Four new oscillators using operational transresistance amplifier

In this paper, four new sinusoidal waveform generators based on the operational transresistance amplifier (OTRA) are presented. The first proposed circuit is a minimum component RC sinusoidal oscillator circuit with one OTRA and a few passive components. The second and third proposed circuits consist of one OTRA and a few passive components, among them two passive components are connected to ground. These circuits are able to control the condition of oscillation and frequency of oscillation independently. The fourth proposed quadrature oscillator circuit uses two OTRAs as main active building blocks and a few external passive components to generate the oscillations. The IC AD844AN is adopted to implement the proposed circuits on a laboratory breadboard with external passive components. Both the SPICE simulation and experimental results are given to verify the theoretical analysis of the proposed circuits.     

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。     

A Novel Single-Resistance-Controlled Sinusoidal Oscillator Employing Single Operational Transresistance Amplifier

A novel operational transresistance amplifier (OTRA)-based single-resistance-controlled sinusoidal oscillator (SRCO) is proposed. It uses single OTRA, three resistors and two capacitors. To the best knowledge of author, this is the first oscillator constructed with single OTRA. The oscillator circuit provides independent control of oscillation frequency without disturbing oscillation condition by a resistor. It has also low passive sensitivities. The oscillator circuit is insensitive to parasitic input capacitances and input resistances due to zero internally grounded input terminals of OTRA. PSPICE simulations are given to verify the theoretical analysis.     

RC active network synthesis using an amplifier†

A new RC active network synthesis procedure for realizing a given open-circuit voltage transfer function is presented. The interconnection of an ideal voltage amplifier of gain greater than unity and two RC sub-networks in a grounded 2-port configuration is considered for this purpose. It is shown that a general rational transfer function of any order can be realized by such a configuration, provided the transfer function does not have zeros on the positive real axis of the s plane. The method compares favourably with other active RC synthesis procedures using a single finite-gain amplifier.     

任意阶OTA-C多功能滤波器的设计。

提出了一种新的任意阶运算跨导放大器——电容(OTA-C)多功能滤波器的设计方法。通过将n阶传递函数分解为n+1个一阶传递函数,导出了任意阶传递函数OTA-C实现电路。适当选择各输入端电压,可实现低通、高通、带通、带阻、全通等滤波功能。文中给出了6阶滤波器设计实例,PSPICE仿真结果与理论分析相吻合,验证了设计方法的可行性。     

Active RC synthesis of a narrow band transfer function using Yanagisawa scheme

Synthesis of active RC networks has become very important with the advent of integrated circuits. But for all such networks the stability and sensitivity consideration are very important. Particularly in the case of a narrow band filter design, the stability consideration becomes crucial because of the proximity of the poles to the imaginary axis. Here it haa been shown that for a second order narrow band transfer function using Yanagisawa scheme for synthesis, stability can be maximized by choosing the arbitrary poles of the RC network in a particular manner. For this particular choice of the poles the root sensitivities with respect to each element of the synthesized network have been considered. From these sensitivity considerations, the variable elements have been chosen for the control of the location of poles. This basic second order module has been used for the realization of higher order transfer functions. The technique has been illustrated by designing an eighth order narrow band transfer function useful for the intermediate frequency stage of broadcast receivers.     

Transimpedance Type Fully Integrated Biquadratic Filters Using Operational Transresistance Amplifiers

Operational transresistance amplifier (OTRA) is an inherently suitable active building block for transimpedance type signal processing because of its current input/voltage output nature. It is due to the fact that both input and output terminals of OTRA are characterized by low impedance. In this paper, we present an OTRA based transimpedance type biquadratic filter configuration. It realizes all five different filtering functions, namely low-pass, high-pass, band-pass, notch and all-pass. The configuration can be made fully integrated based on MOS-C realization by making use of current differencing and internally grounded inputs of OTRA.     

Novel allpass filter configuration employing single OTRA

A new circuit configuration uses a single operational transresistance amplifier (OTRA) and four passive elements to realize both first- and second-order allpass filters. Owing to internal grounding of the OTRA input terminals, effects of input parasitics are significantly reduced. Applications of the circuit include the realization of the phase equalizer, the quadrature oscillator, and the high-Q bandpass filter for analog signal processing. The performance of the allpass filter is illustrated by circuit-level simulation of a quadrature oscillator with CMOS realization of the OTRA.     

Equal-valued grounded-capacitor active RC realisation of all-pole transfer functions

An active RC structure with equal-valued grounded-capacitors and employing, at the most, two amplifiers is proposed for realising an all-pole transfer function of any order. Such a structure is attractive for integrated-circuit fabrication.     

Nth-order allpass voltage transfer function synthesis using CCII+s:signal-flow graph approach

A general synthesis method is given for the realisation of an nth-order allpass voltage transfer function by the active RC circuit containing a minimum number of capacitors and at most n+1 current conveyors. All the current conveyors are positive, and n of them act as voltage followers. This makes the proposed circuit simple and attractive     

Novel Transimpedance Type First-Order All-Pass Filter Using Single Otra

A novel transimpedance-mode first-order all-pass filter configuration is proposed. It uses a single operational transresistance amplifier (OTRA) and few passive components. The proposed circuit is structurally all-pass that does not impose any component matching condition. The proposed circuit is insensitive to parasitic input capacitances and input resistances due to the internally grounded input terminals of the OTRA. It provides an alternative realization of phase equalizers for analog signal processing applications by providing also current-to-voltage conversion. The theoretical results are verified with PSPICE simulations using a CMOS realization of OTRA.     

Sensitivity minimum in active transfer function synthesis

A formula for Schoeffler's sensitivity criterion is developed and used to prove the existence of a sensitivity minimum in an active RC transfer function synthesis procedure.     

New realization of third order sinusoidal oscillator using single OTRA

In this paper, a new, single operational transresistance amplifier (OTRA) based third order sinusoidal oscillator is presented. The nonideal behavior of proposed structure has been analyzed using single and double pole models of the OTRA. It is observed that for high-frequency applications the effect of nonidealities may be eliminated through self-compensation. Active and passive sensitivities are computed for the proposed structure and are found to be less than unity rendering proposed circuit insensitive to component variations. Workability of the proposed oscillator is verified through Analog Design Environment (ADE) spectre tool provided by cadence virtuoso using 0.18 μm CMOS process parameters. Monte Carlo analysis is also carried for the proposed structure. Total harmonic distortion (THD) is found to be less than 2.6%. Post layout simulations; experimental results are also included to validate the theory.     

Transfer function synthesis using a finite-gain amplifier

An active RC circuit employing a single finite–gain amplifier, one two–port and two ono–ports, has been presented here for the realization of n general voltage transfer function without positive real axis zeros. The comparative merits of the scheme with respect to that proposed by Rao (1969) are that the synthesis procedure is simpler and the number of passive circuit elements required is smaller. The coefficient of realization of the synthesized transfer function can always be made equal to unity with the scheme. A few examples are included to illustrate the synthesis procedure.     

Nth-order lowpass voltage transfer function synthesis using CCII+s:signal-flow graph approach

A general synthesis method is given for the realisation of an nth-order lowpass voltage transfer function, using the active RC circuit containing a minimum number of capacitors and n+1 current conveyors at most. All the current conveyors are of the noninverting type, and they act as voltage followers. This makes the proposed circuit simple and attractive     

Design and analysis of a high speed double-tail comparator with isomorphic latch-preamplifier pairs and tail bootstrapping

In this paper, a new grounded positive lossless frequency dependent negative resistance (FDNR) simulator and two of its applications are presented. The proposed FDNR uses single OTRA and requires five number of passive components; two resistances and three capacitances. The workability of the proposed simulator is demonstrated through the realization of a single resistance controlled oscillator (SRCO) and a fifth order elliptic filter. A detail non-ideality analysis is also done for both FDNR and SRCO. In addition the sensitivity, non-ideality effect and frequency stability analysis of SRCO have been presented. Monte Carlo simulation of the SRCO output has been given and discussed. Moreover, the layout of OTRA, FDNR and SRCO and their post layout simulations in 180 nm are given. PSPICE simulation and experimental results are included to verify theory.     

Synthesis of an arbitrary transfer function matrix using RC and one-ports and operational amplifiers†

Synthesis of multi-port networks is attracting increasing attention in network theory. On the other hand comparatively little work has been reported on active RC multi-port transfer function synthesis. This paper presents an elegant synthesis procedure to realize any arbitrary rational m×n open-circuit voltage-transfer function matrix where m and n are, respectively, the numbers of the input and output ports. The realization results in a grounded network requiring (2m+l)n EC one-ports and (m + l)n grounded operational amplifiers and hence is attractive from the practical point of view.     

无源二端口网络的综合

本文论述了双端接阻容负载RC二端口网络转移电压函数的极点与RC阻抗和导纳乘积的零,极点位置分布关系定理.导出了双端接载与等效单端接载网络转移电压函数之间关系的数学模型,利用一次归并和两次分解途径给出了双端接任意阻容负载网络的实现方法.     

ICI reduction scheme for OFDM system with phase noise over time‐varying channels

For mobile orthogonal frequency division multiplexing (OFDM) systems, time‐varying channels and random phase noise introduced by the oscillator result in severe intercarrier interference (ICI), respectively, and degrade the overall OFDM system performance. However, the existing ICI reduction methods only aim at a single interference source, i.e. either time‐varying channels or phase noise. Therefore, these methods are not suitable for the actual situation. In this paper, we analyze the spectral property of the transfer function composed of time‐varying channels and phase noise, and propose that the transfer function can be approximated by a finite parameter complex exponential basis expansion model (CE‐BEM). Then, a pilot‐aided minimum mean square error estimation is adopted to estimate the CE‐BEM coefficients in order to reconstruct the transfer function and reduce ICI. Finally, our simulation results show how the proposed scheme would improve the system performance in a time‐varying environment with phase noise. Copyright © 2008 John Wiley & Sons, Ltd.     

Highly stable RC active filters

The letter deals with an RC active filter of the feedback kind. The principle of the proposed circuit is based on Bangert's method. To compare this method with Yanagisawa's method, the same transfer function is used in the letter as is illustrated in Yanagisawa's paper.