| 摘要 |
PURPOSE:To prevent the production of unnecessary waves, by using the differential amplifier having high input impedance in place of the output transformer of the balanced modulator. CONSTITUTION:The carrier is fed to the primary side of the transformer T1. The modulation wave is fed to the neutral point of the secondary side of the transformer T1. Since the differential amplifier having a high impedance is connected to the output side of the diodes D1-D4 constituting the balanced modulator, the current of modulation wave flows to the load resistor R1 and does not flow to the diodes D1-D4. The level of carrier is made to such a level that the diodes D1-D4 can be turned ON or OFF. Further, since the ON-OFF of the diodes is determined only with the amplitude of the carrier, accurate switching without distortion can be obtained. Accordingly, unnecessary waves can be eliminated from the output of modulation and the modulation signal only can be picked up with the filter. |
