Radio frequency electronics on plastic

In this paper the recent progress of active high frequency electronics on plastic is discussed. This technology is mechanically flexible, bendable, stretchable and does not need any rigid chips. Indium Gallium Zinc Oxide (IGZO) technology is applied. At 2 V supply and gate length of 0.5 μm, the thin-film transistors (TFTs) yield a measured transit frequency of 138 MHz. Our scalable TFT compact simulation model shows good agreement with measurements. To achieve a sufficiently high yield, TFTs with gate lengths of around 5 μm are used for the circuit design. A Cherry Hopper amplifier with 3.5 MHz bandwidth, 10 dB gain and 5 mW dc power is presented. The fully integrated receiver covering a plastic foil area of 3 × 9 mm2 includes a four stage cascode amplifier, an amplitude detector, a baseband amplifier and a filter. At a dc current of 7.2 mA and a supply of 5 V, a bandwidth of 2 - 20 MHz and a gain beyond 15 dB were measured. Finally, an outlook regarding future advancements of high frequency electronics on plastic is given

전류 센싱 피드백 시스템을 이용한 고안정성 산화물 TFT 쉬프트 레지스터의 설계 및 제작

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2017. 2. 정덕균.Integration of shift registers on the glass panel allows the display to be thinner, lighter, and cheaper to produce, thanks to the reduction of the number of ICs for scanning horizontal lines. Circuits of the shift register employing n-type thin film transistors (TFTs), such as hydrogenated amorphous silicon (a-Si:H) and oxide TFTs, have been reported. Recently, oxide TFTs attract much attention due to their high mobility (5~10 cm2/V∙s) compared with that of a-Si:H TFT (0.8cm2/V∙s). However, oxide TFTs often suffer from severe degradation of the threshold voltage (VTH) against the temperature and electrical stress. In this paper, in order to compensate the instability of oxide TFTs in the shift register, an oxide TFT with double gates, which can control VTH by varying the top gate bias (VTG) is adopted. The top gate of the double-gate TFT can be fabricated in the same process for the pixel IZO (Indium Zinc Oxide) so that an additional process only for the top gate is not required. Adequate VTG is provided timely, adaptively to the gate of the oxide TFTs to stabilize the threshold voltage. The fabrication result shows that the proposed shift register using VTG set at an adapted value become stable at 100℃ whereas the conventional one is mal-functioning. The optimum VTG varies from product to product and changes continuously over the lifetime of the display. Therefore, the feedback driving system suitable for the proposed shift register is required to search the optimum VTG. The system has two main functionsthe first is to sense the current of shift register and the second is the searching algorithm for finding the optimum VTG. When the transistors are degraded by an external stress, the current of the whole shift registers is changed. The information about the VTH degradation in the shift register can be gathered via current sensing circuit. The sensed current is integrated to generate the output and is forwarded to an ADC. The binary-converted current of shift register is processed by the proposed algorithm in the digital domain for obtaining an optimum VTG and then the result is converted back to analog to generate VTG. The IC implementing such functions is fabricated in a 0.18 μm BCDMOS process. When the shift register current is measured on the conventional system with increasing temperature up to 80℃, it is increased to more than 10 times than that at the room temperature. However, the proposed feedback system keeps a highly stable (<13%) current level of shift register up to 80℃ with an optimized VTG.Abstracts i Table of Contents iii List of Tables v List of Figures vi Chapter 1 Introduction 1 1.1 Background 2 1.2 Outline 7 Chapter 2 Review of oxide-based TFT device and N-type TFT circuit design 8 2.1 Overview 9 2.1.1 Characteristics of Oxide TFT 9 2.2 Oxide-based TFT 14 2.2.1 Electrical characteristics of oxide-based TFT 14 2.2.2 Stability of oxide-based TFT 18 2.3 NMOS driving circuit 24 2.3.1 Bootstrapping driving circuit 24 2.3.2 Shift register with n-type TFT 28 Chapter 3 Proposed Oxide TFT Shift Register 37 3.1 Overview 38 3.2 Characteristic of Double Gate TFT 39 3.3 Design of New shift register 46 3.3.1 Simulation Result of Conventional shift register 46 3.3.2 New shift register using Double Gate TFT 51 3.3.3 Simulation Modeling of Double Gate TFT 58 3.3.4 Simulation and Experimental Result 61 Chapter 4 Real Time Current-Sensing Feedback Compensation System 71 4.1 Overview 72 4.2 System Architecture 74 4.3 Circuit Design 77 4.3.1 Current Sensing Block 77 4.3.2 ADC/DAC Block 85 4.4 Optimum Point Searching Algorithm 100 4.5 System Verification 106 Chapter 5 Summary 116 Appendix A SPICE models 118 Bibliography 120Docto

Readout electronics for microbolometer infrared focal plane array

Ph.DDOCTOR OF PHILOSOPH

A Piecewise Linear Approximation D/A Converter for Small Format LCD Applications

Low power operation is a driving requirement for the advancement of portable consumer electronics. As products get smaller and have more functionality the device integration requirements get tighter. This is certainly true of small format LCD applications like PDAs and cell phones. Recent advances in LCD technology have allowed for advanced circuitry to be built on the glass. This allows for the unique opportunity to integrate the LCD column driver with other circuitry rather than the traditional flip chip mounting on the glass. The integration of these D/A converters with digital circuitry presents a new set of design considerations. These considerations allow for the exploration of non-traditional architectures and algorithms. This work will explore these design considerations in detail and present a novel algorithm for conversion as well as a system implementation of this algorithm. The system implementation is compared to a standard linear converter to weigh the relative advantages of each. A high performance dynamically biased amplifier is developed for use in the D/A converter. This amplifier has a high slew rate while consuming a small amount of quiescent power

From neural-based object recognition toward microelectronic eyes

Engineering neural network systems are best known for their abilities to adapt to the changing characteristics of the surrounding environment by adjusting system parameter values during the learning process. Rapid advances in analog current-mode design techniques have made possible the implementation of major neural network functions in custom VLSI chips. An electrically programmable analog synapse cell with large dynamic range can be realized in a compact silicon area. New designs of the synapse cells, neurons, and analog processor are presented. A synapse cell based on Gilbert multiplier structure can perform the linear multiplication for back-propagation networks. A double differential-pair synapse cell can perform the Gaussian function for radial-basis network. The synapse cells can be biased in the strong inversion region for high-speed operation or biased in the subthreshold region for low-power operation. The voltage gain of the sigmoid-function neurons is externally adjustable which greatly facilitates the search of optimal solutions in certain networks. Various building blocks can be intelligently connected to form useful industrial applications. Efficient data communication is a key system-level design issue for large-scale networks. We also present analog neural processors based on perceptron architecture and Hopfield network for communication applications. Biologically inspired neural networks have played an important role towards the creation of powerful intelligent machines. Accuracy, limitations, and prospects of analog current-mode design of the biologically inspired vision processing chips and cellular neural network chips are key design issues

A Second-Order ΣΔ ADC using sputtered IGZO TFTs with multilayer dielectric

This dissertation combines materials science and electronics engineering to implement, for the first time, a 2nd-order ∑∆ ADC using oxide TFTs. The transistors employ a sputtered IGZO semiconductor and an optimizeddielectric layer, based on mixtures of sputtered Ta2O5and SiO2. These dielectrics are studied in multilayer configurations, being the best results achieved for 7 layers: IG7.5 MV/cm, while keeping κ>10, yielding a major improvement over Ta2O5single-layer. After annealing at 200 °C, TFTs with these dielectrics exhibit μSAT≈13 cm2/Vs, On/Off≈107and S≈0.2 V/dec. An a-Si:H TFT RPI model is adapted to simulate these devices with good fitting to experimental data. Concerning circuits, the ∑∆ architecture is naturally selected to deal with device mismatch. After design optimization, ADC simulations achieve SNDR≈57 dB, DR≈65 dB and power dissipation, approximately, of 22 mW (VDD=10 V), which are above the current state-of-the-art for competing thinfilm technologies, such as organics or even LTPS. Mask layouts are currently under verification to enable successful circuit fabrication in the next months.This work is a major step towards the design of complex multifunctional electronic systems with oxide TFT technology, being integrated in ongoing EU-funded and FCT-funded research projects at CENIMAT and UNINOVA

Mixed-signal integrated circuits design and validation for automotive electronics applications

Automotive electronics is a fast growing market. In a field primarily dominated by mechanical or hydraulic systems, over the past few decades there has been exponential growth in the number of electronic components incorporated into automobiles. Partly thanks to the advance in high voltage smart power processes in nowadays cars is possible to integrate both power/high voltage electronics and analog/digital signal processing circuitry thus allowing to replace a lot of mechanical systems with electro-mechanical or fully electronic ones. High level modeling of complex electronic systems is gaining importance relatively to design space exploration, enabling shorter design and verification cycles, allowing reduced time-to-market. A high level model of a resistor string DAC to evaluate nonlinearities has been developed in MATLAB environment. As a test case for the model, a 10 bit resistive DAC in 0.18um is designed and the results were compared with the traditional transistor level approach. Then we face the analysis and design of a fundamental block: the bandgap voltage reference. Automotive requirements are tough, so the design of the voltage reference includes a pre-regulation part of the battery voltage that allows to enhance overall performances. Moreover an analog integrated driver for an automotive application whose architecture exploits today’s trends of analog-digital integration allowing a greater range of flexibility allowing high configurability and fast prototipization is presented. We covered also the mixed-signal verification approach. In fact, as complexity increases and mixed-signal systems become more and more pervasive, test and verification often tend to be the bottleneck in terms of time effort. A complete flow for mixed-signal verification using VHDL-AMS modeling and Python scripting is presented as an alternative to complex transistor level simulations. Finally conclusions are drawn