Mitsubishi Denki Kabushiki Kaisha

Yasushi Itoh

Hiromitsu Uchida

Takeshi Ohshima

Takeshi Oshima

Kazuhiko Nakahara

In a microwave module including a transmitting portion circuit and a receiving portion circuit, the transmitting portion circuit and the receiving portion circuit are respectively constructed by transmission lines of different kinds in which polarization planes are orthogonal to each other, and are constructed on the same surface of the same substrate. For example, one of the transmitting portion circuit and the receiving portion circuit is constructed by a microstrip line, and the other is constructed by a coplanar line. Further, one of the transmitting portion circuit and the receiving portion circuit is constructed by a microstrip line, and the other is constructed by a slot line. By this, there is obtained a microwave module in which mutual interference by an electromagnetic field between element circuits in the module can be suppressed, the circuits can be arranged close to each other without requiring a shielding member, and miniaturization of the module can be realized.

Microwave module

By connecting a grounding conductor pattern directly to a grounding terminal of a field-effect transistor and connecting a series circuit comprising a stabilized resistor and an open-circuit stub having a length equal to quarter of a parallel resonance frequency, undesirable parallel resonance caused by the grounding conductor pattern and the open-circuit stub is suppressed, and a voltage drop in the stabilized resistor is suppressed when a bias voltage is applied to the field-effect transistor. Accordingly, the operation of a microwave amplifier is stabilized.

Microwave amplifier optimized for stable operation

A dual-frequency matching circuit of the present invention comprises an output terminal to which a load is connected, an input terminal through which an input signal is input to the load, a series resonance circuit, which is composed of a series capacitor and a series inductor connected in series to the series capacitor and disposed in such a manner that it is connected in series to the load when observed from the input terminal side, and a parallel resonance circuit, which is composed of a parallel capacitor and a parallel inductor connected in parallel to the parallel capacitor, and disposed in such a manner that it is connected in parallel to the entire portion of the load and the series resonance circuit when observed from the input terminal side. By this configuration, the problem contained in the conventional matching circuit that the matching of impedance at two arbitrary different frequencies is not made possible can be solved, and that since no transmission line is needed therein, the circuit can be minimized as a whole when frequency at which the matching operation is performed is set to a low frequency band.

Dual-frequency matching circuit

A microwave amplifier (,) of the present invention contains such an arrangement that both an inductor (,) and a resistor (,) are loaded in a parallel manner between a source electrode of a field-effect transistor (,) and the ground. Since the inductor (,) has a stray capacitance component (B), the inductor (,) is resonated at a resonant frequency &ldquo;f0&rdquo;. However, since the source electrode of the field-effect transistor (,) is grounded via a resistor (,) connected in parallel to the inductor (,), even when the inductor (,) is opened due to a resonant operation, the field-effect transistor (,) is operated under normal condition. As a result, the operation of the microwave amplifier (,) is stabilized.

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Tokyo, Japan

Yasushi Itoh