The logic representation of analog circuits based on condition parameters

This paper describes CODAC, a CAD tool for characterization and analysis of analog and digital circuits. It is based primarily on the industry standard electrical simulator, SPICE. CODAC provides a powerful C like language for specifying the characterization problem. In addition to providing an extensive library of built-in analysis functions it also supports a procedural interface that facilitates the definition of customized analysis functions. A capability to distribute in parallel the large number of simulation runs for an extensive circuit analysis (e.g. Monte Carlo analysis) is provided which significantly reduces overall cycle time. CODAC is being successfully used for circuit analysis and as a part of analog and digital library development flow at Texas Instruments.

7 - Analog Interfacing

Thin and thick film materials are widely used in modern electronic circuits due to their ability to provide miniaturization, high performance, and cost-effective production. Thin film technology involves depositing layers of conductive, resistive, and dielectric materials onto a substrate, typically using methods like vacuum deposition or sputtering. Thick film technology, on the other hand, uses a screen-printing process to deposit paste-like materials onto substrates and is known for its durability and adaptability to harsh environments. Both technologies play crucial roles in designing analog and digital circuits, especially in fields like telecommunications, automotive electronics, and medical devices. The increasing demand for smaller, faster, and more efficient electronic devices has put pressure on the development of high-performance circuits using thin and thick film technologies. A key challenge is optimizing material properties to balance electrical performance, thermal management, and mechanical reliability in both analog and digital circuits. This study explores the design and performance evaluation of analog and digital circuits using thin and thick film materials. Thin film circuits were fabricated using sputtering techniques to deposit layers of resistive and conductive materials with precise thickness control. Thick film circuits were created by screen-printing conductive, resistive, and dielectric pastes onto ceramic substrates. Electrical performance was tested for both types of circuits, focusing on parameters such as resistance, capacitance, and inductance. The thin film circuits demonstrated superior electrical performance with lower parasitic inductance and capacitance, achieving a resistance tolerance of ±1% and a thermal coefficient of resistance (TCR) of ±50 ppm/°C. The thick film circuits, while having slightly higher parasitic values, offered robustness and mechanical stability in high-temperature environments, with TCR values ranging from ±100 to ±250 ppm/°C. Both technologies showed significant promise, with the choice of material depending on the specific application requirements for analog and digital systems.

Recent advances in programmable analog circuits have made it possible to consider analog signal processing as an alternative to some digital signal processing. We discuss the use of analog floating-gate devices for signal processing applications. We also discuss the motivation for doing more signal processing in analog circuits before the analog-to-digital conversion. Finally, we present an overview of the trade-offs in implementing functions in analog VLSI vs. digital VLSI; including power consumption, linearity, SNR, and dynamic range in analog and digital circuits for signal processing hardware.

This paper presents a novel digital instrument designed for measuring radiation doses in Ethanol-Chlorobenzene (ECB) dosimeters, based on oscillometry method. ECB dosimeters are versatile tools for radiation measurement, particularly in medical and industrial applications. Various components of the device including measuring cell, analog and digital circuits were designed, simulated, optimized and verified. The measuring cell was manufactured to maximize the sensitivity in detecting changes in the conductivity of the ECB solution inside the ampoules. The analog oscillating circuit was fabricated using new and common elements in the market such as operational amplifiers (Op Amps), diodes and transistors. The oscillator frequency was set to the lowest possible value to reduce the adverse effects of high frequencies. However, further decrease in frequency causes the conductivity changes of the ECB solution to be measured by the analog circuit inefficiently. The digital circuit was designed and constructed to interface with the analog circuit, processing its output voltage. This digital circuit included an ATmega8A microcontroller, a DS18B20 temperature sensor, a graphic LCD, and other widely used integrated circuits (ICs). The overall performance of the apparatus was validated by reading the absorbed dose of a set of dosimeters irradiated at doses of 1, 5, 10, 30, 70, and 100 kGy in the Gamma cell GC-220 of our laboratory. The maximum absolute relative difference between the average dosimeter readouts and expected values was about 7% and the average value of the absolute relative differences at different doses was about 3.3%. The negligible discrepancy between the values read by the manufactured device and the actual values demonstrates the accuracy of the device operation. Therefore, this device can be considered as an appropriate apparatus for reading the ECB dosimeters and can serve as a key component of an ECB dosimetry system for high-dose dosimetry applications.

In order to compensate for the effects of supply voltage, process and temperature on the oscillator frequency, we design a ring oscillator with digital calibration. By comparing the frequency deviation between the ring oscillator and the external reference clock source, adjusting the state of the control word, and then changing the number of resistors in the analog circuit to adjust the output frequency of the ring oscillator, so as to compensate the output frequency deviation. Firstly, we analyze the analog circuit and digital circuit, and then get the result of simulation, finally carry out the layout design. Simulation results show that by digital calibration, the output frequency can be adjusted up or down by 30%, so that the deviation can be compensated to a great extent.

There are several attempts to use chaotic nonlinear maps for random number generation. Theoretically, some chaotic maps can produce balanced and i.i.d. (independent and identically distributed) binary sequences. Also, chaotic binary sequences with prescribed auto-correlations can be generated. However, it is difficult to generate aperiodic sequences with prescribed auto-correlation properties by analog circuits or digital circuits only. In this paper, we propose a simple post-processing by linear feedback shift registers for generating random bit sequences with prescribed (positive/negative) auto-correlations. We perform some numerical experiments for investigating the effects of the proposed post-processing.

International Journal of Microelectronics and Digital Integrated Circuits is a peer-reviewed journal that publishes original research concerning microelectronics and digital integrated circuits, while also including analog circuits, digital circuits, embedded systems and MOSFET transistors.

GaAs buffer layers grown by molecular-beam epitaxy (MBE) at low temperatures (200-300 degrees C) have been successfully used to reduce sidegating in both MESFETs and MODFETs. There are, however, high concentrations of defects in the low-temperature (LT) buffers that adversely affect the high-frequency performance of precision analog and certain digital circuits. In unoptimized structures, nanosecond and microsecond transients are as large as 85 and 15% of the total voltage swing, respectively. These transients cause various detrimental effects in circuits. These effects are described. Their origin is attributed to the outdiffusion of defects from the LT buffer, and a method for optimizing the device structure for minimum sidegating and maximum high-frequency performance is presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

In this work, we report on the significance of non-overlap channel architecture in nanoscale double gate (DG) FETs to improve performance of low-voltage analog and digital circuits. It is shown that the low-voltage operation of a cascoded Operational Transconductance Amplifier (OTA) and 6-T SRAM cell can be considerably enhanced using underlap gate-source/drain design. The present work provides new opportunities for realizing future low-voltage analog and digital circuits with underlap DG FETs.

Mixed-signal 3D-ICs have a stacked structure of digital and analog circuit chips. In this study, the effect of noise propagation from a digital circuit on an analog circuit was evaluated using an actual mixed-signal 3D-IC. The noise propagation via through-silicon vias (TSVs) was measured, with a ring-oscillator as a noise source. For a comprehensive investigation, TSV-liner interface states were evaluated along the depth direction using unique multiwell-structured TSVs and a charge-pumping method. It was considered that the interface traps and nonconformal thickness of the TSV liner increased the noise propagation among stacked chips.

Spacecraft electronics are affected by the space radiation environment. Among the different types of radiation effects that can affect spacecraft electronics is the single event transients. The space environment is responsible for many of the single event transients which can upset the performance of the spacecraft avionics hardware. In this paper we first explore the origins of single event transients, then explore the modeling of a single event transient in digital and analog circuit. The paper also addresses the concept of crosstalk that could develop among digital circuits in the present of a SET event. The paper ends with a brief discussion of SET hardening. The goal of the paper is to provide methodologies for assessing single event transients and their effects so that spacecraft avionics engineers can develop either hardware or software countermeasures in their designs.

Spacecraft electronics are affected by the space radiation environment. Among the different types of radiation effects that can affect spacecraft electronics is the single‐event transient (SET). This chapter explores the origins of SETs and their effects as outlined by many scientists and researchers, many of which are mentioned in the references. It also explores the modeling of a SET in digital and analog circuit. The chapter also addresses the concept of crosstalk that could develop among digital circuits in the present of a SET event. It provides a discussion of SET hardening. The chapter presents a qualitatively methodology for assessing SETs and its effects so that spacecraft avionics engineers can develop either hardware or software countermeasures in their designs. Single‐event effects is the general term used when space energetic particles are capable of creating an electrical response in an electronics device.

In traditional yield enhancement approaches, a lot of computation efforts have to be paid first to find the feasible regions and the Pareto fronts, which will become a heavy cost for large analog circuits. In order to reduce the computation efforts, this work tries to finish all iteration steps of the yield enhancement flow at behavior level. First, a novel force-directed nominal point moving (NPM) algorithm is proposed to find a better nominal point without building the feasible regions. Then, an equation-based behavior-level sizing approach is proposed to map the NPM results at performance level to behavior-level parameters. A fast behavior-level Monte Carlo simulation is also proposed to shorten the iterative yield enhancement flow. Finally, using the obtained behavioral parameters as the sizing targets of each sub-block, the device sizing time is significantly reduced instead of sizing from the system-level specifications directly. As demonstrated on a complex CPPLL design, this behavior-level approach could be another efficient methodology to help designers improve their analog circuits toward better yield.

Due to fundamental physical limitations, conventional digital circuits have not been able to scale at the pace expected from Moore’s law. In addition, computationally intensive applications such as neural networks and computer vision demand large amounts of energy from digital circuits. As a result, energy efficient alternatives are needed in order to provide continued performance scaling. Analog circuits have many well known benefits: the ability to store more information onto a single wire and efficiently perform mathematical operations such as addition, subtraction, and differential equation solving. However, analog computing also comes with drawbacks such as its sensitivity to process variation and noise, limited scalability, programming difficulty, and poor compatibility with digital circuits and design tools. We propose to leverage the strengths of analog circuits and avoid its weaknesses by using digital circuits and time-encoded computation. Time-encoded circuits also operate on continuous data but are implemented using digital circuits. We propose a novel scalable general purpose analog processor using time-encoded circuits that is well suited for emerging applications that require high numeric precision. The processor’s datapath, including time-domain register file and function units are described. We evaluate our proposed approach using an implementation that is simulated with a 0.18µm TSMC process and demonstrate that this approach improves the performance of a scientific benchmark by 4x compared against conventional analog implementations and improves energy consumption by 146x compared against digital implementations.