A new approach for high-input impedance in voltage mode filters using first-generation current conveyor in place of second-generation current conveyor

An advantage of the second-generation current conveyor (CCII) over the first-generation current conveyor (CCI) is its high-input impedance Y terminal. Thus, CCII offers cascadable voltage mode filter realisations with little efforts. However, in case of CCI this feature is difficult to achieve. This article presents a case where the CCI is able to provide cascadability for some voltage mode filter topologies, where the CCII is not. The presented approach is applied to some filter circuits from the literature and new circuits are derived with cascadability feature. Simulations are performed to verify the theoretical results.     

Implementation of reconfigurable nth-order filter based on CCII

Topologies for realizing voltage and current mode reconfigurable nth-order filters based on the second-generation current conveyor (CCII) are assessed. The most compatible structure for field-programmable analog array is identified. A CCII adopting active current division networks are utilized for implementing the proposed filter leading to wide control of its coefficients. Programmability characteristics are demonstrated through experimental results obtained from integrated circuit chips fabricated in a 0.18 μm CMOS process.     

A very compact, 0.4 V DTMOS CCII employed in an audio-frequency filter

This paper presents an ultra low-voltage, ultra low-power, very compact, dynamic threshold voltage MOS transistor (DTMOS)-based CCII circuit. The proposed circuit is capable of operating under ± 0.2 V symmetric supply voltages. The circuit topology is very compact and consists of only four DTMOS transistors and four ordinary NMOS transistors. The total power consumption of the circuit is found as only 214 nW while all transistors are working in the subthreshold region. The current conveyor has 570 kHz 3 dB-bandwidth from X to Y terminal for the voltage gain and has low, 0.2 % following error between these terminals for inputs not exceeding ± 60 mV. TSMC 0.18 µm process technology parameters are used in the design of the proposed CCII block which is then employed in an audio-frequency, second-order, band-pass filter configuration where real speech signals are fed to the input of the filter to further investigate its characteristics. Close agreement is found between theoretical study and simulated responses.     

Universal filter using plus-type CCIIs

A universal second-order filter circuit with voltage gain using only plus-type current conveyors (CCIIs) is presented. The circuit offers several advantages, such as high input impedance, low filter sensitivities to passive elements, use of grounded capacitors and independent control of ω₀, Q and voltage gain with separate grounded resistors. The use of only one type (plus-type or minus-type) of CCII simplifies the configuration     

基于开关电流技术的切比雪夫滤波电路的实现

提出了一种运用开关电流技术实现切比雪夫低通滤波电路的方法。将双二次滤波器的传递函数由s域进双线性z变换,确立了基于开关电流积分器的双二次节电路,利用这种双二次节可以实现开关电流滤波器。文中采用双二次低通滤波器级联实现了六阶切比雪夫低通滤波器的设计与仿真,仿真结果表明切比雪夫低通滤波器的陡峭衰减特性和理想幅频特性符合设计要求,从而证实了该方法的可行性和正确性。     

CMOS inverters based positive type second generation current conveyor

A new versatile class AB low-voltage second generation current conveyor based on CMOS inverters operating in transconductance mode is presented in this letter. Against traditional design based on CCII+, the circuit is able to operate at low supply voltages and offers numerous advantages like class AB operation, large voltage and current swing, synthesis from digital inverters. Simulation results from a typical 0.35 μm CMOS process had demonstrated the circuit capability to operate at high frequency over wide voltage and wide current swings. The proposed circuit operation has been acted from measurements with the HEF4069UBP from Philips semiconductors [1].     

基于OTRA电流模式二阶通用滤波器的设计

鉴于单个OTRA电流模式滤波器未见报道,以CCⅡ二阶通用电流模式滤波器为原型,利用1个OTRA,1个MOS电压跟随器,1个CMOS电压反相器,3个电阻和2个电容,构成了二阶通用电流模式滤波器,可同时获得高通、带通和低通输出。与传统电路相比,该电路能减小寄生电容的影响,因而有较高的稳定性;调节极点角频率与品质因素的元素多,因而调整方便,且通带增益可调范围广,无源灵敏度较低,电路结构简单,便于电控调谐,特别适合单片集成技术。     

Universal filter with three inputs using CCII+

A voltage-mode universal filter with three inputs and one output using only plus-type current conveyors (CCII+) is presented. This circuit uses three CCII+s, three resistors and a minimum number of capacitors. It has low sensitivity, low output impedance and low component spread. The use of only CCII+s simplifies the configuration     

Towards a Perfect CMOS CCII

DC offset and inaccurate voltage follower action betweenterminals Y and X, the relatively highimpedance seen at terminal X and inaccurate currentfollower action between terminals X and Zplague simple circuit realizations of the CCII. This paper summarizesthe methods employed and compares the improvement of the CCIIcharacteristics achieved by a variety of published circuits,with emphasis laid on CMOS realizations. In these comparisons,the conventionally employed but inaccurate current mirror outputstages were replaced by a circuit employing current isolationand thereby providing accurate current follower action betweenterminals X and Z. Furthermore, twonovel realizations of a differential CCII – basedtransconductance amplifier are described, which can also be employedas input stage of an instrumentation voltage amplifier exhibitingan exceptionally high CMRR and excellent frequency response.Finally, a current fan out circuit for cascode CCII –swill be introduced, whose transfer function value is electronicallyadjustable.     

Realization of current-mode biquadratic filter employing multiple output OTAs and MO-CCII

This paper presents a low voltage low power operational transconductance amplifier circuit. By using a source degeneration technique, the proposed realization powered at ±0.9 V shows a high DC gain of 63 dB with a unity gain frequency at 3.5 MHz, a wide dynamic range and a total harmonic distortion of −60 dB at 1 MHz for an input of 1 Vpp. According to the connection of negative current terminal to positive voltage terminal of double output OTA circuit, a second generation current conveyor (CCII-) has been realized. This circuit offers a good linearity over the dynamic range, an excellent accuracy and wide current mode of 56 MHz and voltage mode of 16.78 MHz cut-off frequency f-3 dB.Thereafter, new SIMO current-mode biquadratic filter composed by OTA and CCII as active elements and two grounded capacitors is implemented. This filter is characterized by (i) independent adjusting of pole frequency and quality factor, (ii) it can realize all simulations results without changing the circuit topology, (iii) it shows low power consumption about 0.24 mW. All simulations are performed by Cadence (Cadence Design Systems) technology Tower Jazz 0.18 μm TS18SL.     

电流模式带通滤波器设计

随着电子技术的发展,电流模式电路也越来越受到人们的关注,尤其是CCII(第二代电流传输器),本文针对以往电路过于复杂的特点,利用CCII(第二代电流传输器)设计基于单个CCII的带通滤波器电路,该电路仅使用一个CCII和几个R,C元件,与同类电路相比,该电路结构简单,且具有更低的无源灵敏度。     

电流模集成电抗元件与频率变换电路的设计

为了拓宽电流模单元电路结构在低压低功耗射频集成电路中的应用,研究把第二代电流传输器用作电抗器件和频率变换电路。以第二代电流传输器为核心,辅助予外围电路,构造从输入到输出端口不同性质传输阻抗的有源电容倍增器和有源电感,并且基于第二代电流传输器组合结构差异的分析,设计了集成频率变换电路。从理论上,推出有源电容倍增器和有源电感结构的合理性。仿真集成频率变换电路,结果袁明对40MHz以下正弦波倍频功能正确,且以100kHz正弦波为调制信号和以10MHz的正弦波为载波获得了双边带调幅信号。这为射频集成电路设计提供了新的思路。     

CCII-Based Continuous-Time Current-Mode Biquad Filter

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A single current conveyor-based low voltage low power bootstrap circuit for ElectroCardioGraphy and ElectroEncephaloGraphy acquisition systems

In this letter we propose a novel low voltage and low power single-CCII bootstrap circuit specifically designed to be implemented as input stage in ElectroCardioGraphy (ECG) or ElectroEncephaloGraphy (EEG) acquisition systems. The proposed circuit implements only a second generation current conveyor that has been designed to obtain, at X and Z nodes, reduced parasitic impedances, so improving CCII performance. Moreover, simulation results are also presented for a two electrodes ECG system. The circuit, designed in a standard 0.35 μm CMOS technology, shows low voltage (1.5 V) low power (28 μW) characteristics, so it is particularly suitable for portable applications.     

一种基于OTA和CCII实现的n阶低通滤波器

提出了用信号流图法设计n阶基于OTA（跨导运算放大器）和CCII（第二代电流传输器）电流模式低通滤波器的方法。该滤波器由具有双输出端的平衡滤波器和第二代电流传输器及接地电容构成。与同类电路比较,设计更简便,结构更简单,无源元件全部接地,易于集成。     

基于石墨烯探测器的积分电路设计

为了解决石墨烯探测器光电探测的难题,针对石墨烯探测器受光照像元电阻发生变化的特点,设计了基于石墨烯探测器的新型积分电路结构。该积分电路结构主要包含前端偏置电路、运算放大器以及开关和反馈电容等部分,电路主要利用暗像元电阻不随光照变化,而感光像元电阻会随光照强度变化而变化的特点,将光照条件下暗像元支路的电流与感光像元支路电流的差作为光响应电流,并采用CTIA积分电路进行电流积分,将光响应电流转换为积分电压输出,进而实现石墨烯探测器对光响应信号的探测和输出。文中对相关的主要电路设计进行了分析,并基于Cadence ADE仿真环境完成了电路仿真。经仿真分析,基于文中的积分电路,可以将不同光照条件下石墨烯探测器的光响应转换为对应的积分电压输出。可见,所设计的积分电路能够满足石墨烯探测器对光响应探测的需求,对石墨烯材料进入光电探测器领域具有重要意义。     

Single CCII-based voltage-mode universal filter

A new voltage-mode universal biquad filter is presented which can realize all the five standard filter functions namely lowpass, bandpass, highpass, notch, and allpass employing only one CCII as active element. The new circuit is composed of only one CCII, two capacitors, and three resistors, and realizes five generic filter signals without any inverting-type voltage input signals. This is unlike biquad reported by filter structures which employs more active components and needed an inverting-type voltage input signal to realize allpass signal.     

用CCII回转器设计梯形结构电流模式滤波器

该文提出一种设计高阶CCⅡ(第二代电流传输器)电流模式滤波器的新方法,即用CCⅡ回转器综合电流模式无源梯形网络的输入导纳,从而设计出高阶电流模式CCⅡ滤波器。用该方法设计出的电路与其它同类电路比较,电路结构简单、所使用的CCⅡ数目少。文中对CCⅡ的非理想特性进行了分析,提出了对CCⅡ的非理想特性进行补偿的方案。文中给出了六阶巴特沃斯滤波器的设计举例及补偿前和补偿后的计算机PSPICE仿真结果。     

基于第二代电流传输器的二阶带通滤波器设计

设计了一种单端输入单端输出的电流模式带通滤波器,核心部件为用三极管设计的第二代电流传输器（CCⅡ）.电路由两个CCⅡ和一些无源器件构成,通过偏置电流控制其中心频率,实现对信号的带通滤波功能.该滤波器提供了更大带宽下的更高电压增益,解决了电压跟随不理想的问题,且具有更低的无源灵敏度,能广泛应用于无线通讯、射频等高频模拟电路中.使用Hspice软件仿真分析并验证了理论设计的准确性和可行性.     

基于电调谐DOCCII的电流模式连续时间滤波器

本文提出了基于可变电流增益双输出CCII(DOCCII)的电流模式N阶低通滤波器和通用滤波器,并给出了N阶通用滤波器的一个通用表达式。所给出的滤波器参数可以通过DOCCII的可变电流增益因子独立调谐,并且结构简单,所有无源元件均接地,便于集成。