Generation of CCII and ICCII based Wien oscillators using nodal admittance matrix expansion

This paper introduces a new generation method of the grounded capacitor Wien oscillator circuits using current conveyors (CCII) or inverting current conveyors (ICCII) or combination of both of them. The nodal admittance matrix (NAM) of the single Op Amp Wien oscillator is taken as the starting point in the new approach of systematic synthesis of equivalent oscillators. The synthesis procedure is based on the generalized systematic synthesis framework using NAM expansion. The resulting derived 32 oscillators include many novel oscillators, using current conveyors or inverting current conveyors or both. Comparison between the generated oscillators based on the effect of parasitic elements on the oscillator performance is discussed.     

NAM expansion method for systematic synthesis of OTA-based floating gyrators

This paper presents a NAM expansion method for systematically synthesizing OTA-based floating gyrators. After describing nullor-mirror components of OTAs, class I, II and III gyrators, which can be built with standard OTAs, are synthesized by using the nullor-mirror equivalent models described by NAM. The class-I gyrators employing two DO-OTAs have four equivalent realizations, the class-II gyrators employing three SO-OTAs have eight equivalent realizations, and the class-III gyrators employing four SISO-OTAs have 16 equivalent realizations. Having used canonic number of components, the circuits are easy to be integrated and their parameters can be tuned electronically through tuning bias currents of OTAs. Finally, as an example, the MULTISIM simulation results of a notch filter constructed by the OTA-based III gyrator are presented to verify the realizability of the derived circuits.     

Current conveyor based or unity gain cells based two integrator loop oscillators

Four alternative families of oscillators are considered in this paper, three of the families employ CCII or ICCII or combination of both and each family has sixteen oscillator circuit members. The fourth family uses unity gain cells and has four circuit members. Two alternative transformation methods are used in this paper for the generation of oscillators. The first one uses the adjoint circuit theorem to obtain a new family of current mode oscillators from a voltage mode oscillator circuit. The second transformation method uses the nodal admittance matrix (NAM) expansion to generate a grounded passive element oscillator family from an oscillator circuit, which employs a virtually grounded resistor. Although this paper has a tutorial nature it includes two new families of oscillators; one of them provides both current and voltage outputs and the other provides voltage outputs and is based on the use of voltage, current followers and inverters. Simulation results are included to support the analysis.     

Transformation of oscillators using Op Amps,unity gain cells and CFOA

A new approach in the systematic synthesis of current conveyor based active RC canonic oscillators is given. The synthesis procedure is based on the generalized systematic synthesis framework using admittance matrix expansion. The resulting derived oscillators include many novel oscillators, using various types of current conveyors and inverting current conveyors. The oscillators considered in this paper uses the minimum number of passive elements namely two capacitors and three resistors necessary to have independent control on the condition of oscillation and on the frequency of oscillation. The generated oscillators employ two grounded capacitors and have the advantage of their ability to absorb parasitic element effects. Three classes are considered in this paper, class I oscillators have a common node between one of the capacitors and one of the two grounded resistors. Class II oscillators have a common node between one of the capacitors and the floating resistor. Class III has all three resistors being grounded and one of them shares a node with one of the capacitors. It should be noted that this is the first paper in the literature to use nodal admittance matrix expansion in the generation of current conveyor oscillators. Spice simulation results are included to support the theory. The proposed method can be generalized to other active devices.     

Carrier Travel Time in Transistors

A recently reported two current feedback operational amplifier (CFOA)-based oscillator is converted to a family of 16 current mode oscillators using CCII or ICCII or combination of both. A transformation method based on nodal admittance matrix (NAM) expansion is used to transform the floating capacitor CFOA-based oscillator circuit to a family of 16 grounded capacitor oscillators using CCII or ICCII or combination of both. Two of the new grounded capacitor oscillator circuits have a floating property. Simulation results are included.     

On the generation of CCII and ICCII oscillators from three Op Amps oscillator

A new quadrature oscillator using two current conveyors (CCII) and two inverting current conveyors (ICCII) is generated from a three Op Amp two integrator loop oscillator. The proposed oscillator is generalized and it is found that it is a member of a family of 64 oscillator circuits using combination of CCII and ICCII. Four of the reported oscillators are floating. The three Op Amps oscillator is also found to be the reference oscillator circuit in the generation of two basic CCII two integrator loop grounded passive element oscillators. The nodal admittance matrix (NAM) expansion is used to show the basic steps in the generation of the two alternatives CCII grounded passive element oscillators. Each of the two CCII oscillators is a member of a family of sixteen oscillator circuits using combination of CCII and ICCII. Two of the reported oscillators are floating and their adjoint oscillator circuits are not floating. Simulation results are included.     

Systematic synthesis of CCCCTA-based T-T filters using NAM expansion method

In the light of nullor-mirror models for current-controlled current conveyor trans-conductance amplifier (CCCCTA), initiating the admittance matrices of the Tow-Thomas (T-T) filter, three different types of the T-T filter are synthesised by means of the nodal admittance matrix (NAM) expansion method. The type A filter, which employ one CCCCTA, one grounded resistor and two grounded capacitors, has eight different forms, the type B filter, which employ one CCCCTA, two grounded capacitors and a second-generation current-controlled conveyor (CCCII) or an second-generation inverting current-controlled conveyor (ICCCII) or an operational trans-conductance amplifier (OTA), has 64 different forms and the type C filter employing one CCCCTA and two grounded capacitors has eight different forms. In all, 80 voltage-mode/current-mode T-T filter circuits are obtained. Because of using canonic number components, the circuits are highly desirable from the viewpoint of IC fabrication and their parameters can be electronically tuned through tuning bias currents of CCCCTAs. The hand analysis and computer simulation results have been provided to support the synthesis method.     

Generalized model for Memristor-based Wien family oscillators

In this paper, we report the unconventional characteristics of Memristor in Wien oscillators. Generalized mathematical models are developed to analyze four members of the Wien family using Memristors. Sustained oscillation is reported for all types though oscillating resistance and time dependent poles are present. We have also proposed an analytical model to estimate the desired amplitude of oscillation before the oscillation starts. These Memristor-based oscillation results, presented for the first time, are in good agreement with simulation results.     

New minimum component electronically tunable OTA-C sinusoidal oscillators

Two new transconductance-amplifier-capacitor sinusoidal oscillators are introduced. Each circuit requires only two OTAs and two capacitors, the minimum number of components. The circuits can generate linearly tunable variable-frequency oscillations.<>     

Programmable Gm– C Filters Using Floating-Gate Operational Transconductance Amplifiers

We present programmable, fully differential G_m-C second-order sections (SOS) showing tunability over a wide range of frequencies. The SOSs use floating-gate operational transconductance amplifiers (FG-OTAs) to realize tunability. We present two FG programmable OTAs. The OTAs have a pFET input stage and employ current mirror topology. An FG common-mode feedback (CMFB) circuit as well as a conventional CMFB circuit is described for use with these OTAs. Their performance is compared. Expressions are derived for the differential and common-mode frequency response of the OTAs. Typical simulation and experimental results are shown for prototypes fabricated in a 0.5-mum CMOS process available through MOSIS. The prototypes operate from a single 3.3-V supply with typical bias currents in the 10-100-nA range. We present experimental results showing frequency-and Q-tuning for a low-pass SOS (LPSOS) and a bandpass SOS (BPSOS) designed using these FG-OTAs also fabricated in a 0.5-mum CMOS process. Measured 1-dB compression for LPSOS and BPSOS are -15 and -11 dBm, respectively     

Wien bridge oscillators using current conveyors

Realization of oscillators with single resistor control based on the circuit techniques of the second generation current conveyors (CC II) utilizing the separability of the Wien RC one-ports that are generalized through appropriate insertion of two more resistors is considered. The relative frequency stability is shown to improve over the conventional op-amp Wien bridge versions.     

Table-based linear transformation filters using OTA-C techniques

Linear transformation (LT) active filters using operational transconductance amplifiers (OTAs) and capacitors are presented. Based on the LT, two simple and systematic design tables are given to realise OTA-C filters efficiently. Using the proposed design tables, the synthesised all-pole and elliptic filters employ minimum numbers of OTAs and only grounded capacitors. As an example, a new third-order elliptic lowpass filter is realised. Experimental results are obtained to verify the theoretical analysis     

基于单个CCCCTA接地回转器的系统综合

为综合基于CCCCTA的接地回转器,根据CCCCTA的零-镜模型和接地回转器的节点导纳矩阵,利用节点导纳矩阵扩展法,我们实现了4个相互等效的接地回转器。导出的回转器具有两个特点,一个是通过调节CCCCTA的偏置电流,可以电控调节回转器的参数; 另一个特点是电路仅使用单个CCCCTA。作为一个例子,通过使用导出的回转器之一,我们实现了一个极点频率为1.274MHz、品质因素为4的带通滤波器。计算机仿真证明所导出的电路正确有效。     

Electronically tunable OTA-C mutually coupled circuit

A novel method for realising a mutually coupled circuit using operational transconductance amplifiers (OTAs) as active elements is proposed. The realised circuit is composed of eight OTAs and two grounded capacitors, and the values of a primary selfinductance, a secondary selfinductance and a mutual inductance can be independently tuned through the bias currents of the OTAs.<>     

Voltage-mode high-Q band-pass filters and oscillators employing single CDBA and minimum number of components

In this paper, voltage-mode second order high-Q band pass filters and oscillators which employ only single current differencing buffered amplifier (CDBA) as the active component are proposed. One of the four filter circuits and two of the four oscillators described have minimum passive component count properties, without using the internal pole of the active element. These BP filters can be easily cascaded without any recourse to impedance matching circuitry. The circuits have been analysed theoretically, simulated and experimentally tested in a laboratory. It is shown that the results of simulations and experimental work are in agreement with theoretical predictions.     

A New Multi-tanh-Based Non-linear Function Synthesiser

A new complementary metal-oxide-semiconductor transadmittance-mode with input voltage and output current, analogue non-linear odd-function synthesiser is presented. The proposed circuit is based on the assumption that a non-linear odd- function can be approximated by the summation of hyperbolic tangent (tanh) functions with different arguments. Each term of the tanh function expansion is realised by exploiting to advantage the inherent non-linearity of a current-controlled current-conveyor (CCCCII) (or an operational transconductance amplifier (OTA)) with a different bias current. The output currents of these CCCCIIs (OTAs) are weighted using the gains of current amplifiers. These weighted currents are algebraically added to form the required non-linear function. The proposed circuit is suitable for integration, can be easily extended to include higher order terms of the tanh-odd-function expansion and can be programmed to realise arbitrary hard non-linear odd-functions that cannot be easily realised using already existing techniques, based on the Taylor-series expansion, for synthesising non-linear functions. PSPICE simulation results, obtained from CCCCII-based realisations of selected hard non-linearities, demonstrating the functionality of the proposed circuit are included.     

Systematic Synthesis of Compressive VDTA-Based T-T Filter with Orthogonal Control of fo and Q

Based on sixteen nullor-mirror models of the voltage differencing transconductance amplifier (VDTA) and port admittance matrices of the tow-Thomas (T-T) filter with orthogonal control between the characteristic frequency (f_o) and figure of merit (Q), two different categories of the voltage-mode and transconductance-mode T-T filters are synthesized by the means of the nodal admittance matrix (NAM) expansion method. The category A filter that employs two compressive VDTAs and two grounded capacitors includes four structures, and the category B filter that uses two compressive VDTAs, two grounded capacitors, and one grounded resistor, also includes four structures. These circuits are suitable for integrated circuit manufacture, and their parameters f_o and Q can be orthogonally adjusted with varying the bias currents of VDTAs. After the paper and pencil test is completed, the computer analyses, including alternating current (AC), parameter sweep, Monte Carlo (MC), and noise analyses, are performed to support the synthesis approach.     

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.     

Electronically tunable versatile voltage-mode universal filter

A novel electronically tunable versatile voltage-mode universal biquad filter by using two single-output-operational transconductance amplifiers (OTAs), one differential difference current conveyor (DDCC) and two capacitors is proposed. The proposed circuit, which can be used as either a four-input single-output universal filter or a single-input three-output multifunction filter with the same topology. Besides, the new circuit offers the following advantageous features: realization of all the non-inverting and inverting biquadratic filter signals from the same configuration, no need to employ inverting-type input signals, no need to component-matching conditions and low passive sensitivity performance.     

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.