초록 ▼

An op amp clamp for charging or discharging a capacitor prevents the voltage on the capacitor from going beyond a reference voltage determined by a reference clamp voltage applied to an input of a differential amplifier. The second input of the differential amplifier is connected to the capacitor. T

An op amp clamp for charging or discharging a capacitor prevents the voltage on the capacitor from going beyond a reference voltage determined by a reference clamp voltage applied to an input of a differential amplifier. The second input of the differential amplifier is connected to the capacitor. The output of the differential amplifier is provided in a feedback loop to the capacitor. The feedback loop includes a charging circuit or a discharging circuit depending upon the function of the op amp clamp. The feedback loop may be arranged with a current mirror in which current generated by the output of the differential amplifier is mirrored in the charging or discharging circuit. A signal to activate charging or discharging is applied at the output of the differential amplifier to activate or deactivate the current mirror.

대표청구항 ▼

[ We claim:] [1.] An op amp clamp comprising:a node, having a voltage, connected to a capacitor;a first transistor, having a base, an emitter and a collector, for applying a current to the capacitor to change the voltage of said node;signal means coupled to said first transistor, for receiving an ap

[ We claim:] [1.] An op amp clamp comprising:a node, having a voltage, connected to a capacitor;a first transistor, having a base, an emitter and a collector, for applying a current to the capacitor to change the voltage of said node;signal means coupled to said first transistor, for receiving an apply signal that activates said first transistor; anda differential amplifier having a first input connected to a reference clamp voltage and a second input coupled to said node and having an output coupled to said node through a feedback loop connected to said first transistor; anda second transistor in the feedback loop having a collector connected to the output of said differential amplifier, a base connected to the base of said first transistor and an emitter, wherein said op amp clamp responds to a presence of the apply signal by achieving a state in which said node is held at a reference voltage determined by the reference clamp voltage.