V. R. GAIKWAD

Dual Slope Analog to Digital Converter

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Block Diagram

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Circuit Diagram

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Time Domain Analysis

tV

TV

RCTV

RCtVtv

RCTV

RCtV

tv

VvTvvRCTVTv

TtVvv

vdvRC

tv

inref

inref

o

inrefo

refio

ino

ini

t

io

0)(

)(

;);()0(

)(

;;0)0(

)0(1)(0

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Reflection Spot

What is the resolution of 3 ½ digit DVM which can measure input voltage from 0 V to 2 V

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Example

Specifications Maximum input voltage

Vin =2 V 3 ½ digit display Measurement Cycles per

second (Sampling frequency) fs=25 Hz

Design Measurement interval

Ts =1/ fs=40 ms Integration duration of

Vin T = Ts / 2=20 ms Integration duration of

Vref ; tmax = T / 2=10 ms Vref= -VinmaxT/ tmax=-4 V For N clock cycles in

time interval tmax; clock required is fclk=N/ tmax=200 kHz

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Reference

Design with Operational Amplifier and Analog Integrated Circuit By Sergio Franco

Modern Digital Electronics By R. P. Jain

Introduction to System design using Integrated Circuit By B. S. Sonde

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