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27
Spectral Shaping of Circuit Errors in DigitaltoAnalog Converters
, 1997
"... Recently, various multibit noiseshaping digitaltoanalog converters (DAC's) have been proposed that use digital signal processing techniques to cause the DAC noise arising from analog component mismatches to be spectrally shaped. Such DAC's have the potential to significantly increase the present p ..."
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Cited by 43 (19 self)
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Recently, various multibit noiseshaping digitaltoanalog converters (DAC's) have been proposed that use digital signal processing techniques to cause the DAC noise arising from analog component mismatches to be spectrally shaped. Such DAC's have the potential to significantly increase the present precision limits of 16 data converters by eliminating the need for onebit quantization in deltasigma modulators. This paper extends the practicality of the noiseshaping DAC approach by presenting a general noiseshaping DAC architecture along with two specialcase configurations that achieve first and secondorder noiseshaping, respectively. The secondorder DAC configuration, in particular, is the least complex of those currently known to the author. Additionally, the paper provides a rigorous explanation of the apparent paradox of how the DAC noise can be spectrally shaped even though the sources of the DAC noisethe errors introduced by the analog circuitryare not known to the ...
On the Stability of Sigma Delta Modulators
 IEEE TRANSACTLONS ON SIGNAL PROCESSING, VOL. 41. NO. 7. JULY 1993
, 1993
"... In this paper we propose a framework for stability analysis of EA modulators, and argue that limit cycles for constant inputs are natural objects to investigate in this context. We present a number of analytical and approximate techniques to aid the stability analysis of the double loop and interpol ..."
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Cited by 15 (2 self)
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In this paper we propose a framework for stability analysis of EA modulators, and argue that limit cycles for constant inputs are natural objects to investigate in this context. We present a number of analytical and approximate techniques to aid the stability analysis of the double loop and interpolative modulators, and use these techniques to propose ways of improved design that explicitly take stability into account.
TimeInterleaved Oversampling A/D Converters: Theory and Practice
 IEEE Trans. Circuits Syst. II
, 1997
"... In this paper, the design procedure and practical issues regarding the realization of timeinterleaved oversampling converters are presented. Using the concept of block digital filtering, it is shown that arbitrary 16 topologies can be converted into corresponding timeinterleaved structures. Prac ..."
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Cited by 14 (3 self)
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In this paper, the design procedure and practical issues regarding the realization of timeinterleaved oversampling converters are presented. Using the concept of block digital filtering, it is shown that arbitrary 16 topologies can be converted into corresponding timeinterleaved structures. Practical issues such as finite opamp gain, mismatching, and dc offsets are addressed, analyzed, and practical solutions to overcome some of these problems are discussed. To verify the theoretical results, a discretecomponent prototype of a secondorder timeinterleaved 16 analog/digital (A/D) converter has been implemented and the design details as well as experimental results are presented. Index TermsConverters, timeinterleaved, oversampling. I. INTRODUCTION O VERSAMPLING converters have become a popular technique for data conversion [1]. One reason for their popularity is their outstanding linearity which comes from the fact that they usually exploit a 1b quantizer. Even with a tr...
Reconstruction of oversampled bandlimited signals from sigma delta encoded binary sequences
 IEEE Transactions on Signal Processing
, 1994
"... AbstractWe consider the application of EA modulators to analogtodigital conversion. We have previously shown that for constant input signals, optimal nonlinear decoding can achieve large gains in signaltonoise ratio (SNR) over linear decoding. In this paper we show a similar result for bandlimi ..."
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Cited by 11 (1 self)
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AbstractWe consider the application of EA modulators to analogtodigital conversion. We have previously shown that for constant input signals, optimal nonlinear decoding can achieve large gains in signaltonoise ratio (SNR) over linear decoding. In this paper we show a similar result for bandlimited input signals. The new nonlinear decoding algorithm is based on projections onto convex sets (POCS), and alternates between a timedomain operation and a band limitation to find a signal invariant under both. The timedomain operation results in a quadratic programming problem. The band limitation can be based on singular value decomposition of a certain matrix. We show simulation results for the SNR.performance of a POCSbased decoder and a linear decoder for the single loop, double loop and twostage CA modulators and for a specific fourthorder interpolative modulator. Depending on the modulator and the oversampling ratio, improvements in SNR of up to 1&20 dB can be achieved. I.
New properties of sigmadelta modulators with dc inputs
 Communications, IEEE Transactions on
, 1992
"... AbstractWe derive new properties of the single and doubleloop sigmadelta modulators with constant inputs, by exploiting the inherent structure of the output sequences or codewords that the modulators are capable of producing. Specifically, we first derive upper bounds of O(.Y2) and O(Y3) on the ..."
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Cited by 8 (2 self)
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AbstractWe derive new properties of the single and doubleloop sigmadelta modulators with constant inputs, by exploiting the inherent structure of the output sequences or codewords that the modulators are capable of producing. Specifically, we first derive upper bounds of O(.Y2) and O(Y3) on the number of rbit codewords for the single and doubleloop modulators, respectively. We then derive analytical lower bounds on the mean squared error (MSE) obtainable by any decoder, linear or nonlinear, in approximating the constant input; based on.Ybit codewords, the bounds are O(.Y3) and O(AT6) for the single and doubleloop modulators, respectively. Optimal nonlinear decoders for constant inputs can be based on a table lookup approach which operates directly on the nonuniform quantization intervals. Numerical results show that if the constant input is uniformly distributed, the MSE of such nonlinear decoders are 0(?*3) and O(S’) for the single and doubleloop modulators, respectively. Using simulations we find that the optimal nonlinear decoders perform better than linear decoders, by about 3 and 20 dB for the single and doubleloop modulators, respectively. We also introduce a cascade structure specifically for constant inputs, and derive its corresponding decoding algorithm. The idea behind the cascade structure is to requantize the residue from each stage in order to fully utilize the dynamic range of the next stage. We show that for a fixed latency, the MSE performance of our cascade structure is 12 dB superior, and its throughput is twice the conventional twostage MASH modulator. I.
Deterministic Analysis of Oversampled A/D Conversion and Sigma/Delta Modulation, and Decoding Improvements using Consistent Estimates
, 1993
"... Analogtodigital conversion (ADC) which consists in a double discretization of an analog signal in time and in amplitude is increasingly used in modern data acquisition. However, the conversion process always implies some loss of information due to amplitude quantization. Oversampling is the techni ..."
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Cited by 6 (0 self)
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Analogtodigital conversion (ADC) which consists in a double discretization of an analog signal in time and in amplitude is increasingly used in modern data acquisition. However, the conversion process always implies some loss of information due to amplitude quantization. Oversampling is the technique currently used to reduce this loss of accuracy. The error reduction can be performed by lowpass filtering the quantized signal, thus eliminating the high frequency components of the quantization error signal. This is the classical method used to reconstruct the analog signal from its oversampled and quantized version. This reconstruction scheme yields a mean squared error (MSE) inversely proportional to the oversampling ratio R. The fundamental question pursued in this thesis is the following: how much information is available in the oversampled and quantized version of a bandlimited signal for its reconstruction? In order to identify this information, it is essential to go back to the original description of quantization which is typically deterministic. We show that a reconstruction scheme fully takes this information into account
MLattice: A System For Signal Synthesis And Processing Based On ReactionDiffusion
 PROCESSING BASED ON REACTIONDIFFUSION. SCD THESIS, MIT
, 1994
"... This research begins with reactiondiffusion, first proposed by Alan Turing in 1952 to account for morphogenesis  the formation of hydranth tentacles, leopard spots, zebra stripes, etc. Reactiondiffusion systems have been researched primarily by biologists working on theories of natural pattern f ..."
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Cited by 5 (3 self)
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This research begins with reactiondiffusion, first proposed by Alan Turing in 1952 to account for morphogenesis  the formation of hydranth tentacles, leopard spots, zebra stripes, etc. Reactiondiffusion systems have been researched primarily by biologists working on theories of natural pattern formation and by chemists modeling dynamics of oscillating reactions. The past few years have seen a new interest in reactiondiffusion spring up within the computer graphics and image processing communities. However, reactiondiffusion systems are generally unbounded, making them impractical for many applications. In this thesis we introduce a bounded and more flexible nonlinear system, the "Mlattice", which preserves the natural patternformation properties of reactiondiffusion. On the theoretical front, we establish relationships between reactiondiffusion systems and paradigms in linear systems theory and certain types of artificial "neurallyinspired" systems. The Mlattice is closel...
DeltaSigma Data Conversion in Wireless Transceivers
, 2002
"... Highperformance analogtodigital converters, digitaltoanalog converters, and fractional frequency synthesizers based on deltasigma (16) modulationcollectively referred to as data convertershave contributed significantly to the high level of integration seen in recent commercial wirel ..."
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Cited by 4 (2 self)
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Highperformance analogtodigital converters, digitaltoanalog converters, and fractional frequency synthesizers based on deltasigma (16) modulationcollectively referred to as data convertershave contributed significantly to the high level of integration seen in recent commercial wireless handset transceivers. This paper presents a tutorial on data converters and their uses and implications with respect to wireless transceiver architectures.
0 Systematic Approach for Scaling Coefficients of DiscreteTime and ContinuousTime SigmaDelta Modulators
"... —In this paper we present a systematic method to scale the integrators output swings of modulator. It is shown that this scaling method preserves both the Noise Transfer Function and the Signal Transfer Function of the modulator. Examples are given to illustrate the effectiveness of the proposed met ..."
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Cited by 3 (3 self)
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—In this paper we present a systematic method to scale the integrators output swings of modulator. It is shown that this scaling method preserves both the Noise Transfer Function and the Signal Transfer Function of the modulator. Examples are given to illustrate the effectiveness of the proposed method to alleviate circuit nonidealities.
A Low Oversampling Ratio 14b 500kHz ADC with a SelfCalibrated Multibit DAC
 IEEE J. SolidState Circuits
, 1996
"... Abstract — Deltasigma (16) analogtodigital converters (ADC’s) rely on oversampling to achieve highresolution. By applying multibit quantization to overcom stability limitations, a circuit topology with greatly reduced oversampling requirements is developed. A 14bit 500kHz 16 ADC is described t ..."
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Cited by 3 (0 self)
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Abstract — Deltasigma (16) analogtodigital converters (ADC’s) rely on oversampling to achieve highresolution. By applying multibit quantization to overcom stability limitations, a circuit topology with greatly reduced oversampling requirements is developed. A 14bit 500kHz 16 ADC is described that uses an oversampling ratio of only 16. A fourthorder embedded modulator, fourbit quantizer, and selfcalibrated digitaltoanalog converter (DAC) are used to achieve this performance. Although the highorder embedded architecture was previously thought to be unstable, it is shown that with proper design, a robust system can be obtained. Circuit design and implementation in a 1.2"m CMOS process are presented. Experimental results give a dynamic range of 84 dB with a sampling rate of 8 MHz and oversampling ratio of 16. This is the lowest oversampling ratio for this resolution and bandwidth achieved to date. I.