User:Sandaranghe

Introduction

 * An integrating ADC is a type of analog-to-digital converter that converts an unknown input voltage into a digital representation through the use of an integrator.
 * Integrating analog-to-digital converters (ADCs) provide high resolution analog-to-digital conversions, with good noise rejection. Basically there are 3 types of  Integrating ADCs.
 * 1) Single-Slope Integrating ADC
 * 2) Dual-Slope Integrating ADC
 * 3) Multi-Slope Integrating ADC

Single-Slope INTEGRATING ADC
The simplest form of an integrating ADC is the single-slope architecture In this architecture the input voltage is integrated and the value compared against a known reference value. Major drawback- Accuracy is dependent on the tolerances of the integrator's R and C values. To overcome this matter The Dual-Slope Integrating ADC is introduced

operation

 * The analog switch first connects Vin to the integrator
 * The integrator starts generating the saw tooth waveform
 * The switch position will remain set at Vin during a fixed number of clock cycles
 * Analog switch moves its position to allow –Vref to enter the integrator
 * –Vref is a negative voltage, the saw tooth waveform goes towards zero, using a number of clock cycles proportional of the Vin value

A dual-slope ADC integrates an unknown input voltage (VIN) for a fixed amount of time (TINT), then "de-integrates" (TDEINT) using a known reference voltage (VREF) for a variable amount of time

The key advantage of this architecture over the single-slope is that the final conversion result is insensitive to errors in the component values. That is, any error introduced by a component value during the integrate cycle will be cancelled out during the de-integrate phase.

In equation form:

TDEINT = TINT × (VIN / VREF)

From this equation, we see that the de-integrate time is proportional to the ratio of VIN / VREF

Advantages

 * 1) Providing an output with greater noise immunity
 * 2) Averages together all the spikes and dips in the signal within the integration period
 * 3) Escapes the calibration drift problem of the single-slope ADC
 * 4) Easy to obtain good resolution

Limitations

 * 1) Limits to maximum resolution by the accuracy of the comparator and the quality of the integrator's capacitor


 * 1) Low speed

Applications
Dual-slope ADCs are used in applications demanding high accuracy.


 * DPM (Digital Panel Meter)


 * DMM(Digital Multi Meter)

Multi-Slope Integrating ADCs
The normal limit for resolution of the dual-slope architecture is based on the speed of the error comparator

Multi-Slope Integrating ADC has a small slew rate, so the error comparator would allow the integrator to go well beyond its trip point by a considerable amount