Abstract: The modulator system comprises emitter follower type first and second transistor pairs with their emitter electrodes commonly connected, and an emitter follower type third transistor pair with their emitter electrodes commonly connected. Clamped modulation signals having opposite polarities are supplied to the base electrodes of the first transistors of the first and second transistor pairs, whereas signals to be modulated and having opposite polarities are supplied to the base electrodes of the second transistors of the first and second transistor pairs. The base electrodes of the first and second transistors of the third transistor pair are connected to the commonly connected emitter electrodes of the first and second transistor pairs, thereby producing a modulated output signal from the commonly connected emitter electrodes of the third transistor pair.

Abstract: In a differential amplifier comprising first and second transistors of one conductivity type and having emitter electrodes commonly connected, a switching circuit is provided which includes third and fourth transistors of the opposite conductivity type. A switching signal is applied to the base electrodes of the third and fourth transistors, the emitter electrodes thereof are connected to the collector electrodes of the first and second transistors, and the collector electrodes of the third and fourth transistors are connected to the commonly connected emitter electrodes of the first and second transistors. A fifth transistor acting as a constant current source is connected to the commonly connected emitter electrodes of the first and second transistors. In a modified embodiment a sixth transistor is connected in parallel with the fifth transistor to prevent saturation of the third and fourth transistors acting as the switching transistors.