| 摘要 |
PURPOSE:To obtain an intermediate-frequency amplifier circuit which is excellent in electric field detecting characteristic and can be constituted to an integrated circuit easily, by connecting in parallel a transistor (TR) pair, whose emitters are commonly connected, with another TR pair, into which emitter resistances that become the 1st input pair of the double balanced differential amplifier of the last stage. CONSTITUTION:An IF signal input voltage VIN is level-shifted by means of transistors (TR) Q53 and Q54 after amplification by means of the 1st-stage differential amplifier composed of TRs Q51 and Q52. Amplification and level shifting are successively repeated on the input voltage VIN and the differential output of TRs Q91 and Q92 is outputted as an IF signal output voltage VO. Since the input signal to each double balanced differential amplifier is successively amplified by differential amplifiers, the level becomes higher as going to the later stage and successively saturated from the 4th-stage differential amplifier. Therefore, when the saturation level of the 1st-stage double balanced differential amplifier is raised or the sensitivity of the final-stage differential amplifier is made higher, the dynamic range of electric field detection can be enlarged if electric field detection is performed by connecting double-wave rectifiers in multiple stages.
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