Sharp Kabushiki Kaisha Corporation

Masayuki Nibe

Masahiro Kato

A rat race circuit has an annular transmission line formed on a microstrip dielectric substrate. A terminal for portis formed at any given position of the annular transmission line. Respective terminals for portand portare formed at respective positions distant from the position of portin the counter-clockwise and clockwise directions each by a distance of &#x3bb;g/4 (&#x3bb;g: effective wavelength). Moreover, at the position distant from the position of portin the counter-clockwise direction by the distance of &#x3bb;g/4, a terminator resistor (R=50&#x3a9;) is formed. A local oscillator signal is supplied to port, and first and second mixer inputs are connected respectively to portand port. The local oscillator signal divider and a low noise converter using the divider are thus provided that are scarcely influenced by matching with respect to mixers and provide stable performance and high isolation.

Local oscillator signal divider and low-noise converter employing the same

A local oscillator has the following construction so that easier design can be achieved, stable oscillation characteristic can be provided and the manufacturing cost can be reduced. A high impedance line, a ground pattern with a through hole, and a coupling line are formed on a printed circuit board. A chip part, such as HEMT, and a dielectric resonator are mounted thereon by die bonding. A terminal of HEMT is connected to the pattern formed on the printed circuit board by wire bonding. A drain terminal of the HEMT is connected to a bias circuit. The bias circuit includes a stub for grounding, a high impedance line, and a chip capacitor.

Local oscillator having improved oscillation characteristic

In a low-noise amplifying device, an antenna point is attached to a tip portion of a microstrip line and an end surface of a printed wiring board. The printed wiring board is fixed to a chassis by a screw, a rivet, a projecting portion of a frame or a conductive adhesive in the vicinity of a connection of the antenna pin to the microstrip line. Thereby, even a slight warp that might exist on the board is corrected, so that adhesion between the board and the chassis is reinforced and the low-noise amplifying device stably operates.

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Osaka, Japan

Masayuki Nibe