Circuit for holding a pulse during a predetermined time interval and an improved monostable multivibrator

摘要

This invention relates to a circuit for holding a pulse at an up level during a time interval tau after the input signal has been removed, and to the use of the circuit to realize a monostable multivibrator. The holding circuit features a bipolar transistor that is driven into saturation by the application of an input signal in the form of a clock pulse. The hold circuit also features a control network including a diode and a drain resistor. Upon removal of the input signal the charge stored in the base of the saturated transistor is caused by the diode to flow in a controlled manner to the drain resistor so that the transistor is cut off after a time interval tau closely approximating the storage time ts. Thus, the holding circuit provides a pulse of width T+ tau . A monostable multivibrator is obtained by connecting the holding circuit to one of the two inputs of a conventional NOR circuit. The other NOR circuit input receives the input clock pulse. Because of the absence of capacitors these circuits can readily be fabricated as a monolithic integrated form.