| 摘要 |
A doubly balanced demodulator for developing four audio difference components from a composite baseband signal comprises a constant current source and a differential amplifier comprised of a pair of transistors. The constant current source is coupled to the emitters of the differential amplifier transistors, the base of one of the amplifier transistors is coupled to the source of composite signal and the base of the other transistor is returned to a source of bias potential. The demodulator further includes a utilization circuit having four input terminals. One transistor of the transistor amplifier pair is coupled to the utilization circuit by a first switch comprising four current splitting transistors while the other differential amplifier transistor is coupled to the utilization circuit via a second switch likewise comprising four current splitting transistors. A switch activating means renders selected ones of the current splitting transistors conductive and, alternately, the remaining ones of the current splitting transistors conductive, to enable the conducting current splitting transistors to translate segments of the composite signal and to collectively apply these segments to the utilization circuit to enable that circuit to develop four audio difference components.
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