| 摘要 |
A filter circuit includes a differential amplifier having a mutual conductance of gm1, and a transistor T1 which attenuates an output current of the differential amplifier by 1/ beta ( beta is a current amplification factor) is arranged at a stage succeeding to the differential amplifier, whereby terms of gm1 in equations respectively representative of a resonance frequency omega 0 and a quality factor Q are multiplied by 1/ beta , respectively. Since the term of gm1 exists in a numerator within a root symbol ( 2ROOT +E,rad +EE ) in the equation representative of the resonance frequency omega 0, by arranging the transistor T1, the resonance frequency omega 0 can be decreased by 1/ 2ROOT +E,fra +EE beta times. Furthermore, since the term of gm1 exists in a denominator within a root symbol ( 2ROOT +E,rad +EE ) in the equation representative of the quality factor Q, by arranging the transistor T1, the quality factor can be increased by 2ROOT +E,rad +EE beta times.
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