Uğur Çam

Current-Mode High Output Impedance Sinusoidal Oscillator Configuration Employing Single FTFN

In this study, a general current-mode high output impedance sinusoidal oscillator configuration is proposed. The proposed oscillator configuration uses a single four terminal floating nullor (FTFN), two capacitors and five resistors. The oscillator configuration exhibits high output impedance which makes easy to drive loads without using any buffering devices and provide non-interactive control of oscillation condition and oscillation frequency. The proposed topology also yields single frequency oscillators with reduced number of passive components. All of the proposed oscillators permit good frequency stability and exhibit low active and passive sensitivities. Theoretical analysis is verified with experimental results.

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.

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 Lossless Floating Immittance Simulator Employing Only Two FTFNs

In this paper a novel lossless floating immittance simulator employing only two FTFNs is reported. The presented topology enables the simulation of ideal floating inductance, FDNR and resistively variable capacitor. No component matching constraints are imposed for the realisations. The performance of the proposed floating immittance is demonstrated on a fifth order elliptic filter.

New Voltage and Current Mode First-order All-pass Filters Using Single FTFN

In this study, a voltage-mode and a current-mode first-order all-pass filter are presented. The voltage-mode allpass filter contains a single FTFN, a capacitor and two grounded resistors. The all-pass filter uses less passive elements than the other all-pass filters in the literature. The current-mode filter also uses a single FTFN, a capacitor and three resistors. The output of the current-mode all-pass filter exhibits high output impedance so that this property makes the circuit very attractive from the viewpoint of cascadability. The tracking error performance for the proposed filters is also examined. The theoretical results are verified by PSPICE simulations. Übersicht In dieser Arbeit werden jeweils ein Allpaßfilter erster Ordnung vom Spannungstyp bzw vom Stromtyp vorgestellt. Ersteres enthält neben einem FTFN einen Kondensator und zwei einseitig geerdete Widerstände und somit weniger passive Elemente als aus der Literatur bekannt Das Filter vom Stromtyp verwendet neben dem einen FTFN einen Kondensator und drei Widerstände. Sein Ausgang hat eine hohe Ausgangsimpedanz, eine Eigenschaft, die diesen Schaltkreis für kaskadierte Funktionen interessant werden läßt. Eine Untersuchung der Gleichlauffehler wird vorgenommen. Die theoretischen Ergebnisse werden mit PSPICE-Simulationen bestätigt. Für die Dokumentation FTFN / Allpaßfilter / Schaltkreise vom Stromund Spannungstyp Frequenz 54(2000) 7-8 l. Introduction 2. The proposed circuits First-order all-pass filters are widely used for phase shifting while keeping the amplitude of input signal constant over the frequency range of interest The all-pass filters can be also utilised for synthesis of multiphase oscillators and second-order band-pass filters 11 ]. Op-amp and CCII-based first-order all-pass filters are available in the literature [1-3]. However the four terminal floating nullor (FTFN) has been also receiving considerable attention recently, since it has been shown that an FTFN is a very flexible and versatile building block in active network synthesis [4-14]. The FTFN contains both floating voltage follower and current follower without having any common node which makes easy synthesis of current and voltage-mode analogue signal processing circuits. In [1] a voltage mode all-pass filter has been presented which contains an op-amp, three resistors and a capacitor. A set of CCII+ based allpass filters have been presented in the literature [3]. The circuits use more than one floating elements which is not suitable 1C integration principles. On the contrary a few current-mode first order all-pass filters have been proposed up to now [5]. The filter employs a single FTFN, a capacitor and two resistors. The main disadvantage of this circuit is that it can not provide high impedance current output. An additional current buffer is needed to sense the output current. In this study a voltage-mode and a current-mode first-order all-pass filters are presented. The voltage-mode all-pass filter contains a single FTFN, a capacitor and two grounded resistors. It uses less passive elements than the other filters in the literature [ 1-3]. The current-mode filter also uses a single FTFN, a ca-, pacitor and three resistors. The output of the current-mode filter exhibits high output impedance so that this property makes the circuit very attractive from the viewpoint of cascadability. Both voltage and current mode all-pass filters can also use the CCIIinstead of the FTFN, since the FTFN is a more general active building block compared to a current conveyor and an operational amplifier. Tracking error analyses for the proposed filters are also performed. 1 Sakarya University, Esentepe, Adapazan, Turkey 2 BogaziQi University, Bebek, Istanbul, Turkey 3 Istanbul Technical University, Maslak, Istanbul, Turkey A FTFN is equivalent to an ideal nullor or is called operational floating amplifier [4-14]. The FTFN shown in Fig. 1 is characteris-ed by the following port relations:

Cascadable Voltage-Mode Multifunction Biquad Employing Single OTRA

Abstract – A voltage-mode (VM), multi-input single-output (MISO) type multifunction biquad is proposed. It uses only one operational transresistance amplifier (OTRA) as the active element, while previously reported VM multifunction filters require more OTRAs. Proposed MISO type biquad configuration can realize all five different filter transfer functions. Theoretical results are verified with PSPICE simulations using a CMOS realization of OTRA.

On the realization of OTA-C oscillators

In this study, six tunable sinusoidal oscillator topologies, two of them known from the literature, are proposed using only CMOS operational transconductance amplifiers (OTAs) and grounded capacitors. The oscillator configurations have the properties of oscillation frequency control using the transconductance gain without affecting the oscillation condition, the suitability for very large scale integration (VLSI) since they are composed of only OTAs and grounded capacitors, and the capability of operation at high frequency. For the proposed topologies, the non-ideality effects of an OTA such as finite output conductance, and finite bandwidth are investigated, and for one of the proposed OTA-C oscillator circuits the maximum output signal level is determined using a simple formula that does not cause clipping and the slew-rate-limiting problem. The theoretical results are verified by SPICE simulation results. The oscillator topologies are simulated with the SPICE computer program and the resulting output v...

Cascadable allpass and notch filters employing single operational transresistance amplifier

A new voltage-mode filter configuration is proposed. The presented topology uses single operational transresistance amplifier (OTRA) and can realize first-order allpass, second-order allpass and notch filtering functions. The proposed circuits are insensitive to parasitic capacitances and resistances due to internally grounded input terminals of OTRA. Low output impedance of the configuration enables the circuits to be cascaded without additional buffers. The theoretical results are verified with PSPICE simulations using a CMOS realization of OTRA. Experimental work is also carried out. The feasibility of the proposed first-order allpass filter is illustrated on the design of a quadrature oscillator.

Catalogue of Variable Frequency and Single-Resistance-Controlled Oscillators Employing A Single Differential Difference Complementary Current Conveyor

A set of fourteen current-mode sinusoidal oscillators employing a single differential difference complementary current conveyor (DDCCC) is proposed. This is the largest catalogue of sinusoidal oscillators with single resistor frequency control, that use only a single active building block (ABB) and minimum number of passive components. The proposed topologies were automatically designed by a genetic algorithm rather than by a human designer. Some of the synthesized networks have very attractive topological features. PSPICE simulation results and non-ideal analysis of the oscillators has been included. Index Terms – sinusoidal oscillators, current conveyors, genetic algorithms

A new CMOS realization of a four terminal floating nullor (FTFN)

A novel circuit configuration for the realization of a four terminal floating nullor in CMOS technology is proposed. The circuit proposed combines the advantages of a cascade of common-source and common-gate amplifiers and a floating current source. PSPICE simulations show that the proposed circuit is suitable for wideband, accurate and wide dynamic range current-mode signal processing. The feasibility of the circuit is also tested successfully in a current-mode band-pass filter structure.