Columnparallel dual slope integrating adc pdf version. Adc dual slope integrator circuit a fascinating question has always been how can you convert an analog voltage to an equivalent digital word. A low power midrail dual slope analogtodigital converter for. As a minimum, each device contains the integrator, zero crossing comparator and proc essor interface logic. Dualslope adc architecture a dualslope adc dsadc integrates an unknown input voltage v in for a fixed amount of time t int, then deintegrates t deint using a known reference voltage v ref for a variable amount of time. A dualslope adc dsadc integrates an unknown input voltage v in for a fixed amount of time t int, then deintegrates t deint using a known reference voltage v ref for a variable amount of time see. Dual slope adcs are used in applications demanding high accuracy. An integrating adc in which the unknown signal is converted to a proportional time interval, which is then measured digitally. Pdf format this file type includes highresolution graphics and schematics when applicable.
However i this was so far the only place to find it. A dualslope adc dsadc integrates an unknown input voltage v. Both adcs make use of simple opamp circuits and control logic to do most of their work. This is a decided disadvantage because most real world signals require some smoothing. Although singleslopeintegratorswere used in early ads and voltmeters their dependence on an integrating capacitor for stability was considered an intolerable weakness. Adc dac converter analog to digital converter digital. Single slope analog todigital ad conversion by stephen ledford csic product engineering austin, texas introduction the most common implementation for analog todigital ad conversion among motorola microcontrollers is the successive approximation sar method. Singleslope analogtodigital ad conversion by stephen ledford csic product engineering austin, texas introduction the most common implementation for analogtodigital ad conversion among motorola microcontrollers is the successive approximation sar method.
A dual slope adc, on the other hand, averages together all the spikes and dips within the integration period, thus providing an output with greater noise immunity. Single slope analogtodigital ad conversion by stephen ledford csic product engineering austin, texas introduction the most common implementation for analogtodigital ad conversion among motorola microcontrollers is the successive approximation sar method. I have a project on doing simple dual slope adc using only our lab kit component. Pdf dual slope adc design from power, speed and area. In some countries this may not be legally possible. Columnparallel dualslope integrating adc pdf version. Unlike a dualslope,this converter has no inherent noise rejection capability. This article illustrates four techniques applied to the wellknown dual slope analog todigital converter adc in. The single and dualslope analog to digital converters. One of the many interesting architectures available is the dual slope integrator. So far, weve only been able to escape the sheer volume of components in the flash converter by using a dac as part of our adc circuitry. Successive approximation register type adc, sigma delta adc,dual slope integrating type adc etc. Dual slope adc using noninverting controlled bootstrap. Write the disadvantage of single slope integrator adc.
As we know adc is the short form of a to d converter. We explain why the slightly more complicated dualslope adc is generally a better choice of adc than the singleslope converter. Single slope adc architecture dual slope adc course hero. It is pretty slow, but its ability to reject highfrequency noise and fixed low frequencies such as. The dual slope adc dsadc is a type of analogtodigital conversion with low input bandwidths. The dualslope adc architecture was truly a breakthrough in adcs for high resolution applications such as digital voltmeters dvms, etc. Precise calibration of dualslope adcs application note maxim. The singleslope adc suffers the disadvantage of calibration drift. When compared to other types of adc techniques, the dual slope method is slow but is quite adequate for a digital voltmeter used for laboratory measurements. This adc circuit behaves very much like the digital ramp adc, except that the comparator reference voltage is a smooth sawtooth waveform rather than a stairstep. This page covers difference between various adc types including block diagram, equation etc. The charge on the capacitor at time t1 is proportional to the average value of vx times t1. Difference between adc typescounter,flash,sar,dual slope. This note explains the use of offset flipping for onthefly calibration of the adc.
Dual slope converter an integrating adc in which the. One of the many interesting architectures available is the dualslope integrator. Analog to digital conversion and digital to analog converter are described in this ppt. The dual slope adc is an analogtodigital converter that does its conversion using. Hank zumbahlen, with the engineering staff of analog devices, in linear circuit design handbook, 2008. Figure 2 shows a simple block diagram of this type of adcs11. Adc dac converter free download as powerpoint presentation. A video by jim pytel for renewable energy technology students at columbia gorge community college. Analogtodigital converters adcs translate analog signals into digital values for use in processing and control systems. This work has been released into the public domain by its author, scottr9 at english wikipedia.
This paper presents an interesting method using a dualslope analoguetodigital converter dsadc with high resolution to measure the rms value of the current, voltage, active power, and energy for linear and nonlinear loads. Adc converter technologies may occasionally convert a spike or dip because it captures the signal repeatedly at a single point in time. I would see this more as a first step to explain the multislope adc, not as a practical enhancement, that would be worth using. The accurate correspondence of this adcs output with its input is dependent on the voltage slope of the integrator. Slope integrating adc slope integrating adc the single slope adc suffers all the disadvantages of the digital ramp adc, with the added drawback of calibration drift.
Write the disadvantage of single slope integrator adc and. We now consider the single slope and the dual slope adcs. This is done by integrating the unknown for a predetermined length of time. An260a 20bit1 ppm linear slopeintegrating ad converter.
A columnparallel analogtodigital converter was designed for use with cmos active pixel sensors aps. Explain dual slope integration type adc with the help of a. As the name suggests, a dual slope adc produces an equivalent digital output for a corresponding analog input by using two dual slope technique. Dual slope integrating adc the input signal is applied to an integrator. The analog input signal is connected to the input terminal of a comparator that. Now the input is integrated for 300ms and the integrated value is 0. Dualslope adc architecture a dualslope adc dsadc integrates an unknown input voltage vin for a fixed amount of time tint, then deintegrates tdeint using a known reference voltage vref for a variable amount of time see figure 2. Analogtodigital converter design guide highperformance, standalone ad converters for a variety of embedded systems applications design ideas in this guide are based on many of microchips adc products.
Dual slope adc is the best example of an indirect type adc. Columnparallel singleslope adcs for cmos image sensors martijn snoeij, albert theuwissen, kofi makinwa and johan huijsing. The single slope adc suffers all the disadvantages. The advent of the dualslope converter see about integrating converters and capacitors solved the problem of integrating capacitor.
An example of sh circuit is given below the role of the capacitor is to be charged. Though the operation is quite slow, it has the ability to. An alternative ad conversion technique uses the singleslope ad converter. Introduction, basic dac techniques, weighted resistor dac, r2r ladder dac, inverted r2r dac, and ic 1408 dac, different types of adcs parallel comparator type adc, counter type adc, successive approximation adc and dual slope adc. Dual slope converter an integrating adc in which the unknown. Pdf the dualslope adc dsadc is a type of analogtodigital conversion with low input bandwidths. Another common adc is the dual slope converter, which relies on integration. An alternative ad conversion technique uses the single slope ad converter. If the output of the counter is a binary number, it will therefore be a binary representation of the input voltage. Precision analog front ends with dual slope adc microchip.
The dual slope integration type of ad conversion is a very popular method for digital voltmeter applications. Then a reference input is switched to the integrator, which integrates down from the level determined by the unknown until the starting level is reached. An analogtodigital converter, or adc, performs the former task while a digitaltoanalog converter, or dac, performs the latter. An integrating adc is a type of analogtodigital converter that converts an unknown input voltage into a digital representation through the use of an integrator. A dualslope adc, on the other hand, averages together all the spikes and dips within the integration period. So for a 2v full scale the lsb or the resolution is 1mv. The dualslope conversion improvement radojle radetic1, marijana pavlovkagadejev2, nikola milivojevic3 abstract. During the 2nd slope negative slope the input voltage is disconnected and the counter begins.
Analog to digital converter how adc works with pic mcu. It is pretty slow, but its ability to reject highfrequency noise and fixed low frequencies such as 50 hz or 60 hz makes it. Jan 26, 2018 dual slope or integrating type adc watch more videos at lecture by. A dualslope integration based analogtodigital convertor. With a dual slope adc you effectively get free averaging as the runup integration phase will have this effect. Integrating dual slope ad converter the ald500 series is alds newest family of monolithic cmos analog processor chips that implement precision, low power, low noise integrating dual slope ad converters having a resolution of 16, 17 and 18 bits, plus sign bit and overrange bit. The adaptation in the polarity of the input signal is achieved by exploiting a sign bit in the digital part of the topology. There are many types of analogtodigital converters adcs which can be classified according to the concept on which they were designed. Dual slope adc architecture a dual slope adc ds adc integrates an unknown input voltage v in for a fixed amount of time t int, then deintegrates t deint using a known reference voltage v ref for a variable amount of time. We now consider the singleslope and the dualslope adcs. There is a practical and common step in this direction, by having.
Our portfolio of adcs offers high speed devices with sampling speeds up to 10. The is the basic idea behind the socalled singleslope, or integrating adc. Measurement of active power, electrical energy, and trms. The conclusion of the study showed the efficiency of the dual slope adc as compared to other adcs, most especially the single slope adc keywords dual slope, adc, 8 bit, counter, cascaded 4 bit. A block diagram of the circuit figure 1 includes a single primary li cell, a millivoltoutput bridge sensor, a differential amplifier, and the dualslope adc, plus correction circuitry for offset, zero, and span. Dual slope adc design from power, speed and area perspectives conference paper pdf available april 2009 with 2,318 reads how we measure reads.
Request pdf dual slope adc using noninverting controlled bootstrap circuit this article presents the simple and inexpensive method to realize the dualslope analogtodigital converter adc. The tc500 is the base 16bit max device and requires both positive and negative power supplies. I walk through this in the video but if you want a chance to work through this handson you can download the. In the case of the adc, a digital representation of the analog voltage that is applied to the adcs input is outputted, the representation. If a filter was placed at the input substantial time lag due to settling requirements. This paper gives an overview of the development of columnparallel adcs that enable the highspeed, powerefficient readout of highresolution cmos imagers. May 05, 2016 i walk through this in the video but if you want a chance to work through this handson you can download the. Mar 22, 2014 the single slope analogtodigital converter ss adc is the most commonly used columnlevel adc for highspeed industrial, complementary metaloxide semiconductor cmosbased xray image sensors because of its small chip area the width of a pixel, its simple circuit structure, and its low power consumption. In its basic implementation, the dual slope converter, the unknown input voltage is applied to the input of the integrator and allowed to ramp for a fixed time period the runup period. A dualslope adc, on the other hand, averages together all the spikes and dips within the integration period, thus providing an output with greater noise immunity.
Integrating adc overview aka ramp and slope adc different flavors, e. Ccjrootv8n5pdf group 4 general pathology, logic and cytologic techniques free download as pdf file. In this thesis, a novel low power analogtodigital converter adc for the digitization and analyzation of the. A dualslope integration based analog todigital convertor hasan krad department of computer science and engineering, college of engineering, qatar university, p.
The ex input signal is directly coupled to the comparator input with no filtering. A fascinating question has always been how can you convert an analog voltage to an equivalent digital word. Today, almost every electronic product contains an analogtodigital converter. To overcome this sensitivity to the component values, the dualslope integrating architecture is used. The output is also extremely simple, just a pulse that needs to be timed which can be done with even the simplest micro controllers.
The singleslope analogtodigital converter ssadc is the most commonly used columnlevel adc for highspeed industrial, complementary metaloxide semiconductor cmosbased xray image sensors because of its small chip area the width of a pixel, its simple circuit structure, and its low power consumption. Write the disadvantage of single slope integrator adc and how does dual slope integrator adc overcome this problem. This analogtodigital converter adc has been at the heart of the digital volt meter. As shown in figures 410a and 410b, the voltage to be measured v x is input to an integrator, charging the capacitor for a fixed time interval t 1, which corresponds to a certain number of clock cycles. We use quasisynchronous sampling with the rst harmonic of the voltage network. During the first slope positive slope the sampling time is a fixed value and therefore the duration gives no clue about what the input voltage is. The higher the input voltage, the greater the magnitude of the voltage stored on the integrator during this phase. In its basic implementation, the dualslope converter, the unknown input voltage is applied to the input of the integrator and allowed to ramp for a fixed time period the runup period. This paper presents the design of an adjustable 14bit dual slope adc with wide input range for low frequency applications. We explain why the slightly more complicated dual slope adc is generally a better choice of adc than the single slope converter. Feb 24, 2014 a video by jim pytel for renewable energy technology students at columbia gorge community college. But the problem is i cant not come up with any ideas to make switch from v in and vref controlled by my kits which is included only basic transistors 2en3904,jfet,and some ic like 7474,7485,lm324,counter ls191,bcd display.
The proposed topology can handle both negative and positive input voltage signal with high accuracy. Pdf the dualslope conversion improvement researchgate. Dual slope adc architecture a dual slope adc ds adc integrates an unknown input voltage vin for a fixed amount of time tint, then deintegrates tdeint using a known reference voltage vref for a variable amount of time see figure 2. Single slope adc architecture dual slope adc architecture. This paper presents an interesting method using a dual slope analoguetodigital converter ds adc with high resolution to measure the rms value of the current, voltage, active power, and energy for linear and nonlinear loads. I found a reference to the enhanced dualslope in the 2nd reference hp journal, 40 2. A block diagram of the circuit figure 1 includes a single primary li cell, a millivoltoutput bridge sensor, a differential amplifier, and the dual slope adc, plus correction circuitry for offset, zero, and span. The dualslope adc dsadc is a type of analogtodigital conversion with low input bandwidths.
It covers counter type adc,parallel comparator flash adc, sarsuccessive approximation register type adc,sigma delta adc, dual slope integrating type adc etc. With the advent of the advanced technology and the need for more. The dual slope adc is an analogtodigital converter that does its conversion using quite low bandwidth as its input. A single adc cell no control or bias circuitry objectives. A complete device list and corresponding data sheets or these products can be found at. Scottr9 grants anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law. The peak value attained contains the only clue but that is unknown to this type of adc. Sep 26, 2019 introduction, basic dac techniques, weighted resistor dac, r2r ladder dac, inverted r2r dac, and ic 1408 dac, different types of adcs parallel comparator type adc, counter type adc, successive approximation adc and dual slope adc. Whats the difference between sar and deltasigma adcs. Therefore, the columnparallel single slope architecture fig.
These adcs are integrating type adc, meaning that they use the integrator for the. An adaptable 14bit dual slope adc with wide input range. Now the input is integrated for 300ms and the integrated. Precise calibration of dualslope adcs application note. The dual slope adc architecture was truly a breakthrough in adcs for high resolution applications such as digital voltmeters dvms, etc. Slope integrating adc slope integrating adc the singleslope adc suffers all the disadvantages of the digital ramp adc.
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