Trigger circuit

摘要

The invention relates to methods and apparatus that provide high-speed current pulses. In one embodiment, the trigger circuit provides a current sink pulse as an output. One embodiment of the trigger circuit includes a first input transistor and an output transistor that are emitter coupled to a common resistor. A collector of the first input transistor is alternating current (AC) coupled to a base of the output transistor to drive the output transistor. Advantageously, the AC coupling allows the first input transistor to powerfully drive the output transistor during logic state transitions and yet maintain a low average current. The resistor coupled to the emitter of the first input transistor and the emitter of the output transistor advantageously provides positive feedback or hysteresis feedback, thereby further enhancing the response of the trigger circuit.