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An Improved Analog to Digital Conversion Circuit

IP.com Disclosure Number: IPCOM000095621D
Original Publication Date: 1964-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 60K

Publishing Venue

IBM

Related People

Dorrell, CE: AUTHOR [+2]

Abstract

These analog to digital conversion circuits have a transistor amplifier to which the input analog signal is applied and a plurality of transistor switching devices controlled by the amplifier.

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An Improved Analog to Digital Conversion Circuit

These analog to digital conversion circuits have a transistor amplifier to which the input analog signal is applied and a plurality of transistor switching devices controlled by the amplifier.

The base electrodes of the switching devices are connected either to the collector or emitter or both electrodes of the amplifier. The emitter electrodes of the switching devices are selectively connected to different bias potentials so that the base-emitter junctions become forwardly biased at different base input levels. The outputs of the switching devices provide a digital representation of the analog signal level.

In drawing AA, transistors T1, T2 and T3 are normally turned off. V1 is more positive than V2 which, in turn, is more positive than V3. When the input signal to amplifier T1 reaches a first threshold level 2, T1 begins to conduct. Its collector becomes less positive to turn T2 on. When T2 turns on, its output terminal A goes more positive as indicated in the chart. When the input to T1 reaches a second threshold level 3, the potential at the collector of T1 is sufficiently less positive to turn T3 on. When T2 turns on, output A goes positive. When T3 turns on, output B goes positive. Thus, the circuit converts two different levels of analog voltage input into distinctive digital output form.

The circuit of drawing BB converts four levels of analog signal to digital form. T1, T2, T3, T4 and T5 are normally nonco...