Browse Prior Art Database

Differential Cascode Current Switch Direct Analog-To-Digital Converter

IP.com Disclosure Number: IPCOM000043233D
Original Publication Date: 1984-Aug-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Bustamante, CM: AUTHOR [+4]

Abstract

The method described uses differential cascode current switch (DCCS) technology to provide conversion of analog data into digital format. Of significance is the utilization of differential pair cells to perform the conversion function. The output of this direct analog-to- digital converter has the advantage of being time independent to produce digital signals that can be clocked either synchronously or asynchronously. Although there have been circuit chips designed to combine analog and digital data processing by designating a portion of the chip to handle the analog processing and leaving the rest of the chip to process the digital portion, this design integrates the analog data handling so that it can be placed anywhere on the chips. The analog input voltage (Vin), as shown in Fig.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 86% of the total text.

Page 1 of 2

Differential Cascode Current Switch Direct Analog-To-Digital Converter

The method described uses differential cascode current switch (DCCS) technology to provide conversion of analog data into digital format. Of significance is the utilization of differential pair cells to perform the conversion function. The output of this direct analog-to- digital converter has the advantage of being time independent to produce digital signals that can be clocked either synchronously or asynchronously. Although there have been circuit chips designed to combine analog and digital data processing by designating a portion of the chip to handle the analog processing and leaving the rest of the chip to process the digital portion, this design integrates the analog data handling so that it can be placed anywhere on the chips. The analog input voltage (Vin), as shown in Fig. 1, first is preprocessed into a form suitable to enter the DCCS analog-to- digital converter (ADC) circuit. Each voltage generator circuit splits the input voltage into three signals, each with its own voltage range. The outputs of one generator are complimentary to those of the other. The DCCS ADC uses the reference voltages and the voltage generator signals to selectively guide the current through one of eight output resistors so that each signal corresponds to a given analog input range. By using a single DCCS circuit with three levels of cascode differential pairs of transistors, as shown in Fig. 2, a resoluti...