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Gated Oscillator

IP.com Disclosure Number: IPCOM000045701D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 39K

Publishing Venue

IBM

Related People

Marshall, SE: AUTHOR [+2]

Abstract

An integrated circuit gated oscillator produces in response to a gating signal a series of well-defined pulses, that is, pulses with closely toleranced mark/space ratio and with the first pulse of the series substantially identical to subsequent pulses. Further, the oscillator starts and stops immediately on edges of the gating signal.

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Gated Oscillator

An integrated circuit gated oscillator produces in response to a gating signal a series of well-defined pulses, that is, pulses with closely toleranced mark/space ratio and with the first pulse of the series substantially identical to subsequent pulses. Further, the oscillator starts and stops immediately on edges of the gating signal.

The oscillator circuit is shown in Fig. 1, with relevant voltage waveforms shown in Fig. 2. Assuming that a gating signal (waveform (a) Fig. 2) applied to input terminal 1 is at an up level such that transistor T6 is on and saturated, then capacitor C1 is charged by constant current I through diode connected transistor T1 until the cathode of transistor T1 reaches about 4 V. When this occurs, the constant current I is diverted through transistor T2, the base voltage of which is set to about 4 V by the potential divider resistors R4 and R5. When the input voltage on terminal 1 falls below approximately 0.7 V, transistor T6 ceases to conduct and the collector current of transistor T2 turns on the current mirror network consisting of transistors T3, T4 and T5, producing about 1 ma of current in the collectors of transistors T3 and T5. This immediately pulls the output at terminal 2 down from 4 V to +1 V (waveform (c) Fig. 2) and starts discharging capacitor C1.

Discharge continues until the cathode of transistor T1 reaches about 1 V at which time the constant current I will be diverted away from transistor T2 and will...