Matsushita Electric Industrial Co., Ltd.

Toshihide Tanaka

Hiroshi Saka

Tsuyoshi Mekata

Kentaro Setsune

Yoshikazu Yoshimura

Mitsuo Isobe

Namio Yamaguchi

Susumu Ide

Tetsuo Kutsuki

Seiji Fujisawa

Yasuhumi Shiomi

A feedback type microwave oscillator using a three-terminal active element employs both series feedback and parallel feedback and capacitance in its output circuit, thereby increasing the small signal negative resistance, and the output power and its resistance to impedance fluctuations of a load attached thereto.

Microwave oscillator having series and parallel feedback

A dielectric resonator microwave oscillator in which the gate of a FET is connected to a resonance circuit. An inductor is connected to the drain of the FET, and the output is taken from the source of the FET. This dielectric resonator microwave oscillator has enhanced negative resistance and positively starts the oscillation even when there is a low reflection coefficient of the resonance circuit. Using a circuit which consists of a capacitor and inductor between the source and the output terminal, a further increasing of negative resistance at the gate of the FET is obtained.

Dielectric resonator microwave oscillator having enhanced negative

In a waveguide-to-microstrip line coupling arrangement, a microstrip line is placed on an outer surface of a wall of a waveguide which is coupled with the microstrip line via a metallic post connected at its one end to a center strip conductor of the microstrip line and is inserted inside the waveguide via through-holes made in a ground plane of the microstrip line and in the wall of the waveguide where the diameter of the through-hole made in the ground plane is made smaller than that of the through-hole made in the wall of the waveguide. The waveguide has a short-circuited end and the metallic post is placed close to the short-circuited end. The coupling arrangement may be used in a microwave frequency converter having an microwave integrated circuit including a local oscillator and a mixer, where the MIC is located on an outer surface of a longitudinal wall extending from a short-circuited end to an open end.

Waveguide-to-microstrip line coupling arrangement and a frequency

A microwave integrated circuit comprises a shield case having a pair of opposed first and second end walls, a pair of side walls and top and bottom walls, and a dielectric substrate on the bottom wall. First and second interconnected integrated circuit portions are arranged on the substrate between the first and second end walls. An input strip line is arranged on the substrate, the strip line having one end coupled to the input of the first integrated circuit portion and the other end terminating at a position spaced from the first end wall by a distance approximately equal to an integral multiple of the half wavelength of a signal propagating in the shield case. An elongated coupling member is disposed in parallel with the first end wall, the coupling member extending from the other end of the input strip line to an external circuit.

Microwave integrated circuit immune to adverse shielding effects

An input matching circuit for a first stage amplifying element of a microwave preamplifier comprises at least one capacitive open-ended stub which is located in the vicinity of an input terminal of the first stage amplifying element so that the structure of the input matching circuit is simple. Input impedance of the first stage amplifying element is designed to assume a state of impedance matching for minimum noise, while the distance between the first stage amplifying element and a second stage amplifying element is appropriately determined with an input matching circuit of the second stage amplifying element being appropriately set. With this arrangement input VSWR of the preamplifier is set to a value smaller than an input VSWR of the first amplifying stage, and therefore it is possible to provide a microwave preamplifier which shows satisfactory input VSWR characteristic and noise figure such that the input VSWR of the preamplifier is improved when compared with the input VSWR exhibited on impedance matching for minimum noise while the noise figure is less deteriorated compared to the noise figure exhibited on impedance matching for minimum noise.

Microwave preamplifier

In a synchronous video detector circuit using a phase-locked loop, the synchronous detection of a video IF signal is effected with a synchronous carrier signal reproduced by the PLL including a voltage-controlled oscillator. Each of a phase comparator of the PLL and a synchronous video detector has its input terminal connected to an output terminal of a video IF amplifier by untuned coupling, and arranged on the output side of the synchronous video detector is a phase-locked mode detector for detecting that the PLL is in its phase-locked mode. The phase-locked mode detector is adapted to control the band width of a low-pass filter of the PLL in either a narrow band mode or a wide band mode and the low-pass filter is controlled to operate in the narrow band mode only when the PLL is in the phase-locked mode of operation. The black and white noise included in the output signal of the synchronous video detector are both cancelled by a noise cancellation circuit including a black noise detector for pulse noise cancellation purposes.

Synchronous video detector circuit using phase-locked loop

In a mixer using a planar circuit such as a strip line or a microstrip line etc., an IF signal interruption circuit which passes an RF signal but exhibits an open-circuit impedance against an IF signal is provided in shunt with a main line on which the RF signal propagates toward a mixer diode, and a low-pass filter is connected in the vicinity of the IF signal interruption circuit in order to short-circuit a mount point of the diode for the IF signal by high frequency short-circuiting technique wherein an open-ended quarter-wavelength transmission line or a short-circuited half-wavelength transmission line is used, whereby low noise performance can be obtained over a wide frequency band even under such an operating condition that the IF signal is in the GHz band.

Microwave integrated circuit mixer

A surface acoustic wave (SAW) device includes a SAW element disposed on a printed circuit. The printed circuit has an insulation substrate having input and output wiring conductors and input side and output side grounding conductors formed thereon. Interdigital transducers of the SAW element are connected to the input and output wiring conductors. The input side grounding conductors and the output side grounding conductors are disposed apart from each other with an isolation gap inbetween, thereby obtaining desirable filtering characteristics by suppressing undesirable coupling between input side and output side caused by a feed through electromagnetic wave.

Surface acoustic wave device

A television receiver comprising a first printed circuit board having a helical resonator filter, an adjacent channel trap circuit and an impedance converter circuit for providing a reduced output impedance, the first printed circuit board being secured to the tuner casing, and a second printed circuit board having first and subsequent i-f amplifier stages, the two printed circuit boards being connected to each other, whereby good skirt characteristics can be simply obtained. Also, no overall adjustment is required but the tuner and i-f amplifier may be adjusted separately, thus providing improved serviceability.

Growing community of inventors

Ikoma, Japan

Toshihide Tanaka