电流型运算放大器在应用电路中的特性研究

文中简要介绍了电流型运放的特性,着重对电流型运放的应用电路进行测试,研究电流型运放的应用特性。实验中,选择典型电流型运放及电压型运放构建负阻变换器、电压跟随器和同相比例放大器,通过对此3类应用电路的测试,分析、总结运放参数对特殊应用电路的影响,为电路设计者在具体电路的设计中恰当选择适合的放大器提供参考。     

Low-voltage subthreshold CMOS current mode circuits: Design and applications

The world has migrated to portable applications ranging from smart phones to Lab on a Chip applications. However they come with a new set of challenges for analog IC designers. Low voltage operation, small area and low noise are the critical design criteria for portable devices. This paper presents a g_m/I_D based design methodology for low voltage current mode circuits using standard CMOS technology. A second generation current conveyor (CCII) and a current feedback operational amplifier (CFA) are designed using the discussed design procedure. Both circuits operate from a single 0.4 V supply. The CCII is used to implement an instrumentation amplifier. Multiple applications are implemented using the CFA. Post layout simulation using TSMC 90 nm and UMC 130 nm technology show that the presented design procedure is an attractive solution for low voltage CMOS current mode circuits.     

A high voltage MOS switch

A novel MOS high voltage switch suitable for use in integrated circuits is described. The device doubles the operational voltage capability, compared to the standard MOS transistor used in integrated circuits. It uses a unique variable positive feedback which increases dramatically its saturation current and permits significant saving of the circuit area. The switch is fabricated using common Sigate technology. No additional processing steps are required.     

A current-/voltage-controlled four-slope operation square-/triangular-wave generator and a dual-mode pulse width modulation signal generator employing current-feedback operational amplifiers

This paper presents a current-feedback operational amplifier (CFOA)-based current-/voltage-controlled four-slope operation square-/triangular-wave generator. The proposed circuit can adjust the duty cycle of the output waveforms in a current- or voltage-controlled manner, and an external resistor is used to independently control its oscillation frequency. In addition, the DC level of the triangular wave can be adjusted by tuning an input voltage source. This paper also presents a CFOA-based dual-mode pulse width modulation (PWM) signal generator derived from the proposed square-/triangular-wave generator. The literature review in this paper includes previous designs, circuit operations, and the non-ideal effects and design considerations of the proposed circuits. Prototype circuits built with commercially available CFOA integrated circuits (ICs) (AD844ANs) and discrete passive components were used to execute experimental tests to verify the feasibility of the proposed circuits. The experimental results of this study are in agreement with the theoretical analysis.     

CMOS realization of single-resistance-controlled and variable frequency dual-mode sinusoidal oscillators employing a single DVCCTA with all-grounded passive components

In this paper, two new designs are proposed for sinusoidal oscillators based on a single differential voltage current conveyor transconductance amplifier (DVCCTA). Each of the proposed circuits comprises a DVCCTA combined with passive components that simultaneously provides both voltage and current outputs. The first circuit is a DVCCTA-based single-resistance-controlled oscillator (SRCO) that provides independent control of the oscillation condition and oscillation frequency by using distinct circuit parameters. The second circuit is a DVCCTA-based variable frequency oscillator (VFO) that can provide independent control of the oscillation frequency by adjusting the bias current of the DVCCTA. In this paper, the DVCCTA and relevant formulations of the proposed oscillator circuits are first introduced, followed by the non-ideal effects, sensitivity analyses, frequency stability discussions, and design considerations. After using the 0.35-μm CMOS technology of the Taiwan Semiconductor Manufacturing Company (TSMC), the HSPICE simulation results confirmed the feasibility of the proposed oscillator circuits.     

Research Note Two novel voltage( current) controlled integrable oscillators

Two novel voltage( current) controlled oscillator circuits are presented. Each circuit uses a single operational amplifier, a single operational transconductance amplifier, and either a single resistor or a single capacitor. In both circuits the frequency of oscillation can be adjusted by changing the biasing voltage( current) of the operational transconductance amplifier. Experimental results are included     

Applications of the current feedback operational amplifiers

The current feedback operational amplifiers (CFOAs) are receiving increasing attention as basic building blocks in analog circuit design. This paper gives an overview of the applications of the CFOAs, in particular several new circuits employing the CFOA as the active element are given. These circuits include differential voltage amplifiers, differential integrators, nonideal and ideal inductors, frequency dependent negative resistors and filters. The advantages of using the CFOAs in realizing low sensitivity universal filters with grounded elements will be demonstrated by several new circuits suitable for VLSI implementation. PSPICE simulations using the AD844-CFOA which indicate the frequency limitations of some of the proposed circuits are included.     

Driving schemes for a-Si and LTPS AMOLED displays

Design of stable active matrix organic light-emitting diode (AMOLED) displays comes with significant challenges that stem from the electrical property of the backplane materials, line parasitics in the matrix, and the opto-electronic property of the organic light-emitting diode (OLED). This paper reviews voltage and current programming schemes for AMOLEDs. Following a systematic review of pixel circuits, design considerations are examined for both current and voltage schemes with focus on stability and programming speed for both amorphous silicon (a-Si) and low temperature polysilicon (LTPS) pixel circuits. In particular, spatial parameter variations and stability, which hinder reliable operation of AMOLED display backplanes, are discussed. Analysis shows that while driving schemes reported hitherto maybe suitable for small and medium size displays, new schemes are critically needed for large-area high-resolution AMOLED displays.     

Design and implementation of monostable multivibrators employing differential voltage current conveyors

In this paper, two novel application circuits utilizing the differential voltage current conveyor (DVCC) are introduced and implemented. To the best knowledge of authors, this is the first reported monostable multivibrators employing DVCC device. Each presented circuit is constructed by single DVCC as the basic active building block together with a few passive components. Both of them can be operated via a positive-edge triggering signal to generate a pulse waveform with an adjustable width. The first one is a general monostable circuit. The second design is an improved construction, which shortens the recovery time for applying the consecutive triggering signals. The circuit operations are first described and then the non-ideal issues and design considerations of the proposed circuits are discussed. To demonstrate their feasibility, the presented circuits are simulated using circuit simulation program Is-Spice. Available commercial ICs and discrete components are used to implement the prototype circuits. Simulation and experimental results agree well with the theoretical analysis.     

A New PWM-Controlled Quasi-Resonant Converter for a High Efficiency PDP Sustaining Power Module

A new pulsewidth modulation (PWM)-controlled quasi-resonant converter for a high-efficiency plasma display panel (PDP) sustaining power module is proposed in this paper. The load regulation of the proposed converter can be achieved by controlling the ripple of the resonant voltage across the primary resonant capacitor with a bidirectional auxiliary circuit, while the main switches are operating at a fixed duty ratio and fixed switching frequency. Hence, the waveforms of the currents can be expected to be optimized from the view-point of conduction loss. Furthermore, the proposed converter has good zero-voltage switching (ZVS) capability, simple control circuits, no hign-voltage ringing problem of rectifier diodes, no dc offset of the magnetizing current and low-voltage stresses of power switches. Thus, the proposed converter shows higher efficiency than that of a half-bridge LLC resonant converter under light load condition. Although it shows the lower efficiency at heavy load, because of the increased power loss in auxiliary circuit, it still shows the high efficiency around 94%. In this paper, operational principles, features of the proposed converter, and analysis and design considerations are presented. Experimental results demonstrate that the output voltage can be controlled well by the auxiliary circuit using the PWM method.      

Amorphous silicon thin film transistor circuit integration for organic LED displays on glass and plastic

This paper presents design considerations along with measurement results pertinent to hydrogenated amorphous silicon (a-Si:H) thin film transistor (TFT) drive circuits for active matrix organic light emitting diode (AMOLED) displays. We describe both pixel architectures and TFT circuit topologies that are amenable for vertically integrated, high aperture ratio pixels. Here, the OLED layer is integrated directly above the TFT circuit layer, to provide an active pixel area that is at least 90% of the total pixel area with an aperture ratio that remains virtually independent of scaling. Both voltage-programmed and current-programmed drive circuits are considered. The latter provides compensation for shifts in device characteristics due to metastable shifts in the threshold voltage of the TFT. Various drive circuits on glass and plastic were fabricated and tested. Integration of on-panel gate drivers is also discussed where we present the architecture of an a-Si:H based gate de-multiplexer that is threshold voltage shift invariant. In addition, a programmable current mirror with good linearity and stability is presented. Programmable current sources are an essential requirement in the design of source driver output stages.     

A novel COA-based electronically adjustable current-mode instrumentation amplifier topology

In this paper a new topology for implementing Current-Mode Instrumentation Amplifiers (CMIA) is presented. The proposed CMIA is based on two single input-multiple output (SI-MO) current operational amplifiers (COAs) as basic building blocks and 2 resistors. To electronically control the differential-mode gain, a transistor operating in triode region is used which acts as a variable resistor. The significant feature of the proposed CMIA is that the active building blocks operate in closed loop configuration. Therefore it exhibits numerous remarkable features such as improved frequency performance, low THD and very low input impedance. In addition, it has fully differential output which reduces the output noise and increases its application. The proposed CMIA is analyzed and simulated with SPICE program using parameters of 0.18 µm CMOS technology and supply voltage of ±0.9 V.     

A wide-band, low-power, high slew rate voltage-feedback operationalamplifier

A wide-band low-power voltage-feedback operational amplifier on a 3 GHz, 40 V complementary bipolar technology is described. The class AB input stage takes advantage of some current-boost transistors which enhance and linearize the slew-rate during large-signal operation without increasing the power consumption. The triple-buffered output stage provides 100 mA of load current maintaining good linearity. Since the circuit design and technology development were concurrent, several different circuits were stepped into one wafer to fully characterize the process and identify the best product candidates. The low-current version of this chip has a quiescent current of 2.5 mA, 2000 V/μs slew rate and gain bandwidth of 110 MHz. The medium-current version draws only 6.5 mA of current at the same supply voltage while the slew rate increases to 3500 V/μs and bandwidth to 210 MHz. Both parts are operational from +/-2.75 V to +/-18 V supply range. Die size is 51 mils by 76 mils on a poly-emitter CB process     

Low voltage analog circuit design techniques

Analog signal processing is fast and can address real world problems. The applications of battery powered analog and mixed mode electronic devices require designing analog circuits to operate at low voltage levels. In this paper, some of the issues facing analog designers in implementing low voltage circuits are discussed, and possible low voltage design techniques are examined. The authors describe briefly almost all low voltage design techniques suitable for analog circuit structures along with their merits and demerits     

Fault detection in CMOS/SOI mixed-signal circuits using the quiescent current test

Main stream bulk CMOS and the variants of silicon-on-insulator (SOI) CMOS technologies are discussed with respect to testing for the quiescent current of mixed-signal integrated SOI circuits. The 2–3 times lower static power consumption in fully depleted CMOS/SOI compared to bulk CMOS allows quiescent current testing also for high performance analogue circuits at an acceptable defect resolutions. From first simulations and technological considerations, it turned out that quiescent current tests are able to detect not only commonly known defects, but also SOI specific defects such as self-heating, kink-effect or the parasitic bipolar behaviour. It is further shown that in partially depleted thick-film SOI, the kink-effect and parasitic bipolar transistor support the quiescent current test for some specific defects as they elevate the defective quiescent current level. In fully depleted kink-free SOI circuits, the kink-effect may occur due to process failures but then can be detected by quiescent current tests. A special fault simulation model for the kink-effect is presented. The I_ccq test technique is studied for a CMOS/SOI Miller operational amplifier. Normal 6-σ variation of the aspect ratio and the threshold voltage do not jeopardise the defect detection in the quiescent current. First, results confirm the good detection capabilities of the quiescent current test, in particular, of failures which are not visible in the output voltage.     

Impact of Supply Voltage Variations on Full Adder Delay: Analysis and Comparison

In this paper, some of the most practically interesting full adder topologies are analyzed in terms of their delay dependence on the supply voltage fluctuations, which are a major contribution to the delay uncertainty, which in turn limits the speed performance of current VLSI circuits. Analytical models of the delay sensitivity with respect to supply variations are derived by following a simplified circuit analysis, and the resulting expressions are simple enough to afford a deeper insight into the impact of supply voltage variations on each topology. The models are shown to be sufficiently accurate through simulations with CMOS technologies having a minimum feature size ranging from 90 nm to 0.35 mum. Several interesting properties and design considerations are derived from these models, and the effect of the supply voltage scaling, technology scaling, transistor sizing, and input transition time is discussed. Strategies to evaluate the delay sensitivity since the early design phases (e.g., from ring oscillator measurements) are also introduced. As a fundamental result, it is shown that the delay sensitivity to supply variations will increase in the next technology nodes, thus, it is expected that controlling the supply variations will be an increasingly important issue in the design of the next generation VLSI circuits. The proposed methodology is also analyzed in the case of more general digital circuits, and is used to estimate the impact of the inter-die threshold voltage variations on the delay of the considered full adder topologies     

用线性变换运算电流放大器(TOCA)的电流处理电路

本文描述最近引入的新的多功能有源器件—线性变换运算电流放大器的基本性质以及它在电流处理电路中的应用.     

集成运算放大器构成交流放大电路的分析和设计

用集成运算放大器构成的交流放大电路具有线路简单、免调试、故障率低等优点。文章全面介绍集成运算放大器构成的各种交流放大电路,详细分析和充分论述电路的组成、工作原理、以及电压增益、输入电阻等参数的计算;说明运放交流放大电路的设计,这有助于合理设计和使用集成运算放大器构成的交流放大电路。     

Low-voltage and low-power circuit design for mixed analog/digitalsystems in portable equipment

This paper describes low-voltage and low-power (LV/LP) circuit design for both analog LSI's and digital LSI's which are used in mixed analog/digital systems in portable equipment. We review some LV/LP circuits used in digital LSI's, such as general logic gate, DSP, and DRAM, and others used in analog LSI's, such as operational amplifiers, video-signal processing circuits, A/D and D/A converters, filters, and RF circuits, along with a wide range of items used in recently developed LSI's. Since analog circuits have fundamental difficulties in reducing the operating voltage and the power consumption, in spite of recent progress in LV/LP circuit techniques, these difficulties will be a major issue for decreasing the total power consumption of some mixed analog/digital systems used in portable equipment     

The use of current amplifiers for high performance voltage applications

A current amplifier is used to realize a voltage amplifier having an improved high frequency response and slew rate capability. It is shown that the closed loop bandwidth is independent of the closed loop voltage gain. The design and application of a unity gain and a high gain current amplifier to voltage signal processing circuits are given. The results demonstrate an efficient use of the inherent frequency response capabilities of the active devices in the circuit to achieve the amplification of high frequency and large amplitude voltage signals.