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High Speed Analog to Digital Converter

IP.com Disclosure Number: IPCOM000089997D
Original Publication Date: 1969-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Dearden, ZT: AUTHOR

Abstract

The circuit is adaptable to full integration on a monolithic chip and completely eliminates the need for reactive elements, thus resulting in a high-speed analog-to-digital converter. The latter consists of eight identical threshold detecting circuits. In these the threshold of each Q3 transistor is determined by the relative position of the specific Q3 transistor base in the resistor chain, connected between V1 and V2, consisting of R2a...R2h. The voltage divider, consisting of resistors R2a...R2h and R5, develops a set of voltages at the base of the various Q3 transistors which differ by a quantum voltage Vq. Thus, the voltage at the base of Q3a is at some voltage Vba, the voltage at the base of Q3b is at Wba plus Vq, etc.

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High Speed Analog to Digital Converter

The circuit is adaptable to full integration on a monolithic chip and completely eliminates the need for reactive elements, thus resulting in a high-speed analog-to-digital converter.

The latter consists of eight identical threshold detecting circuits.

In these the threshold of each Q3 transistor is determined by the relative position of the specific Q3 transistor base in the resistor chain, connected between V1 and V2, consisting of R2a...R2h. The voltage divider, consisting of resistors R2a...R2h and R5, develops a set of voltages at the base of the various Q3 transistors which differ by a quantum voltage Vq. Thus, the voltage at the base of Q3a is at some voltage Vba, the voltage at the base of Q3b is at Wba plus Vq, etc. There are eight base reference voltages, thus allowing the circuit to resolve an input voltage with a continuous range of eight Vq volts into eight equal-amplitude portions.

Transistors Q2 and Q3 of each stage comprise a comparator. The difference between the voltage on the base of Q2 and the reference voltage on the base of Q3 determines whether current flows in the collector circuit of Q2 or Q3. Transistors Q1 in combination with resistors R1 serve to transfer a voltage to the Q2 base to allow conduction of all Q2 transistors below that which is part of the comparator combination that is referenced closest to the input voltage magnitude.

For example, if input voltage Ei slightly exceeds the voltage pre...