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This paper presents a novel voltage-controlled current-mode second-order multifunction frequency filter employing CFTAs (Current Follower Transconductance Amplifier) and PCAs (Programmable Current Amplifier). Possible internal bipolar structure of the CFI'A+/- element and the realization of the PCA using current multiplier EL2082 and secondgeneration current conveyor CCII+/- are presented. The proposed filter structure enables realizing the low- (LP), band- (BP), high-pass (HP) and the band-stop (BS) responses. The properties of the proposed filter were verified using PSPICE simulations. [ABSTRACT FROM AUTHOR]

In this paper a new active element for the realization of current-mode analog blocks Current Follower Transconductance Amplifier (CFTA) is presented. The element is a combination of the Current Follower (CF) and the Balanced Output Transconductance Amplifier (BOTA). In the paper we also document another extended active element CFTA which has more current outputs than can be realized by the UCC-N1B circuit, which was developed at our workplace. The application of this active element is shown on the realization of current-mode second-order universal frequency filters of the type SIMO (single-input-multi-output) and MISO (multi-input-single-output). The circuit structure consists of three active and three passive elements. The circuit was analyzed using signal-flow graphs. The properties of the proposed universal filter were subjected to a sensitivity analysis and AC analysis using PSpice software. [ABSTRACT FROM AUTHOR]

In this paper a new topology of current-mode multifunction frequency filters employing a single Multi-Output Current Amplifier (MOCA) is shown. The general method of filter design using an MOCA amplifier, when the initial design starts from a simple autonomous circuit, is shown. The design of internal transistor structure of the MOCA, which comes out from the internal structure of the second-generation current-conveyor (CCII+/-), is presented. It is used for the implementation of the proposed multifunction filter. The properties of the proposed second-order multifunction filter were subjected to a theoretical analysis using signal-flow graphs and AC analysis using the PSPICE software. [ABSTRACT FROM AUTHOR]

In this article, a new voltage-mode second-order universal frequency filter and sinusoidal oscillator using only single differential-input buffered and transconductance amplifier (DBTA) is presented. The proposed voltage-mode filter structure using single DBTA and four passive elements can provide all standard filter functions, i.e. low-, band-, high-pass, band-stop, and all-pass without changing the circuit topology and enables independent control of the quality factor Q using single passive element. The circuit requires the minimal number of active and passive elements with no conditions for component matching. By slight modification of the proposed filter structure, the new DBTA-based sinusoidal oscillator is easily obtained. The oscillation condition and the oscillation frequency are independently adjustable by different virtually grounded passive elements. The proposed sinusoidal oscillator employs only grounded capacitors. The passive and active sensitivities of all the proposed circuit configurations are low. PSPICE simulations using a BJT realisation of DBTA and experimental results based on commercially available amplifiers OPA860 and MAX436 are included, which prove the workability of the proposed circuits. [ABSTRACT FROM AUTHOR]