TM.sub.020 mode, to combine the power from coaxial diode oscillators is shown to comprise: (a) a first plurality of such oscillators disposed about the periphery of such cavity; (b) a second plurality of such oscillators disposed in coincidence with the first spatial null in the electric field in such cavity; and (c) a plurality, similar in number to the second plurality of such oscillators, of electrically conductive bridges interposed between the top and bottom walls of the cavity in-between the center conductors of the coaxial diode oscillators in the second plurlaity of such oscillators.

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Lexington, MA, United States of America

Richard W Laton