Behavioral model of pipeline adc by using simulinkr. A 1bit adc as a changeover switch is a 1 bit dac, so a comparator is a 1 bit adc see figure 1. For the flash adc, the concept of 2x interpolation to. Improving accuracy and energy efficiency of pipeline analog. The adc uses opamp sharing techniques which are shared between amplifying and mdac stage. Design of highperformance pipeline analogtodigital converters in lowvoltage processes sobhan sofimowloodi and syyed mohammad alavi electrical department, imam hussein university, tehran, iran corresponding author. Successive approximation adcs typically have 12 to 16 bit resolution, and their sampling rates range from 10 ksamplessec to 10 msamplessec. A comparison of result is illustrated, between the ideal 14 bit adc behavior model and the 14 bit pipeline adc with nonidealities. This architecture consists of two singlebit secondorder deltasigma modulators in the first and second stages and a pipeline adc. Although the pipeline architecture can achieve very high frequency opera.
Design of highperformance pipeline analogto digital. Fine adcs full scale range needs to span only 1 lsb of coarse. Many of us consider the adc to be a mysterious device. Simulink behavioral modeling of a 10bit pipelined adc. Bibhudatta sahoo university of illinois at urbanachampaign. Data converters, analog to digital converter adc and digital to analog converter dac, play a fundamental role. This type of adc is generally referred to as subranging because the input range is subdivided into a number of smaller ranges subranges which are, in turn, further subdivided. You will need to know if precision is important in your application, and if you might want a sampleandhold feature. An analogtodigital converter adc is a critical block of the sensing unit of all implants and for. The basic idea behind the pipeline adc is that each stage will first sample and hold the input then compare this to vref2. In a pipelined adc with bbits of resolution, a maximum capacitor mismatch of 12bi is allowable in each of the ith. The maximum dynamic range of the pipeline adc is determined at least partly by the thermal noise at the input of the converter, including the ktc noise of the input sampling capacitor.
Introduction this adc is designed to convert of pixels analogic value to digital value in the my image cmos sensor design. The adc was designed for use in a split adc architecture for calibration. Challenges of the pipeline adc as nationals highspeed adc products demonstrate, the pipeline adc is clearly capable of providing high dynamic performance at sampling rates up to 200 msps. Correction for capacitor mismatch we assumed that capacitances would have a gaussian distribution centered at the specified value with a standard deviation given by 0.
Abcs of adcs analogtodigital converter basics nicholas gray data conversion systems staff applications engineer november 24, 2003. This work aims to improve the accuracy and energy efficiency of the pipeline architecture by combining it with more accurate or more energy efficient architectures such as sigmadelta and successiveapproximation sar. The minimum setup and hold time provided by adc needs to be accepted by the fpga to properly capture the data. Detailed knowledge of the behavior in a system allows the adc design margin to be minimized thus saving cost and power consumption. A 10 bit opampsharing pipeline analogtodigital converter adc using a novel mirror telescopic operational amplifiers opamp with dual nmos differential inputs is presented. Abstract a 10bit pipeline analogtodigital converter adc is designed using switched capacitor circuit. If the input is greater than v ref 2, output a 1 for that stage and pass the input voltage directly to the next stage. This tutorial begins with a brief discussion of the comparator which is the basic building block for flash converters. Typically pipeline adc noise dominated by inter stage gain blocks sub adc comparator noise translates into comparator threshold uncertainty and is compensated for by redundancy v in stage 1 stage 2 stage 3 v n1 v n2 n3 v in g1 g2 g3 22 in 2 n2 n3 noise n1 2 2 2 vv. This paper will explain how the sar adc operates by using a binary search algorithm to converge on the input signal. A 10bit, 200mss cmos pipeline adc using new shared opamp. Throughput increased to as high as one sample per clock cycle. Tutorial 1023 understanding pipelined adcs oct 02, 2001. This paper presents the advantage of behavior model.
Pipeline adc concurrent stage operation stages operate on the input signal like a shift register new output data every clock cycle, but each stage. Tutorial mt020 was needed to meet the adc requirement, as the solidstate coder based on waldhaurs patent did not have the necessary accuracy at the higher sampling rates. Various power reduction techniques have been developed for pipelined adcs, such as gain calibration for the sample and hold amplifier, flash adcbased msb. Pipelined adc design a tutorial based on slides from dr. This design builds on previous work that uses a split adc architecture on a design with non linear gain and. Pdf pipeline analogtodigital converters with radix pipeline analogtodigital converters is conducted.
Solve rfams design challenges using the cadence virtuoso. First, the input signal vin is captured by the sample and. The analogtodigital converter adc is a key component in digital communications receive channels, and the correct choice of adc is critical for optimizing system design. Design and implementation a 8 bits pipeline analog to. The fundamental operating principles of these three architectures are described. Recent design improvements have extended the sampling frequency of these adcs into the megahertz region with 18bit resolution. In this episode shahriar explores the world of deltasigma modulators with emphasis on a deltasigma analog to digital converter adc. Pipeline adc is a mixedsignal system, which consists of sample and hold amplifier sha, subadc, multiplying digitaltoanalog converter mdac and. A 14bit pipeline adc behavior model using veriloga for.
Pipeline adc enhancement techniques computer engineering. The goal from adc design is to run in the video rate and it must have small size in the layout design. Typically pipeline adc noise dominated by inter stage gain blocks subadc comparator noise translates into comparator threshold uncertainty and is compensated for by redundancy v in stage 1 stage 2 stage 3 v n1 v n2 n3 v in g1 g2 g3 22 in 2 n2 n3 noise n1 2 2 2 vv. Using the avr xmega adc introduction the microchip avr xmega adc module is a highperformance analogtodigital converter capable of conversion rates up to 2 million samples per second msps with a resolution of 12 bits. In this article, we discuss what design factors drive the selection of the adc, how to specify the adc and when to choose between a pipeline adc and a sigmadelta. Pipeline adcs come of age tutorial maxim integrated. The first commercial adc using waldhaurs gray code architecture was the 8bit, 10msps hs810 from computer labs, inc. Pipeline adc with a nonlinear gain stage and digital correction. In the mid 1970s, a new data converter architecture was introduced to the analog and. C jv os c p in general has little effect on the conversion v x0 at the end of the search however, v x is always attenuated due to charge sharing of c p binary search is sensitive to intermediate errors made during search. In any event, the chosen adc must be given enough time to sample the signal, and sampling time can be affected by the signal sources impedance going into the adc. It can, however, be considered very simply to be the instrument that it is. Introduction 8 to 10bit resolution with a conversion speed of hundreds of mega samples per second adcs are widely used in wireless communication system.
In the work included in this thesis an accurate model of a successiveapproximation adc is developed. The second technique develops a new mdac topology which enables a pipelined adc to be designed without a frontend sampleandhold, and thus allows for. A pipelined adc, however, generally requires significantly more silicon area than an equivalent sar. The implication is that none of the flash adcs in figure 1 has to be as accurate as the entire adc. Pipeline adc design the pipeline adc architecture combines the benefits of high throughput and an input capacitance bound by noise constraints. The pipeline adc will work at the higher speeds and higher bandwidth than the. The pipeline adc is a popular architecture for implementing adcs with a wide range of speed and resolution. Design and evaluate successive approximation adc using. Typically pipeline adc noise dominated by inter stage gain blocks subadc comparator noise translates into comparator threshold uncertainty and is compensated for by redundancy. The pipeline adc will work at the higher speeds and. If the input is greater than vref2, output a 1 for that stage and pass the input voltage directly to. This subranging adc can best be analyzed by examining the residue waveform at the input to the secondstage adc as shown in figure 2.
Finally, the article will contrast the sar architecture with pipeline, flash, and sigmadelta adcs. The successive approximation adc has been the mainstay of data acquisition systems for many years. Devicelevel modeling and synthesis of highperformance. Comparator metastability in a flash can lead to sparklecode errors, a condition in which the adc provides unpredictable, erratic conversion results. Features of the adc were simulated in matlab to test and examine its basic functionality.
On the design of a 220 mash deltasigmapipeline modulator. For the love of physics walter lewin may 16, 2011 duration. A 14 bit pipeline adc is constructed with simulation of behavior model and the noise model. This successive approximation register sar adc model demonstrates a 12 bit converter with a circuitlevel dac model. The pipeline adc topology is suitable for those target specifications. Butterfield boise state university december 15, 2011 1. A userfriendly adc simulator for courses on analog.
Benefits and drawbacks of this method are evaluated with respect to calibration and circuit complexity. The tutorial begins with a brief introduction to the history and definition of a digital image sensor, as well as converter characteristics, before addressing dac and adc architectures. Although the flash allparallel architecture see tutorial mt020 dominated the 8bit video ic adc market in the 1980s and early 1990s, the pipelined architecture has largely replaced the flash adc in modern applications. Pipelined adc analog to digital converter digital to. A pipeline adc is typically less susceptible to comparator metastability.
Pdf basic block of pipelined adc design requirements. This research presents a highresolution pipeline adc in lowvoltage processes. In this schematic, the analog input, vin, is first sampled and held steady by a sampleandhold. Sar adc is that at the end of the conversion time, the data corresponding to the sampling clock edge is available with no pipeline delay. Chapter 16 pipeline and sar adcs for advanced nodes. This paper discusses the design of a 16bit 10mhz pipeline analog to digital converter adc using the split adc architecture. The specific topic of interest of this paper is methods of improving adc accuracy. The inner structure of a pipeline stage comprises of four blocks, as illustrated in fig. The goal of this work was to design a pipeline analog to digital converter that can be calibrated and corrected in the digital domain. A sar also displays a latency of only one cycle one cycle 1f sample, versus about three or more cycles in a typical pipeline adc. Design and implementation a 8 bits pipeline analog to digital. Because the analogtodigital converter ad converter or adc has both analog and digital functions, it is a mixedsignal device. In this paper, a 220 mash deltasigma modulator is presented. The ideal ad converter adc produces a digital output code that is a function of the analog input voltage and the voltage reference input.
This book presents models and procedures to design pipeline analogtodigital converters, compensating for device inaccuracies, so that highperformance specs can be met within short design cycles. The datasheets of the adc and fpga have the setup and hold time numbers for a specific sampling rate. In this schematic, the analog input, vin, is first sampled and held steady by a sample andhold. Haze, basic block of pipelined adc design requirements basic block of pipelined adc design requirements vilem kledrowetz, jiri haze dept. Reduction of power and area is achieved by completely merging the frontend sampleandhold ampli. In this article, we discuss what design factors drive the selection of the adc, how to specify the adc and when to choose between a pipeline adc and a sigmadelta adc. Pipelined adc free download as powerpoint presentation.
Keywords analogtodigital converter pipeline adc highswing ampli. Later chapters cover pipeline adc designs, digital correction, calibration, and testing according to ieee standards. It also explains the heart of the sar adc, the capacitive dac, and the highspeed comparator. Boser, a 12b, 75mss pipelined adc using openloop residue. The figure below shows the basic adc measurement circuit. As with a pipeline, a sar with more than 12 bits of accuracy usually requires some form of trimming or. Why use oversampling when undersampling can do the job. Aug 03, 2014 in this episode shahriar explores the world of deltasigma modulators with emphasis on a deltasigma analog to digital converter adc. Each stage performs an operation on the signal, provides the output for the following sampler, and. Ee247 lecture 23 university of california, berkeley. Feb 16, 2017 this feature is not available right now. Page 21 measurement results 12bit adc w extra 2bits for calibration. This white paper presents a new method to address these challenges by applying.
This type of device takes a binary code that could have been encoded by an analog to digital converter, and turns it back into an analog voltage. Design and simulation of 10bit pipeline adc using switch. A system and circuit level design of each component of the adc was created in cadence. Adc1 control register 1 this register controls the basic operation of the adc module, including behavior in sleep and idle modes, and data formatting.
Typical pipeline architecture is illustrated in figure 3. If the input is above a threshold, the output has one logic value, below it has another. Maxim design support technical documents tutorials ad and da conversionsampling circuits app 1023 maxim design support technical documents tutorials basestationswireless infrastructure app 1023 keywords. Pipeline adc concurrent stage operation stages operate on the input signal like a shift register new output data every clock cycle, but each stage introduces at least. Large adc input capacitance since depending on input voltage level different number of comparator input transistors would be onoff total input capacitance varies as input varies.
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