Results 1  10
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39
From theory to practice: SubNyquist sampling of sparse wideband analog signals
 IEEE J. SEL. TOPICS SIGNAL PROCESS
, 2010
"... Conventional subNyquist sampling methods for analog signals exploit prior information about the spectral support. In this paper, we consider the challenging problem of blind subNyquist sampling of multiband signals, whose unknown frequency support occupies only a small portion of a wide spectrum. ..."
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Cited by 66 (38 self)
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Conventional subNyquist sampling methods for analog signals exploit prior information about the spectral support. In this paper, we consider the challenging problem of blind subNyquist sampling of multiband signals, whose unknown frequency support occupies only a small portion of a wide spectrum. Our primary design goals are efficient hardware implementation and low computational load on the supporting digital processing. We propose a system, named the modulated wideband converter, which first multiplies the analog signal by a bank of periodic waveforms. The product is then lowpass filtered and sampled uniformly at a low rate, which is orders of magnitude smaller than Nyquist. Perfect recovery from the proposed samples is achieved under certain necessary and sufficient conditions. We also develop a digital architecture, which allows either reconstruction of the analog input, or processing of any band of interest at a low rate, that is, without interpolating to the high Nyquist rate. Numerical simulations demonstrate many engineering aspects: robustness to noise and mismodeling, potential hardware simplifications, realtime performance for signals with timevarying support and stability to quantization effects. We compare our system with two previous approaches: periodic nonuniform sampling, which is bandwidth limited by existing hardware devices, and the random demodulator, which is restricted to discrete multitone signals and has a high computational load. In the broader context of Nyquist sampling, our scheme has the potential to break through the bandwidth barrier of stateoftheart analog conversion technologies such as interleaved converters.
Minimum rate sampling and reconstruction of signals with arbitrary frequency support
 IEEE Trans. Inform. Theory
, 1999
"... Abstract—We examine the question of reconstruction of signals from periodic nonuniform samples. This involves discarding samples from a uniformly sampled signal in some periodic fashion. We give a characterization of the signals that can be reconstructed at exactly the minimum rate once a nonuniform ..."
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Cited by 31 (0 self)
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Abstract—We examine the question of reconstruction of signals from periodic nonuniform samples. This involves discarding samples from a uniformly sampled signal in some periodic fashion. We give a characterization of the signals that can be reconstructed at exactly the minimum rate once a nonuniform sampling pattern has been fixed. We give an implicit characterization of the reconstruction system, and a design method by which the ideal reconstruction filters may be approximated. We demonstrate that for certain spectral supports the minimum rate can be approached or achieved using reconstruction schemes of much lower complexity than those arrived at by using spectral slicing, as in earlier work. Previous work on multiband signals have typically been those for which restrictive assumptions on the sizes and positions of the bands have been made, or where the minimum rate was approached asymptotically. We show that the class of multiband signals which can be reconstructed exactly is shown to be far larger than previously considered. When approaching the minimum rate, this freedom allows us, in certain cases to have a far less complex reconstruction system. Index Terms — Multiband, nonuniform, reconstruction, sampling. I.
Blind Adaptive Equalization of Mismatch Errors in Time Interleaved A/D Converter System
, 2003
"... To significantly increase the sampling rate of an A/D converter (ADC), a time interleaved ADC system is a good option. The drawback of a time interleaved ADC system is that the ADCs are not exactly identical due to errors in the manufacturing process. This means that time, gain and o#set mismatc ..."
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Cited by 20 (2 self)
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To significantly increase the sampling rate of an A/D converter (ADC), a time interleaved ADC system is a good option. The drawback of a time interleaved ADC system is that the ADCs are not exactly identical due to errors in the manufacturing process. This means that time, gain and o#set mismatch errors are introduced in the ADC system. These errors cause distortion in the sampled signal.
Calibration of sampletime error in a twochannel timeinterleaved analogtodigital converter
 IEEE TRANS. CIRCUITS SYST. I
, 2004
"... Offset mismatch, gain mismatch, and sampletime error between timeinterleaved channels limit the performance of timeinterleaved analogtodigital converters (ADCs). This paper focuses on the sampletime error. Techniques for correcting and detecting sampletime error in a twochannel ADC are desc ..."
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Cited by 18 (0 self)
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Offset mismatch, gain mismatch, and sampletime error between timeinterleaved channels limit the performance of timeinterleaved analogtodigital converters (ADCs). This paper focuses on the sampletime error. Techniques for correcting and detecting sampletime error in a twochannel ADC are described, and simulation results are presented.
The impact of combined channel mismatch effects in timeinterleaved ADCs
 IEEE Transactions on Instrumentation and Measurement
, 2005
"... converter (ADC) achieves high sampling rates with the drawback of additional distortions caused by channel mismatches. In this paper, we consider the dependency of the signaltonoiseanddistortion ratio (SINAD) on the combination of several different channel mismatch effects. By using either expli ..."
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Cited by 17 (10 self)
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converter (ADC) achieves high sampling rates with the drawback of additional distortions caused by channel mismatches. In this paper, we consider the dependency of the signaltonoiseanddistortion ratio (SINAD) on the combination of several different channel mismatch effects. By using either explicitly given mismatch parameters or given parameter distributions, we derive closedform equations for calculating the explicit or the expected SINAD for an arbitrary number of channels. Furthermore, we extend the explicit SINAD by the impact of timing jitter. We clarify how channel mismatches interact and perform a worst case analysis of the explicit SINAD for individual mismatch errors. We also show that equations describing the expected SINAD of individual mismatch errors are special cases of our general formulation. We indicate how to use the expected SINAD for finding efficient optimization priorities and demonstrate the importance of worst case analyses. Index Terms—Analogtodigital converter (ADC), channel mismatch, error analysis, signaltonoiseanddistortion ratio (SINAD), timeinterleaving, timing jitter.
An 8Bit 150MHz CMOS A/D Converter
, 1999
"... OF THE DISSERTATION An 8Bit 150MHz CMOS A/D Converter by YunTi Wang Doctor of Philosophy in Electrical Engineering University of California, Los Angeles, 1999 Professor Behzad Razavi, Chair Highspeed analogtodigital converters (ADCs) with resolutions of 8 bits find wide application in instrume ..."
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Cited by 13 (1 self)
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OF THE DISSERTATION An 8Bit 150MHz CMOS A/D Converter by YunTi Wang Doctor of Philosophy in Electrical Engineering University of California, Los Angeles, 1999 Professor Behzad Razavi, Chair Highspeed analogtodigital converters (ADCs) with resolutions of 8 bits find wide application in instrumentation and communication systems. For example, portable digital oscilloscopes use 8bit ADCs with sampling rates above one hundred megahertz. Also, the Gigabit Ethernet standard with CAT5 copper cable requires four 125MHz ADCs having a resolution of 7 to 8 bits to perform the frontend analogtodigital data conversion. This dissertation presents an 8bit, 5stage interleaved and pipelined ADC that performs analog processing only by means of openloop circuits such as differential pairs and source followers, thereby achieving a high conversion rate. The concept of "sliding interpolation" is proposed to obviate the need for a large number of comparators or interstage digitaltoanalog conve...
Reconstruction of twoperiodic nonuniformly sampled bandlimited signals using a discretetime differentiator and a timevarying multiplier
 IEEE Trans. Circuits Syst. II, Exp. Briefs
, 2007
"... Abstract—This brief considers the problem of reconstructing a bandlimited signal from its twoperiodic nonuniformly spaced samples. We propose a novel reconstruction system where a finiteimpulse response filter designed as differentiator followed by a timevarying multiplier recovers the uniformly ..."
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Cited by 7 (6 self)
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Abstract—This brief considers the problem of reconstructing a bandlimited signal from its twoperiodic nonuniformly spaced samples. We propose a novel reconstruction system where a finiteimpulse response filter designed as differentiator followed by a timevarying multiplier recovers the uniformly spaced from the nonuniformly spaced samples. The system roughly doubles the signaltonoise ratio with relatively few filter coefficients. The main advantage is that once the differentiator has been designed, it can be implemented with fixed multipliers, and only the coefficients of the timevarying multiplier have to be adapted when the sampling pattern changes; this reduces implementation costs substantially. In addition, the system allows an efficient polyphase implementation. Index Terms—Nonuniform sampling, timeinterleaved analogtodigital converter (TIADC), Taylor series expansion, Farrow
Blind Equalization of Time Errors in a Time Interleaved ADC System
"... To significantly increase the sampling rate of an A/D converter (ADC), a time interleaved ADC system is a good option. The drawback of a time interleaved ADC system is that the ADCs are not exactly identical due to errors in the manufacturing process. This means that time, gain and offset mismatch e ..."
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Cited by 7 (0 self)
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To significantly increase the sampling rate of an A/D converter (ADC), a time interleaved ADC system is a good option. The drawback of a time interleaved ADC system is that the ADCs are not exactly identical due to errors in the manufacturing process. This means that time, gain and offset mismatch errors are introduced in the ADC system. These errors cause distortion in the sampled signal. In this
Calibration of a Measurement System for High Frequency Nonlinear Devices
, 1995
"... The research work described in the thesis is situated in a broad technological context. It is explained what vectorial "nonlinear network" analyzers are and why they are needed. The importance of traceable calibrations is highlighted, in general as well as applied to the vectorial "no ..."
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Cited by 7 (6 self)
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The research work described in the thesis is situated in a broad technological context. It is explained what vectorial "nonlinear network" analyzers are and why they are needed. The importance of traceable calibrations is highlighted, in general as well as applied to the vectorial "nonlinear network" analyzer. Chapter 1 Introduction 2 1.1 Why do we need a measurement system for high frequency nonlinear devices? 1.1.1 Computing, prototyping and measuring We can talk and listen to people that are at a distance of ten thousand kilometers; day and night we can find out exactly where we are on sea as well as on land; we can watch a baseball game taking place seven thousand kilometers away; we can record whatever happens in our live and watch it ever after; we can see what happens inside our body without carving; we can listen to whatever music we want at any time, on any place; we can see beautiful pictures of planets three billion kilometers away; we can predict the weather it is goin...
Blind Estimation Of Timing Errors In Interleaved Ad Converters
 IN PROC. ICASSP 2001
, 2001
"... Parallel AD converter structures is one way to increase the sampling rate. Instead of increasing the sample rate in one AD converter, several AD converters with lower sampling rate can be used instead. A problem in these structures is that the time between samples is usually not equal because there ..."
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Cited by 7 (4 self)
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Parallel AD converter structures is one way to increase the sampling rate. Instead of increasing the sample rate in one AD converter, several AD converters with lower sampling rate can be used instead. A problem in these structures is that the time between samples is usually not equal because there are errors in the delays between the AD converters. We will here present a method to estimate the timing offset errors. The estimation algorithm works without any special calibration signal, instead the normal input signal is used. The only assumption that we need on the input signal is that most of the energy is concentrated to a low pass band, below about 1/3 of the Nyquist frequency. Simulations of the time interleaved AD converter show that the method estimates the errors with high accuracy.