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Analog to Digital Converter

IP.com Disclosure Number: IPCOM000097656D
Original Publication Date: 1961-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 50K

Publishing Venue

IBM

Related People

Chargois, DF: AUTHOR [+2]

Abstract

A group of Esaki diodes, in series between a reference voltage ramp generator and an analog voltage input, provides a series of transition outputs which are counted to provide a digital equivalent of the analog input.

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Analog to Digital Converter

A group of Esaki diodes, in series between a reference voltage ramp generator and an analog voltage input, provides a series of transition outputs which are counted to provide a digital equivalent of the analog input.

In the top drawing, the sample oscillator controls the frequency of sampling by resetting all other units and starting the ramp generator. The oscillator frequency is at least double that of the analog input.

In the ramp generator, T(1) is a switch which, when turned off, allows T(2) to become a current source for charging C(1). The voltage across C(1) is a ramp over the period involved. The ramp voltage is fed into T(3) which is operated common collector, providing a voltage source for switching Esaki diodes E(1)... E(n). T(4) is a low impedance path for discharging C(1) to insure that the ramp always starts at the same voltage level.

The number of diodes n, equal to the number of increments required for the desired resolution in the digital data group, is connected between the output of the ramp generator and analog input transistor T(6). As the voltage on C(1) increases along the ramp, the Esaki diodes switch, one after another, so long as the ramp voltage exceeds the analog input. The effective voltage across the unswitched Esaki diodes is a function of the ramp voltage minus the analog input voltage, modified according to the ratio of switched to unswitched diodes. Diode E(1) switches at a first voltage, E(2) at a se...