多通OTA有源滤波器

本文提出一种用跨导运算放大器(OTA)和电容实现的状态变量滤波器。它具有在同一输入条件下,同时输出高通、低通、带通和带阻等滤波函数的特点,并且滤波器的中心频率ω_0,品质因子Q和增益因子K可独立调节,易于单片集成。已用计算机SPICEⅡ程序对所设计的OTA滤波器电路进行了模拟,结果与设计完全一致。     

一种新颖的OTA结构的数模转换器

介绍了一种新颖结构的数模转换器，此转换器的设计核心是采用跨导运算技术，由CMOS运算跨导放大器（OTA）构成。此D／A转换器以模拟电流作为主要信号变量，以跨导运算放大器取代电压运算放大器，以基于OTA的有源元件取代部分无源元件，通过改变OTA的偏置电流，从而改变其互导增益gm和电压放大器增益Au，更适合于IC的集成。采用9个OTA构成一个8位的加法电路，8个OTA的互导增益gm对应8位的数字信号，8个MOS管作为开关运用由8位的数字信号控制，从而实现数字信号到模拟信号的转换。     

非理想第二类电流传送器及其应用

本文定义了一种非理想第二类电流传送器(NCCII);给出了用跨导运算放大器(OTA)实现NCCII的电路;讨论了用该电路实现的电容和电阻变换器。     

一种改善CMOSOTA线性度的实现电路

为了满足低电压、低功耗跨导放大器-电容(OTA-C)连续时间型高频模拟集成滤波器结构中,跨导放大器(ITA)对线性度的要求,基于交叉耦合差分对MOS管结构中典型OTA电路的非线性特性进行研究,得到其非线性失真项.据此,提出一种基于前馈线性化原理改善OTA线性度的实现电路,给出线性化处理前后OTA传输特性的对比曲线.结果表明,通过改变结构,提高了OTA的线性度.     

密勒运算跨导放大器的单粒子瞬变效应分析

从2阶闭环系统的角度出发,推导并分析了单粒子瞬变(SET)电流在密勒运算跨导放大器(OTA)中的传导效应。通过理论分析,发现OTA两级跨导比例(Gm2/Gm1)的大小不仅决定了系统闭环的稳定性,也决定了SET电流在系统输出端电压响应的振动幅度和恢复时间。在标准0.18μm CMOS工艺下,通过改变两级跨导的比例值,对电路的两个有效节点进行电路级SET轰击实验,收集实验结果,给出抗SET效应运算放大器的设计建议。     

基于OTA的通用双二阶滤波器设计

在跨导运算放大器（OTA,Operational Transconductance Amplifier）器件特性的基础上,提出了一种采用OTA构成的电压模式三输入单输出通用双二阶滤波电路,该电路由4个OTA、2个电容构成。通过选择不同的输入端口,它可以实现二阶低通、带通、高通、陷波、全通5种滤波功能,通过分析该电路的传输函数可知,该电路的灵敏度低,对该电路用PSPICE进行了仿真,仿真结果表明该电路设计正确。     

跨导型运算放大器NE5517应用

<正> 我们通常见到的运算放大器电路,都是围绕电压输入一电压输出的常规型运放而设计的。而另一种类型的运放也常用于很多音频处理场合中,它采用电压输入→电流输出(跨导)形式工作,增益由外接控制端控制,这种器件称作跨导型运算放大器(OTA),NE5517就是一款这样的集成电路。图1为 OTA 的电路符号和工作时     

低电压高线性度宽输入范围Gm-C滤波器实现

本文采用低电压高线性度宽输入范围跨导运算放大器设计实现四阶Chebyshev低通滤波器,对所设计的四阶Chebyshev传输函数应用两个双二次节Gm-C滤波单元元级联实现,3．3V电源电压的全差分跨导运算放大器在1V输入信号范围内Gm值的线性度波动小于0．5％,0．5μmCMOS工艺MOS管级的计算机仿真结果表明所提出的电路方案正确有效,适于全集成。     

基于新型可调谐高线性OTA的高阶滤波器设计

基于交叉耦合的原理提出了一种高线性可调谐的OTA(跨导运算放大器),并以它为基本部件设计了一个巴特沃思(Butterworth)七阶滤波器。OTA的增益可以通过调节独立外接电源进行控制。基于新型OTA的高阶滤波器电路结构简单,无源器件接地,容易集成。     

二极管型非制冷红外探测器的前端电路设计

设计了一种二极管型非制冷红外探测器的前端电路,该电路采用Gm-C-OP积分放大器的结构,将探测器输出的微弱电压信号经跨导放大器(OTA)转化为电流信号,再经电容反馈跨阻放大器(CTIA)积分转化为电压信号输出。该OTA采用电流反馈型结构,可以获得比传统OTA更高的线性度和跨导值。输入采用差分结构,可以有效地消除环境温度及制造工艺对探测器输出信号的影响。电路采用0.35 m CMOS工艺进行设计并流片,5 V电源电压供电。Gm-C-OP积分放大器总面积0.012 6 mm2,当输入差分电压为0~5 mV时,测试结果表明:OTA跨导值与仿真结果保持一致,Gm-C-OP积分放大器可实现对动态输入差分信号到输出电压的线性转化,线性度达97%,输出范围大于2 V。     

Novel current-mode active-only biquad with loss-less and lossy integrators

This paper presents a realization of a current-mode active-only biquad with a two-integrator loop structure. The proposed circuit is constructed solely with operational amplifiers (OAs) and operational transconductance amplifiers (OTAs). The circuit can realize low-pass, band-pass, high-pass, band-stop and all-pass transfer functions, and the circuit characteristics can be electronically tuned by adjusting the transconductance gains of the OTAs. An example is given together with simulated results by PSPICE. The circuit configuration is very suitable for implementation in both bipolar and CMOS technologies.     

Novel voltage-mode biquad without external passive elements

This paper introduces a voltage-mode biquad filter using only active devices such as operational amplifiers and operational transconductance amplifiers (OTAs). The circuit configuration is obtained from Soderstrand's active-R state variable filter as a prototype. The proposed circuit can realize five different biquad transfer functions, and the circuit characteristics can be electronically tuned by adjusting the transconductance gains of the OTAs. An example is given, together with simulated results by PSPICE. The circuit configuration is very suitable for implementation in both bipolar and CMOS technologies.     

Voltage-mode active-only biquad

This paper presents a realization of a voltage-mode active-only biquadratic circuit. The proposed circuit is constructed employing solely operational amplifiers and operational transconductance amplifiers (OTAs). The circuit configuration is obtained from a second-order structure with two integrator loops. The circuit can realize low-pass, band-pass, high-pass, band-stop, low-pass notch, high-pass notch and all-pass transfer functions by suitably choosing the input and output terminals, and the circuit characteristics can be electronically tuned through adjusting the transconductance gains of OTAs. Some examples are given together with simulated results by PSPICE. The circuit configuration is very suitable for implementation in both bipolar or CMOS technologies.     

Versatile voltage-mode active-only biquad with lossless and lossy integrator loop

This paper presents a realization of a voltage-mode active-only biquad using operational amplifiers (OAs) and operational transconductance amplifiers (OTAs). The circuit configuration is obtained from a second-order integrator loop structure with lossless and lossy integrators. The proposed circuit can realize low-pass, band-pass, high-pass, band-stop and all-pass transfer functions by a suitable choice of input and output terminals. The circuit characteristics can be electronically tuned through adjustment of the transconductance gains of the OTAs. An example is given, together with simulated results by PSPICE. The circuit configuration is very suitable for implementation in both bipolar and CMOS technologies.     

Current-mode biquad using OTAs and CF

A novel current-mode biquad using operational transconductance amplifiers (OTAs) and current follower (CF) is presented. The circuit can realise lowpass, bandpass, highpass, band-stop and all-pass transfer functions without any circuit matching conditions. The circuit parameters can also be tuned independently by the transconductance gains of the OTAs. The proposed biquad enjoys very low sensitivities with respect to the circuit elements.     

Novel grounded and floating high order immittance simulators using OTAs and OAs

This paper proposes novel grounded and floating high order series and parallel immittance simulators using operational transconductance amplifiers (OTAs) and operational amplifiers (OAs) with a finite gain–bandwidth (GB) product. They are composed of active devices (OTAs and OAs) and resistances, and are suitable for monolithic implementation in either CMOS or bipolar technologies. They also realize both positive and negative high order immittances. The circuit characteristics can be electronically tuned by adjusting the transconductances of OTAs and the GB products of OAs. Any transfer functions are realizable using the proposed simulators. Two examples are shown, together with simulation results.     

Electronically tunable current-mode active-only biquadratic filter

This paper presents a realization of current-mode active-only filter. The proposed filter is constructed employing operational amplifiers and operational transconductance amplifiers (OTAs). The circuit can realize biquadratic transfer function, and the circuit characteristics can be electronically tuned through adjusting the transconductance gains of the OTAs. An example is given together with simulated result by PSPICE. The circuit configuration is very suitable for implementation in both bipolar or CMOS technologies.     

Versatile active-only biquad circuits with loss-less and lossy integrators

This paper presents a realization of voltage-mode and current-mode active-only biquad circuits with a two-integrator loop-structure. The circuits are constructed solely with operational amplifiers (OAs) and operational transconductance amplifiers (OTAs). The biquad circuits can realize the multiple circuit transfer functions, and the circuit parameters can be tuned orthogonally through adjusting the transconductance gains of the OTAs. Also, these biquad circuits enjoy very low sensitivities with respect to the circuit active elements. Some examples are given together with simulated results by PSPICE.

The circuit configurations are very suitable for implementation on both bipolar and CMOS technologies.     

Instrumentation amplifiers using operational transconductance amplifiers

Instrumentation amplifier circuits using operational transconductance amplifiers (OTAs) as active circuit elements are proposed in this paper. Two new instrumentation amplifier circuits have been described and experimentally verified, where the first circuit comprises four OTAs and five resistors and the second circuit comprises two OTAs and three resistors.     

Note on two integrator loop OTA-C configurations

A two integrator loop structure with six operational transconductance amplifiers (OTAs) and two capacitors has been proposed by Sanchez-Sinencio, et al. (1988). However, the filter functions which can be provided by this general architecture have not been available to date, although its special four OTA and two OTA derivatives have been studied. It is demonstrated that this circuit, with voltages applied to the input terminals of the OTAs inside the loops and output voltages from the circuit nodes inside the loops, offers many very useful and interesting functions such as LP, BP, HP, BS, LPN, HPN and AP without using floating capacitors, coefficient difference nulling and additional OTAs. Other existing two integrator loop structures cannot offer all the functions under similar conditions