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Analog to Digital Conversion

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Analog to Digital Conversion (ADC) is the process of transforming continuous analog signals into discrete digital values. This conversion enables the representation, processing, and storage of analog information in digital form, facilitating the use of digital systems for analysis, communication, and computation.
lightbulbAbout this topic
Analog to Digital Conversion (ADC) is the process of transforming continuous analog signals into discrete digital values. This conversion enables the representation, processing, and storage of analog information in digital form, facilitating the use of digital systems for analysis, communication, and computation.

Key research themes

1. How can innovative circuit architectures improve the efficiency and performance of analog-to-digital converters under hardware and power constraints?

This theme investigates novel ADC circuit designs and architectures that address limitations in speed, power consumption, integration complexity, and noise performance. It focuses on leveraging advanced hardware implementations such as time-encoding, switched-capacitor systems, and FPGA-based architectures to reduce power demands and complexity while maintaining or improving ADC accuracy and robustness, especially in high-frequency and hybrid systems.

Key finding: Introduces VCO-based time-encoding ADCs that encode analog signals as modulated square waves, enabling first-order noise shaping which improves signal-to-quantization-noise ratio (SQNR) with oversampling. The architecture... Read more
Key finding: Demonstrates the use of field-programmable analog arrays (FPAAs) to rapidly prototype mixed-signal algorithmic ADCs, such as serial algorithmic converters, achieving flexible, low-cost, and scalable development. The method... Read more
Key finding: Presents an FPGA-based sigma-delta ADC using low-voltage differential signaling (LVDS) I/O pads as built-in 1-bit comparators, requiring minimal external analog circuits (just an RC integrator). This implementation leverages... Read more
Key finding: Develops a technique for directly interfacing analog voltage-output sensors to digital input ports of microcontrollers or FPGAs without ADCs. The method involves measuring the duty cycle of a digital square-wave signal... Read more
Key finding: Proposes a Compressed Sensing (CS) ADC architecture that leverages the capacitive array of charge-redistribution SAR ADCs for passive, low-power sub-Nyquist sampling and linear combination of input signals. The design omits... Read more

2. How can sampling and quantization processes be jointly optimized for task-specific digital acquisition systems using learnable or adaptive frameworks?

This research area focuses on adaptive, data-driven ADC design where sampling and quantization are co-optimized in holistic systems tailored for specific tasks such as communication symbol detection or medical imaging. It addresses deficiencies of traditional uniform ADC schemes by leveraging machine learning to learn non-uniform mappings and optimize bit allocation, sampling rates, and processing pipelines end-to-end, improving overall task performance under constrained resource budgets.

Key finding: Proposes a task-oriented end-to-end learnable ADC framework that jointly optimizes nonlinear sampling and quantization mappings with analog combining and digital processing for task-specific objectives. By utilizing... Read more

3. What are effective digital and signal processing strategies to mitigate noise, mismatches, and intersymbol interference in ADC systems, especially in high-speed or constrained-resolution scenarios?

This theme covers algorithmic and signal processing methods for error correction and calibration in ADCs, focusing on mismatch compensation in time-interleaved ADC arrays, noise shaping in sigma-delta modulators, and iterative algorithms for ISI mitigation in monobit digitized ultra-wideband systems. These methods enable improved effective resolution and system-level performance despite hardware non-idealities and limitations in resolution or sampling precision.

Key finding: Introduces a two-stage iterative detection algorithm specialized for monobit digitized ultra-wideband signals affected by noise and severe intersymbol interference (ISI). The algorithm cancels forward and backward ISI by... Read more
Key finding: Presents a novel pilot-based online adaptive estimator for timing mismatch errors in time-interleaved ADCs (TI-ADCs) used in impulse radio ultra-wideband receivers. The method derives closed-form expressions for Gaussian and... Read more
Key finding: Proposes a low-pass filtering switched-capacitor DAC (LPSC-DAC) within one-bit continuous-time sigma-delta modulators (CTSDMs) which filters the DAC feedback signal in the discrete-time domain. This filtering effectively... Read more

4. How can digital filter transformations and hybrid signal processing improve digital signal conditioning and reduce artifacts in ADC outputs?

This theme investigates digital domain frequency transformations for filter design, hybrid analog-digital processing to achieve desired spectral characteristics, and methods to improve ADC output quality by addressing noise, distortion, and aliasing through filter design and implementation. It is especially relevant to high-resolution filtering stages following analog-to-digital conversion for signal enhancement and reconstruction accuracy.

Key finding: Develops a novel algorithm for transforming a digital low-pass filter into low-pass, high-pass, band-pass, band-stop, and narrow-band digital filters within the digital domain using bilinear and inverse bilinear z-transforms... Read more
Key finding: Provides detailed theoretical foundations for digital filter design including FIR and IIR structures, frequency response characterization, and convolution operations. Emphasizes the digital signal filtering as a principal DSP... Read more

All papers in Analog to Digital Conversion

Objective-Modern multielectrode array (MEA) systems can record the neuronal activity from thousands of electrodes, but their ability to provide spatio-temporal patterns of electrical stimulation is very limited. Furthermore, the... more
A/D converters for single chip CMOS imagers have often been designed using the column-parallel approach, employing a slow A/D converter for each column of the sensor array. This thesis investigates a serial approach utilizing a single... more
Structural health monitoring (SHM) is a method of localizing damage in infrastructures regarding structural strain, vibration or movements due to external contributing factors which mainly occur as a result of natural disasters. The need... more
This paper presents the design and experimental results of a continuous-time (CT) sigma-delta (ΣΔ) modulator with data-weighted average (DWA) technology for WiMAX applications. The proposed modulator comprises a third-order active RC loop... more
Imbalance and out-of-range input signals can cause inaccuracy in fully differential successive approximation (SAR) analog to digital converter (ADC). Therefore, implementation of an ADC driver can solve the problem since the input can be... more
A communication system based on transmit-reference (TR) ultra-wideband (UWB) is studied and further developed. Introduced by Hoctor and Tomlinson, the aim of the TR-UWB transceiver is to provide a straightforward impulse radio system,... more
Practical simulation and measurement methods based on impulse sensitivity functions to characterize the sampling aperture of clocked comparators are demonstrated on a 90 nm CMOS testchip. The results comparing a StrongARM latch and a CML... more
An asynchronous 6 bit 1 GS/s ADC is achieved by time interleaving two ADCs based on the binary successive approximation (SA) algorithm using a series capacitive ladder. The semi-closed loop asynchronous technique eliminates the high... more
Lectures for the Computer Architecture are conceived to get the students acquaint with the architecture and basic properties of the computers in general with emphasis to the basic building components and their properties. We created a set... more
Objective: To supply quantitative information about the facial soft tissues of adult operated patients with cleft lip and palate (CLP). Design, Setting, and Patients: The three-dimensional coordinates of soft tissue facial landmarks were... more