Analog-to-digital 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

This research begins with reaction-diffusion, first proposed by Alan Turing in 1952 to account for morphogenesis -- the formation of hydranth tentacles, leopard spots, zebra stripes, etc. Reaction-diffusion 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 reaction-diffusion spring up within the computer graphics and image processing communities. However, reaction-diffusion systems are generally unbounded, making them impractical for many applications. In this thesis we introduce a bounded and more flexible non-linear system, the "M-lattice", which preserves the natural pattern-formation properties of reaction-diffusion. On the theoretical front, we establish relationships between reaction-diffusion systems and paradigms in linear systems theory and certain types of artificial "neurally-inspired" systems. The M-lattice is closel...

Recent efforts in the design of wireless RF transceivers focus on high integration and multi-standard operation. Higher integration can be obtained by using receiver architectures, such as wide-band IF with double conversion (WIF), that perform channel select filtering on-chip at baseband. Performing this baseband channel select filtering in the digital domain allows for the programmability necessary to adapt to the different channel bandwidths, sampling rates, and CNR requirements of multiple communication standards. At the back of a wide-dynamic range sigma-delta modulator, a decimation filter can select a desired channel in the presence of both strong adjacent channel interferers and quantization noise from the digitization process. A low-power decimation filter that performs channel select filtering for the GSM (European cellular) and DECT (European cordless) standards is presented. Automatic gain control is used within the filter to reduce the dynamic range and power consumption. Since the two standards have different blocking profiles and CNR i

This paper presents an architecture for multi-mode terminals, strictly speaking multi-mode receivers, exploiting IF sampling with Sigma-Delta ADCs. It is shown that Sigma-Delta ADCs are not only an efficient means of digitizing signals but are a nearly perfect fit to the task of analog-to-digital conversion in multi-mode terminals. For further processing the digitized signal, i.e. channel filtering for FDMA systems as well as decorrelation for spread-spectrum systems, a common hardware is presented.

The technology to build highly integrated 3-dimensional computational image sensors by stacking and interconnecting layers of 2-dimensional silicon ICs is being developed. Unlike multi-chip module (MCM-V) packaging, in which interconnect lines are brought to the periphery of a chip stack to achieve vertical integration, this new technology allows virtually unrestricted placement of vertical vias within the interior of the chip. The goal of this development is to enable high speed, high resolution image processing in compact low power wearable systems that would be coupled with a head-mounted display (HMD). Potential applications for these systems include target tracking and image stabilization. In this talk we focus on the architecture of the 3D image sensor, which includes pixel-parallel analog-to-digital conversion and programmable digital processors for pixel and block operations. We show that 3D technology will allow at least an order of magnitude decrease in power dissipation over...

Signal reconstruction in oversampled A/D conversion (ADC) is classically performed by lowpass filtering the quantized signal. This leads to a mean squared error (MSE) inversely proportional to R 2n+1 where R is the oversampling rate and n is the order of the converter. However, while the estimate given by this reconstruction has the same bandwidth as that of the original analog signal, we show that it does not necessarily lead to the same digital sequence when fed into the same A/D converter. Moreover, under some assumptions, we show analytically that an estimate having the same bandwidth and giving the same digital sequence as those of the original signal should yield an MSE with an upper bound inversely proportional to R 2n+2 , instead of R 2n+1 ; that is an improvement of 3 dB per octave of oversampling, regardless of the order of the converter. We propose a structural analysis covering most currently known configurations of oversampled ADC, which enables us to identify sets o...

The high-order \Sigma-\Delta modulator is an appropriate approach for high-bandwidth, high-resolution A/D conversion. However, non-ideal effects such as the finite opamp gain and the capacitor mismatch have great impacts on its performance at a low oversampling ratio. To achieve greater performance under the inevitable non-ideal effects, we explore several multiple-bit schemes, based on our CIQE high-order \Sigma-\Delta architecture, to remove the non-ideal deterioration. Design rules of these multiple-bit schemes are developed and verified by extensive simulations. I. Introduction The A/D converter is an important element for digitalsignal processing systems. The cruxes of an A/D converter are high resolution for precise representation of the original signal and high bandwidth for fast processing. Conventional A/D architectures, e.g., flash, 2-step flash, and successive approximation, are not suitable for highresolution applications because of the need of near-ideal analog component...

Academic Dissertation to be presented with the assent of

Sample rate conversion (SRC) with rational factors can be realized by interpolation followed by decimation, where CIC-Filters [1] can be chosen for either. However, the necessary increase of the sample rate that goes with the interpolation is not feasible in most RF-applications. Therefore a time-variant implementation of CIC-filters is presented which circumvents the high intermediate sample rate. This time-variant implementation results in a linear periodically time-variant system (LPTV) which is completely equivalent to its original linear time-invariant system (LTI) consisting of the interpolator and the decimator. Thus well-known methods of system analysis can be used by analysing the LTI system, while implementing the system as an LPTV system, avoiding the high intermediate sample rates of the LTI system. The advantage of CIC-filters not having stored the coefficients of the impulse response but rather the description of the impulse response, enabling an implementation which is independent of the interpolation- as well as the decimation-factor, is preserved with the LPTV system. In contrast to Lagrange interpolators cancelling only the image components of the interpolated signal, time-variant CIC-filters also cancel the aliasing components, which is important in applications, where antialiasing is more important than anti-imaging.

c○2004 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.