Current-Mode First-Order Allpass Filter Employing Single Current Operational Amplifier

A current-mode first-order allpass filter configuration is proposed. The presented circuit uses a single current operational amplifier (COA), a resistor and a capacitor, which are of minimum number. High output impedance of the proposed filter enables the circuit to be cascaded without additional buffers. The proposed circuit is insensitive to parasitic input capacitances and input resistances due to internally grounded input terminals of COA. It does not impose any component matching constraint in analog signal processing circuits. Non-ideal effects of COA to the first-order allpass network are also investigated. To demonstrate the performance of the proposed filter a new current-mode quadrature oscillator is given as an application example. The theoretical results are verified with PSPICE simulations using a new realization of fully differential CMOS COA.     

Resistorless realization of current-mode first-order allpass filter using current differencing transconductance amplifiers

This paper presents a realization of a current-mode first-order allpass filter using two current differencing transconductance amplifiers (CDTAs) as the active components and one virtually grounded capacitor as the only passive component. The proposed filer requires no external resistor and is electronically adjustable by varying the external bias current of the CDTA. No component-matching constraints are required. The circuit realizes both inverting and non-inverting types of allpass filters, and also exhibits high-output impedances, which are easy cascading in the current-mode operation. As an application of the proposed CDTA-based allpass section, a current-mode quadrature oscillator is realized. PSPICE simulation results are given to confirm the theoretical analysis.     

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.     

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.     

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.     

MOS-C single amplifier biquads using the operational transresistance amplifier

A configuration for the realization of voltage-mode second-order filters employing a single operational transresistance amplifier (OTRA) as the active element is presented. This topology can synthesize lowpass, highpass, bandpass, notch and allpass filtering functions. The presented filters are suitable for MOS-C implementation, yielding the filter parameters to be electronically tunable. Theoretical analysis is verified with PSPICE simulation.     

First-order allpass filter and sinusoidal oscillators using DDCCs

A voltage-mode first-order allpass filter using one differential difference current conveyor (DDCC), one grounded capacitor and one floating resistor is presented. No passive component matching constraints are required. Because the output impedance of the proposed allpass filter is low, the output terminal can be directly connected to the next stage. Using the proposed first-order allpass filter as a basic building block, a new quadrature oscillator and even-phase sinusoidal oscillators can be obtained. The simulation results confirm the theoretical analysis.     

Cascadable Current-Mode Biquad Filter and Quadrature Oscillator Using DO-CCCIIs and OTA

This article introduces a circuit which can function both as a quadrature oscillator and as a universal biquad filter (lowpass, highpass, bandpass). When the circuit functions as a universal biquad filter, the quality factor and pole frequency can be tuned orthogonally via the input bias currents. When it functions as a quadrature oscillator, the oscillation condition and oscillation frequency can be adjusted independently by the input bias currents. The proposed circuit can work as either a quadrature oscillator or a biquad filter without changing the circuit topology. The amplitude of the proposed oscillator can be independently controlled via the input bias currents. The proposed oscillator can be applied to provide amplitude modulated/amplitude shift keyed signals with the above-mentioned major advantages. The circuit is very simple, consisting of four dual-output second generation current controlled current conveyors (DO-CCCIIs), one operational transconductance amplifier (OTA), and two grounded capacitors. Without any external resistors and using only grounded elements, this circuit is therefore suitable for IC architecture. PSPICE simulation results are depicted here, and the given results agree well with the theoretical analysis. The power consumption is approximately 7.32 mW at ±2.5 V supply voltages.     

A systematic realization of third-order quadrature oscillator with controllable amplitude

A systematic realization of third-order quadrature oscillator using a voltage-mode non-inverting lowpass filter and a voltage-mode inverting lossless feedback integrator is presented in this paper. The proposed circuit consists of two multiple-output differential voltage current conveyor transconductance amplifiers (MO-DVCCTAs), two grounded resistors and three grounded capacitors. The new circuit provides three quadrature voltage outputs, two high-impedance quadrature current outputs, and one high-impedance current output with controllable amplitude, simultaneously. When the input bias current of the first MO-DVCCTA is a modulating signal, the circuit can generate amplitude modulation or amplitude shift keying signals. The condition of oscillation and the frequency of oscillation can be controlled independently through grounded resistors. The proposed circuit only uses grounded capacitors and grounded resistors, which can be easily implemented as an integrated circuit. The experimental results and H-Spice simulation results are given to confirm the theoretical analysis.     

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.     

Resistorless dual-mode quadrature sinusoidal oscillator using a single active building block

This paper presents a new realization of resistorless mixed-mode (i.e. both voltage-mode and current-mode) quadrature sinusoidal oscillator using a new active building block (ABB) called the differential voltage current-controlled conveyor transconductance amplifier (DVCCCTA). The proposed oscillator circuit uses a single DVCCCTA, two grounded capacitors (GCs) and does not employ any external linear resistors. The tuning laws for the condition of oscillation (CO) and the frequency of oscillation (FO) are non-interactive; and controlled by separate bias currents. The circuit provides two explicit quadrature current outputs and two quadrature voltage outputs and thus can be classified as a mixed-mode quadrature oscillator. Another notable feature of the proposed circuit is that it can also be used as a biquadratic filter to realize low-pass and band-pass filtering functions simultaneously. Non-ideal analysis of the circuit is provided and PSpice simulation results have been included to verify the workability of the proposed circuit.     

OTRA-based Grounded-FDNR and Grounded-Inductance Simulators and Their Applications

New grounded frequency-dependent negative-resistance (FDNR) and grounded inductance simulation circuits, employing an operational trans-resistance amplifier (OTRA) along with two capacitors, two resistors and a voltage follower have been introduced. The application of the new simulators in the realization of a single-resistance controlled oscillator (SRCO) and a single-capacitance controlled oscillator (SCCO) has been demonstrated and the effect of parasitic capacitance and input and output resistances of the OTRA on the performance of these circuits has been evaluated. The workability of the application circuits has been confirmed by experimental results using an OTRA-implemented from commercially available AD844-type current-feedback operational amplifiers (CFOAs).     

Quadrature oscillator and universal filter based on translinear current conveyors

This paper presents quadrature oscillator and universal filter based on translinear current conveyors. The proposed circuit can realize as a quadrature oscillator or a universal filter without changing the circuit topology. When it works as a quadrature oscillator, four quadrature current outputs and two quadrature voltage outputs can be obtained. The condition and frequency of oscillation of oscillator can be controlled orthogonally and electronically. When it works as a universal filter, low-pass, band-pass, high-stop, band-stop, and all-pass filtering functions can be obtained simultaneously. The natural frequency and quality factor of filters can be controlled orthogonally and electronically. The proposed topology is simulated using PSPICE simulators and experimental results are also used to confirm workability of new circuit.     

An integrable gm-C quadrature oscillator

An integrable quadrature oscillator circuit is given which uses only transconductance elements and grounded capacitors in its realization. The circuit provides four quadrature outputs of equal magnitude. It uses a low component count and is compatible for monolithic implementation in MOS technology. The simulation results on the quadrature oscillator verify the theory.     

基于OTRA的通用双二阶滤波器设计

提出了把通用双二阶滤波器视为负反馈放大器的观点,根据反馈电路的基本方程,利用3个MOS电阻、2个电容、2个运算跨阻放大器(OTRA)构成了通用双二阶滤波器,该滤波器不仅可从同一端口输出信号,从不同端口输入信号,而且可获得低通、高通、带通、带阻和全通输出.该电路结构简单,便于电控调谐.     

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.     

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。     

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.     

Novel voltage/current-mode quadrature oscillator using current differencing transconductance amplifier

This letter proposes a new realization of voltage/current-mode (CM) quadrature oscillator (QO) using Current Differencing Transconductance Amplifier (CDTA) as the active element. The proposed circuit employs canonic number of components, namely two CDTAs, one resistor and two grounded capacitors. The oscillator is capable of providing two explicit quadrature current outputs and two quadrature voltage outputs. Moreover, the circuit enjoys the advantage of independent control of condition of oscillation (CO) and frequency of oscillation (FO). The non-ideal analysis and sensitivity study of the circuit has been carried out and the circuit exhibits a good sensitivity performance. B2SPICE simulation results are included that validate the working of the circuit.