7 - Analog Interfacing

Data transmission via audio link on AM radio system is shown to be achievable by using Acoustic OFDM. We employ Acoustic OFDM to embed data onto audio contents that are then broadcast as AM radio signals. We tuned the parameters, and performed experiments. Text data as URL can be delivered to mobile phone through existing MF AM radio system and radios.

From AM radio to color television, broadcasting raised enormous practical and policy problems in United States, especially in relation to federal government's role in licensing and regulation. How did technological change, corporate interest, and political pressures bring about world that station owners work within today (and that tuned-in consumers make profitable)? In Radio and Television Regulation, Hugh R. Slotten examines choices that confronted federal agencies-first Department of Commerce, then Federal Radio Commission in 1927, and seven years later Federal Communications Commission-and shows impact of their decisions on developing technologies. Slotten analyzes policy debates that emerged when public implications of AM and FM radio and black-and-white and color television first became apparent. His discussion of early years of radio examines powerful personalities-including navy secretary Josephus Daniels and commerce secretary Herbert Hoover-who maneuvered for government control of the wireless. He then considers fierce competition among companies such as Westinghouse, GE, and RCA, which quickly grasped commercial promise of radio and later of television and struggled for technological edge and market advantage. Analyzing complex interplay of factors forming public policy for radio and television broadcasting, and taking into account ideological traditions that framed these controversies, Slotten sheds light on rise of regulatory state. In an epilogue he discusses his findings in terms of contemporary debates over high-resolution TV.

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.

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.

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.

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.

What Next in Computer Technology?

This paper presents the synthesis technique available in S/sup 3/E/sup 2/S, a CAD environment to specify, simulate, and synthesize electronic systems that can be modeled as a combination of analog parts, digital hardware, and software. S/sup 3/E/sup 2/S is based on a distributed, object-oriented system model, where abstract objects are initially used to express complex behavior and may be later refined into digital or analog hardware and software. Finally, system synthesis is targeted to a set of complex processors, which can be either custom designed or off-the-shelf components. The environment selects processors that best match the desired application by analyzing processor and application characteristics. The paper explains the architecture selection process with some examples.

The development of mixed signal modelling languages such as VHDL-AMS and Verilog-A allows the behaviour of analogue and mixed signal circuits to be described at a higher level than is possible with conventional circuit-level (e.g. SPICE type) simulators. Mixed-signal simulators for these new languages can process such behavioural models far more efficiently than was previously possible. The non-linear characteristics of many circuits require differential equations to be used in the behavioural descriptions. Unfortunately, the methods used to solve these equations in a mixed-signal simulator are more computationally demanding than those required to evaluate the logic expressions used to describe digital circuits. Consequently, the simulation of analogue and mixed-signal circuits is still far less efficient than the simulation of a pure digital circuit. This paper presents an alternative approach to modelling the behaviour of analogue and mixed-signal circuits based upon piecewise linear (PWL) waveforms. Since the signals processed by these models are linearised, direct methods (i.e. non-iterative) can be used to simulate their behaviour. Several alternative methods are discussed. Examples showing the application of this approach to commonly used circuits are developed and the results compared against corresponding models written for conventional simulators. Finally, suggestions are given for implementing these techniques in a VHDL simulators. (6 pages)

To verify mixed-signal SoC on the function and behavior level, one of the challenges is how to represent both analog circuits and digital circuits in a consistent model. The reason is that the performance representations of analog circuits and digital circuits are quite different. This paper addresses an innovative logic representation used for analog circuit description. This logic representation is based on the condition parameter and the concept of the efficient function. The analog circuits or system can be described in the efficient function form. Therefore, the consistent verification on functions and behavior of the mixed-signal SoC can be reached.

Widely used in telecom, television, music players, and controllers, a digital-to-analog converter (DAC) is a device that converts a digital signal into an analog signal. As integrated circuits (ICs) technologies develop, the modulation process has shifted from analog circuits to digital circuits, and the signal has been converted from a digital signal field to an analog signal field. Generally, the design of digital circuits is simpler than that of analog circuits, so the transferring can decline the requirement and difficulty of the system design. How the final DAC performs on the printed circuit board (PCB) directly affects the system's specifications. Therefore, verifying the final parameters of the DAC becomes an important task for the whole test. The DAC chip static parameters DNLity (DNL) and integral nonlinearity (INL) require measuring all points to get the calculated results. It will cost a long time if reading and recording are done by humans. This paper presents a fast and effective method to measure the static parameters of the DAC chip. The test time depends on the measurement accuracy and data. In this paper, the chip independently developed by Beijing Smart-Chip Microelectronics Technology Co. is used as a test case for testing. The results show that the DAC testing method mentioned in this paper can greatly shorten the testing time compared with manual testing.

Fault identification of analog and mixed signal circuits is very difficult topics for previous few decades. Localization of hard and soft faults in analog circuit is often a troublesome task without a transparent cut methodology. For manufacturing process of Very Large Scale Integration (VLSI) Application Specific Integrated Circuits (ASICs) both fault diagnosis and localization are mandatory. The importance of such analog test has become important due to enhancement of networking and communication sector. This paper gives a brief review on the faults present in analog circuits and different diagnosis methodologies of these faults. Comparison of detection is also demonstrated among some techniques for some of the ITC97 Benchmark circuits.

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.