差分式CMOS连续时间电流模式滤波器

提出了基地电流镜电路的差分式连续时间电流模式积分器，并用此积分器构成了全差分式连续时间电流模式低通及带通滤波器，分析并模拟了所提出的积分器及滤波器的特性，结果表明所提出了电路的具有结构简单，对称性好，失真小等优点，适于全集成。     

CCII-Based Grounded to Floating Immittance Converter and a Floating Inductance Simulator

A new circuit employing second-generation current conveyors (CCIIs), and unmatched resistors for converting a grounded immittance to the corresponding floating immittance with either positive or negative adjustable multiplier, is presented. Moreover, the proposed circuit can also realize a synthetic floating inductance employing a grounded capacitor depending on the passive element selection. Simulation results using 0.35 μ m TSMC CMOS technology parameters are given. Erkan Yuce was born in 1969 in Nigde, Turkey. He received the B.Sc. from Middle East Technical University and M.Sc. degrees from Pamukkale University in 1994 and 1998 respectively. He is a Ph.D. student at Bogazici University all in Electrical and Electronics Engineering. He is currently Research Assistant at the Electrical and Electronics Engineering Department of Bogazici University. His current research interests include analog circuits, active filters, synthetic inductors, and current-mode circuits. He is the author or co-author of about 10 papers published in scientific journals or conference proceedings. Oguzhan Cicekoglu was born in 1963 in Istanbul, Turkey. He received the B.Sc. and M.Sc. degrees from Bogazici University and the Ph.D. degree from Istanbul Technical University all in Electrical and Electronics Engineering in 1985, 1988 and 1996 respectively. He served as lecturer at the School of Advanced Vocational Studies Electronics Prog. of Bogazici University where he held various administrative positions between 1993 and 1999, and as part time lecturer at various institutions. He was with Biomedical Engineering Institute between 1999 and 2001. He is currently Associate Professor at the Electrical and Electronics Engineering Department of Bogazici University. His current research interests include analog circuits, active filters, analog signal processing applications and current-mode circuits. He is the author or co-author of about 150 papers published in scientific journals or conference proceedings. Oguzhan Cicekoglu is a member of the IEEE. Shahram Minaei received his B.Sc. degree in Electrical and Electronics Engineering from Iran University of Science and Technology in 1993. He received his M.Sc. and Ph.D. degrees in Electronics and Communication Engineering from Istanbul Technical University in 1997 and 2001, respectively. He is currently an Associate Professor at the Electronics and Communication Engineering Department of Dogus University in Istanbul, Turkey. He has more than 50 journal or conference papers in scientific review. He served as reviewer for a number of international journals and conferences. His current field of research concerns current-mode circuits and analog signal processing. Shahram Minaei is a member of the IEEE.     

Switched-current circuit design issues

Switched-current (SI) circuits represent a current-mode analog sampled-data signal processing technique realizable in standard digital CMOS technologies. Unlike switched-capacitor (SC) circuits, SI circuits require only a standard digital CMOS process. SI circuits use MOS transistors as the storage elements to provide analog memory capability. Similar to the operation of dynamic logic circuits, a voltage is sampled onto the gate of a MOSFET and held on its noncritical gate capacitance. The held voltage signal on the gate causes a corresponding held current signal in the drain, usually proportional to the square of the gate-to-source voltage. Design issues related to the implementation and performance of SI circuits are presented. SI filters show comparable performance to SC filters except in terms of passband accuracy. The major source of error is nonunity current gain in the SI integrator due to device mismatch and clock-feedthrough effects. For the initial CMOS prototypes, the current track and hold (T/H) gain error was about 2.5%     

Cascadable Current-Mode Biquads

New procedures are presented that yield cascadable, opamp based current-mode biquads from voltage-mode biquads without the use of voltage-mode to current-mode transformations. The opamps in the resulting current-mode circuits can be replaced by current-mode devices, such as current conveyors, producing circuits that are fully current-mode. The procedures are applied to several multi-opamp voltage-mode circuits to achieve current-mode lowpass, highpass, bandpass, notch, and allpass filters. The procedures are also applied to a single opamp circuit. Experimental results are given.     

The Effects of Non-Idealities and Current Limitations on the Simulated Inductances Employing Current Conveyors

Active devices such as current conveyors play an essential role on the performance of simulated inductances. The effects of second-generation current conveyor (CCII) non-idealities on the proposed and on the previously published inductances are investigated, in which lossless inductances are realized. CCIIs like all active devices have terminal current limitations that can not be exceeded. Thus, the values of the applied input current sources for the proposed and previously published inductances depending on the passive elements values and applied signal frequency impose restrictions on the input current of the inductor. Erkan Yuce was born in 1969 in Nigde, Turkey. He received the B.Sc. degree from Middle East Technical University and M.Sc. degree from Pamukkale University in 1994 and 1998 respectively, all in Electrical and Electronics Engineering. He is currently Research Assistant and a Ph.D. student at the Electrical and Electronics Engineering Department of Bogazici University. His current research interests include analog circuits, active filters, synthetic inductors, voltage-mode current-mode circuits. He is the author or co-author of about 4 papers published in scientific journals or conference proceedings Oguzhan Cicekogluwas born in 1963 in Istanbul, Turkey. He received the B.Sc. and M.Sc. degrees from Bogazici University and the Ph.D. degree from Istanbul Technical University all in Electrical and Electronics Engineering in 1985, 1988 and 1996 respectively. He served as lecturer at the School of Advanced Vocational Studies Electronics Prog. of Bogazici University where he held various administrative positions between 1993 and 1999, and as part time lecturer at various institutions. He was with Biomedical Engineering Institute between 1999 and 2001. He is currently Associate Professor at the Electrical and Electronics Engineering Department of Bogazici University. His current research interests include analog circuits, active filters, analog signal processing applications and current-mode circuits. He is the author or co-author of about 150 papers published in scientific journals or conference proceedings. Oguzhan Cicekoglu is a member of the IEEE.     

Symbolic analysis of analog circuits containing voltage mirrors and current mirrors

The pathological elements voltage mirror (VM) and current mirror (CM) have shown advantages in analog behavioral modeling and circuit synthesis, where many nullor-mirror equivalences have been explored to design and to transform voltage-mode circuits to current-mode ones and viceversa. However, both the VM and CM have not equivalents to perform automatic symbolic circuit analysis. In this manner, we introduce nullor-equivalents for these pathological elements allowing to include parasitics and to perform only symbolic nodal analysis. The nullor-equivalent of the CM is extended to provide multiple-outpus (MO-CM). Finally, two active filters containing VMs, CMs and MO-CMs are analysed to show the usefulness of the models.     

基于控阈技术的四值电流型CMOS电路设计

以开关信号理论为指导,对电流型CMOS电路中如何实现阈值控制进行了研究.建立了实现阈值控制电路的电流传输开关运算.在此基础上,设计了具有阈值控制功能的电流型CMOS四值比较器、全加器及锁存器等电路.通过对开关单元实施阈值控制后,所设计的电路在结构上得到了非常明显的简化,在性能上也获得了优化.PSPICE模拟验证了所提出的电路具有正确的逻辑功能并且较之以往设计具有更好的瞬态特性和更低的功耗.     

CMOS analogue median circuit

Median filters are very important nonlinear filters, finding many applications in image and speech processing. A novel CMOS analogue median circuit is proposed with a design that employs a combination of current-mode circuits such as a current absolute value circuit and a current minimum circuit     

New universal biquad filters using only two unity-gain cells

New current-mode and voltage-mode universal biquad filters are presented using only two unity-gain cells (one current follower and one voltage follower) in each configuration. The proposed filters employ one less follower than in the literature to date. The filters can realize highpass, bandpass, lowpass, notch and allpass responses without any changes in the circuit topology. The circuits enjoy the following advantages: minimum number of active elements, no component-matching condition and low active and passive sensitivities.     

Novel universal current-mode filters using unity-gain cells

Two novel universal current-mode filters using unity-gain current followers (CFs) and voltage followers (VFs) are presented. The first one, employing three CFs, one VF, two grounded capacitors and two resistors, has two inputs and three outputs. The second one, employing only two CFs, one VF, two grounded capacitors and two resistors, has four inputs and a single output. Both proposed circuits oOEer the following advantageous features: universal current-mode filter realization from the same configuration, no requirements of component matching conditions, employment of two grounded capacitors ideal for integration, employment of two virtually grounded resistors good for voltage control, easy adjustment of ω₀/Q and ω₀ through separate virtually grounded resistors and low active and passive sensitivity performance.     

Current-mode CMOS integrated circuits for analog computation and signal processing: A tutorial

This paper presents an overview of design techniques for a broad range of current-mode analog integrated circuits implemented in CMOS technology at a tutorial level. Primarily, emphasis is placed on circuit configurations, first-order analysis, and approximate design equations for analog integrated circuits operating in current domain for signal computation and processing applications.     

基于控阈技术的电流型CMOS全加器的通用设计方法

利用电流信号的阈值易于控制这一特点,对电流型CMOS电路中如何实现阈值控制进行了研究.以开关信号理论为指导,建立了实现阈值控制电路的电流传输开关运算并具体指导设计了具有阈值控制功能的二值和多值电流型CMOS全加器.提出了适用于任意逻辑值的可控阈电流型CMOS全加器的通用设计方法.通过对开关单元实施阈值控制后,所设计的电路在结构上得到了非常明显的简化,在性能上也获得了改善.最后给出了采用0.25μm CMOS工艺参数的HSPICE模拟结果及其能耗比较.     

Design of positive feedback driven current-mode amplifiers Z-Copy CDBA and CDTA,and filter applications

In this study, high-performance current-mode amplifiers Z-Copy current differencing buffered amplifier (ZC-CDBA) and current differencing trans-conductance amplifier (ZC-CDTA) are designed. In order to improve input impedances of the amplifiers, a new approach based on positive feedback is proposed. Impedance improvement/reduction is achieved by using only two extra transistors for each input. This number of extra transistors is very few compared to that in conventional negative feedback based improvement techniques. The proposed technique is justified by performing a detailed stability analysis. It is shown that the input impedances of ZC-CDBA and ZC-CDTA can be safely reduced to the level of 50 Ω by considering fabrication scatterings. The proposed amplifiers are verified with analog filter applications, a new KHN and recently proposed biquadratic and frequency agile filters. It is shown that the filters operate accurately at the frequency level of 100 MHz. This is a clear sign of the proposed amplifiers’ high performance. Layout and post layout simulations are done for the proposed circuits using AMS 0.18 µm parameters in Cadence environment.     

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.     

Current-mode CMOS multiple-valued logic circuits

Current-mode CMOS circuits are receiving increasing attention. Current-mode CMOS multiple-valued logic circuits are interesting and may have applications in digital signal processing and computing. In this paper we review several of the current-mode CMOS multiple-valued logic (MVL) circuits that we have studied over the past decade. These circuits include a simple current threshold comparator, current-mode MVL encoders and decoders, current-mode quaternary threshold logic full adders (QFAs), current-mode MVL latches, current-mode latched QFA circuits, and current-mode analog-to-quaternary converter circuits. Each of these circuits is presented and its performance described     

Using nullors for realisation of current-mode FTFN-based inversefilters

The authors present a general procedure for the realisation of current-mode four-terminal floating nullor (FTFN)-based inverse filters from the well-developed voltage-mode filters using nullors. Each of the derived filters possesses an inverse transfer function identical to that of the original voltage-mode filter without the need for any matching conditions. The cascadability characteristics of the original circuits have been further investigated. This procedure is expected to be a convenient method for generating current-mode inverse filters     

具有快速动态响应的高稳定性电流型降压DC-DC转换器

提出了一种高稳定性的电流型DC-DC转换器.首先应用一种新型的电流型转换器的模型推导了控制环路的增益表达式,在分析其环路增益的基础上,提出了一种新颖的控制环路频率补偿的方法,从而使转换器的稳定性不受负载电流和电源电压变化的影响.其次应用这种新的频率补偿方法,使用0.5μm-CMOS工艺设计了一种电流模式的降压型转换器.仿真结果表明,该稳压器具有高度的稳定特性,其稳定性与负载和电源电压无关.并且由于这种新的频率补偿为环路提供了极高的带宽,所以该转换器具有优异的动态响应.其提供的全负载瞬态响应的建立时间小于5μs,过冲电压小于30mV.     

Systematic Generation of Current-Mode Linear Transformation Filters Based on Multiple Output CCIIs

A transformation called current-mode linear transformation (CMLT) and its filter applications using multiple output second-generation current conveyors (MOCCIIs) are presented. The systematic method is developed to realize CMLT MOCCII-based filters efficiently. Based on the proposed design tables, we can synthesize high-order current-mode all-pole and elliptic filters with MOCCIIs, grounded resistors and capacitors. Moreover, the high-frequency elliptic filter can also be efficiently realized by adding capacitors to the relative all-pole filter, although floating capacitors are needed. Third-order Chebychev and elliptic lowpass filters are described in this paper. Experimental results that confirm the theoretical analysis are obtained. Furthermore, the proposed circuits can be extended to higher-order filters.     

Novel cascadable current-mode first order all-pass sections

This paper presents some new current mode first order all-pass sections with grounded components employing a modified current conveyor. The new circuits are ideal for current-mode cascading by possessing high output impedance. As an application of the circuits, a new quadrature oscillator is also given. The theory is validated through PSPICE simulation using 0.5μ CMOS parameters.     

Use of nano-scale double-gate MOSFETs in low-power tunable current mode analog circuits

Use of independently-driven nano-scale double gate (DG) MOSFETs for low-power analog circuits is emphasized and illustrated. In independent drive configuration, the top gate response of DG-MOSFETs can be altered by application of a control voltage on the bottom gate. We show that this could be a powerful method to conveniently tune the response of conventional CMOS analog circuits especially for current-mode design. Several examples of such circuits, including current mirrors, a differential current amplifier and differential integrators are illustrated and their performance gauged using TCAD simulations. The topologies and biasing schemes explored here show how the nano-scale DG-MOSFETs may pave way for efficient, mismatch-tolerant and smaller circuits with tunable characteristics.