Denso Corporation

Ryu Kimura

Hiroaki Hayashi

Hisanori Uda

Kazuo Mizuno

Yoshiyuki Kago

Yukiomi Tanaka

Kazuhiko Endo

Two lines Ai(i=1 or 2) are connected to an input terminal In. The line Ais grounded via a capacitor C. The line Aand a line Bform a coupled line. One end of the line Bis connected to a positive pole of a diode Dwhich is grounded at its negative pole. Lines Band Bare connected to the other end of the line B. The other end of the line Bis connected to a capacitor Cwhich is grounded at its other end and a resistor Rwhich is connected to a voltage control terminal Vat its other end. The other end of the line Bis connected to the positive pole of a diode D. The line Band the line Aform a coupled line. One end of the line Ais connected to an output terminal Out-i, and the other end is grounded via a capacitor C. The output of the terminals Out-are switched to 5.8 GHz band, 4.8 GHz band and cut-off, by applying to Vand Vthree potentials, that is, ground potential. positive potential which causes no current flow and positive potential which causes current flow.

Filtering type frequency switching circuit

A start signal outputting circuit according to the invention has a differential RF/DC convertor partfor converting a high frequency power (RF) into a d.c. potential (DC). The RF/DC convertor partis formed by two transistors Q, Qworking as a diode, and transistors Q, Qand resistances Rfor forming high resistances at anode sides and cathode sides of these diodes, respectively. A differential amplification partdisposed at a later stage of the diode has not only amplifying effect but also low-pass filtering effect together with filtering parsof its previous and later stages. In this case, it is designed so that current flowing through the respective circuits is about 2&#x2dc;3 &#x3bc;A. As a result, even if the high frequency power of the specified frequency is weak, for example &#x2212;60&#x2dc;&#x2212;40 dBm, a start signal outputting circuitwhich outputs a d.c. potential of 0.3&#x2dc;2.4V, is suitable for integration and has a low power consumption can be obtained.

Start signal outputting circuit

A start signal output circuit having an RF/DC conversion circuit to which radio frequency power (RF) of specified frequency is inputted and from which a direct current potential (DC) is outputted, comprises a detection/amplification circuitwhich includes a voltage doubler wave-detector circuitconfigured including a sensing diode Q(Tr) for sensing the RF power, a differential amplifier including differential pair transistors Trand Tr, and a current mirror circuit. A base current of one Trof the differential pair transistors is brought into substantial agreement with a DC component of a current flowing through the sensing diode Q(Tr). A total of currents flowing through the differential pair transistors Trand Tris regulated to a substantially constant value by the current mirror circuit. Thus, the start signal output circuit which is small in size, high in sensitivity and low in power consumption can be realized.

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Chita-gun, Japan

Ryu Kimura