New Universal Current-mode Biquad Using Only Three ZC-CFTAs

The objective of this paper is to present a new universal Current-mode biquad capable of providing all the five basic filter functions, namely, low pass (LP), Band pass (BP), high pass (HP), Band reject (BR) and all pass (AP) from the same configuration using only three Z - copy current follower transconductance amplifiers (ZC-CFTA) along with the provision of independent electronic tunability of the filter parameters f0 and Q0 (or bandwidth) through two separate DC bias currents while employing both grounded capacitors as desirable for integrated circuit implementation. The workability of the proposed structure is verified by PSPICE simulations based on CMOS implementation of the ZC-CFTA

Single-Input Five-Output Electronically Tunable Current-Mode Biquad Consisting of Only ZC-CFTAs and Grounded Capacitors

This paper presents an electronically tunable current-mode biquadratic filter constructing with four Z-copy current follower transconductance amplifiers (ZC-CFTAs) and only two grounded capacitors. The presented filter can realize all the five standard biquadratic functions simultaneously without requiring any component matching conditions and connecting any relevant output currents. The circuit has one low-impedance input and five high-impedance outputs, resulting in easy cascadability in current-mode. Also, the developed circuit exhibits the advantage of non-interactive electronic control of the natural angular frequency and the quality factor Q along with low incremental active and passive sensitivities. Computer simulation results using PSPICE program are given to confirm the validity of the theoretical prediction and to point out the attractive performance of the circuit

SFG Synthesis of General High-Order All-Pass and All-Pole Current Transfer Functions Using CFTAs

An approach of using the signal flow graph (SFG) technique to synthesize general high-order all-pass and all-pole current transfer functions with current follower transconductance amplifiers (CFTAs) and grounded capacitors has been presented. For general nth-order systems, the realized all-pass structure contains at most n + 1 CFTAs and n grounded capacitors, while the all-pole lowpass circuit requires only n CFTAs and n grounded capacitors. The resulting circuits obtained from the synthesis procedure are resistor-less structures and especially suitable for integration. They also exhibit low-input and high-output impedances and also convenient electronic controllability through the -value of the CFTA. Simulation results using real transistor model parameters ALA400 are also included to confirm the theory

Novel active function blocks and their applications in frequency filters and quadrature oscillators

Kmitočtové filtry a sinusoidní oscilátory jsou lineární elektronické obvody, které jsou používány v široké oblasti elektroniky a jsou základními stavebními bloky v analogovém zpracování signálu. V poslední dekádě pro tento účel bylo prezentováno velké množství stavebních funkčních bloků. V letech 2000 a 2006 na Ústavu telekomunikací, VUT v Brně byly definovány univerzální proudový konvejor (UCC) a univerzální napět'ový konvejor (UVC) a vyrobeny ve spolupráci s firmou AMI Semiconductor Czech, Ltd. Ovšem, stále existuje požadavek na vývoj nových aktivních prvků, které nabízejí nové výhody. Hlavní přínos práce proto spočívá v definici dalších původních aktivních stavebních bloků jako jsou differential-input buffered and transconductance amplifier (DBTA), current follower transconductance amplifier (CFTA), z-copy current-controlled current inverting transconductance amplifier (ZC-CCCITA), generalized current follower differential input transconductance amplifier (GCFDITA), voltage gain-controlled modified current-feedback operational amplifier (VGC-MCFOA), a minus-type current-controlled third-generation voltage conveyor (CC-VCIII-). Pomocí navržených aktivních stavebních bloků byly prezentovány původní zapojení fázovacích článků prvního řádu, univerzální filtry druhého řádu, ekvivalenty obvodu typu KHN, inverzní filtry, aktivní simulátory uzemněného induktoru a kvadraturní sinusoidní oscilátory pracující v proudovém, napět'ovém a smíšeném módu. Chování navržených obvodů byla ověřena simulací v prostředí SPICE a ve vybraných případech experimentálním měřením.Frequency filters and sinusoidal oscillators are linear electric circuits that are used in wide area of electronics and also are the basic building blocks in analogue signal processing. In the last decade, huge number of active building blocks (ABBs) were presented for this purpose. In 2000 and 2006, the universal current conveyor (UCC) and the universal voltage conveyor (UVC), respectively, were designed at the Department of Telecommunication, BUT, Brno, and produced in cooperation with AMI Semiconductor Czech, Ltd. There is still the need to develop new active elements that offer new advantages. The main contribution of this thesis is, therefore, the definition of other novel ABBs such as the differential-input buffered and transconductance amplifier (DBTA), the current follower transconductance amplifier (CFTA), the z-copy current-controlled current inverting transconductance amplifier (ZC-CCCITA), the generalized current follower differential input transconductance amplifier (GCFDITA), the voltage gain-controlled modified current-feedback operational amplifier (VGC-MCFOA), and the minus-type current-controlled third-generation voltage conveyor (CC-VCIII-). Using the proposed ABBs, novel structures of first-order all-pass filters, second-order universal filters, KHN-equivalent circuits, inverse filters, active grounded inductance simulators, and quadrature sinusoidal oscillators working in the current-, voltage-, or mixed-mode are presented. The behavior of the proposed circuits has been verified by SPICE simulations and in selected cases also by experimental measurements.

Mixed-Mode Third-Order Quadrature Oscillator Based on Single MCCFTA

This paper presents a new mixed-mode third-order quadrature oscillator based on new modified current-controlled current follower transconductance amplifier (MCCFTA). The proposed circuit employs one MCCFTA as active element and three grounded capacitors as passive component which is highly suitable for integrated circuit implementation. The condition and frequency of oscillations can be controlled orthogonally and electronically by adjusting the bias currents of the active device. The circuit provides four quadrature current outputs and two quadrature voltage outputs into one single topology, which can be classified as mixed-mode oscillator. In addition, four quadrature current output terminals possess high-impedance level which can be directly connected to next stage without additional buffer circuits. The performance of the proposed structure has been verified through PSPICE simulators using 0.25 µm CMOS process from TSMC and experimental results are also investigated