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Simple Driver Circuit Providing a Delayed Pulse

IP.com Disclosure Number: IPCOM000089677D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 49K

Publishing Venue

IBM

Related People

Harroun, TV: AUTHOR

Abstract

This driver circuit, having a delayed output, is simple, requiring only a few active devices, and yet does not produce high stress levels.

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Simple Driver Circuit Providing a Delayed Pulse

This driver circuit, having a delayed output, is simple, requiring only a few active devices, and yet does not produce high stress levels.

In the operation of the circuit illustrated in Fig. 1, in its quiescent state, the restore pulse RS is at a high level and the input signal Vin is low; thus the gate electrodes of transistors TD and TG are high, turning on TD and TG. The output signal Vout is thus at a low level. Since the gate electrode of transistor TC is low, there is no direct current path through the circuit dissipating power. To begin a cycle, the restore pulse RS is dropped to a low level, and thereafter the input signal Vin rises, as indicated in Fig. 3. When the input signal Vin rises, capacitor CF begins to be charged, and the gate electrodes of transistors TD and TG are driven harder due to the application of the input signal Vin across capacitor CT, which maintains transistor TC in the off condition.

As capacitor CF is charged, the drain voltage of transistor TE rises, eventually pulling the gate electrode of transistor TC above threshold, turning on transistor TC. Transistor TC now begins discharging capacitor CT and thus reducing the gate electrode voltage of transistors TD and TG. Transistors TC, TD and TE form a feedback loop which rapidly pulls the gate electrodes of transistors TD and TG to ground, turning off transistors TD and TG. The output signal Vout now rises rapidly, bootstrapping the gate electrode of transistor TF to a high voltage due to the charge accumulated on capacitor CF. When the input signal Vin drops to a low value and the restore pulse RS goes to a high value, Vout will again drop to a low value, as described above. If desired, transistors TE may be replaced by a short circuit, if higher stresses can be tolerated in the driver circuit.

The circuit shown in Fig. 1 may be modified as in Fig. 2 to generate an output signal Vout having a plurality of successively increasing slopes, as indicated in Fig. 3, which is desired for driving certain latch circuits.

In the operation of the circuit illustrated in Fig. 2, in the quiescent state, the restore pulses RS and RS' are high and the inp...