Sughrue, Mion, Zinn, Macpeak & Seas, PLLC
Demodulator circuit using gyrator circuit
 A demodulator circuit includes a gyrator circuit forming a derived equivalent inductance which is used in a demodulating circuit. The gyrator circuit has a first operational transconductance amplifier and a second operational transconductance amplifier, wherein a second input terminal of the first operational transconductance amplifier is connected to a first output terminal of the second operational transconductance amplifier. A second output terminal of the first operational transconductance amplifier is connected to a second input terminal of the second operational transconductance amplifier. Both of the second input terminal of the first operational transconductance amplifier and the second input terminal of the second operational transconductance amplifier are grounded via a constant dc voltage. A first output terminal of the first operational transconductance amplifier is connected to a first input terminal of the second operational transconductance amplifier. A capacitor is connected between the first and second output terminals of the first operational transconductance amplifier. A first input terminal of the first operational transconductance amplifier serves as an input terminal to the gyrator circuit. The capacitance C of the capacitor is determined so that C=LG.sup.2, where L stands for the desired equivalent inductance of the gyrator circuit as viewed from the input terminal thereof and G stands for the transconductance of each of the operational transconductance amplifiers employed in the gyrator circuit. 
NEC Corporation
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inventional inventional inventional
Tomohiro
Fujii