This paper describes a new electronically tunable three inputs and single output voltage-mode universal biquadratic filter based on simple CMOS operational transconductance amplifiers (OTAs) and grounded capacitors The proposed configuration provides lowpass, highpass, bandpass, bandstop and allpass voltage responses at a high impedance input terminal, which enable easy cascadability Additionally, the circuit parameters ω o and Q can be set orthogonally by adjusting the transconductances and grounded capacitors The filter also offers an independent electronic control of parameters ω o by adjusting the transconductance through the bias current/voltage of the OTA For realizing all the filter responses, no critical component matching condition is required, and all the incremental parameter sensitivities are low PSPICE simulation results are performed to confirm the theoretical analysis

Electronically tunable high-input impedance voltage-mode universal biquadratic filter based on simple CMOS OTAs

—In this paper a new second–order voltage– and current–mode universal biquadratic frequency filters using only single current conveyor transconductance amplifier (CCTA) and four passive elements are presented. The proposed voltage–mode universal filter has been transformed into current–mode universal filter using adjoint transformation method. Proposed circuits enables to realize the low–, band–, high–pass, band–stop and all–pass responses without changing the circuit topology and the possibility of independent control of the quality factor Q using single passive element. No component matching is required and all the passive and active sensitivities are low. PSPICE simulations and experimental results based on commercially available amplifiers OPA861 and MAX435 are included verify the theoretical conclusions of the proposed circuits.

/pdf/single-ccta-based-universal-biquadratic-filters-employing-4ry8ihaap4.pdf

Single CCTA–Based Universal Biquadratic Filters Employing Minimum Components

In this paper, a novel versatile active building block the differential-input buffered and transconductance amplifier (DBTA) is proposed. The application of the newly defined active function block is shown on the design of voltage-mode (VM), multi-input and single-output (MISO)-type multifunction biquad, employing single DBTA and five passive elements. Proposed VM filter structure can realize four filter functions i.e., low- (LP), band- (BP), high-pass (HP) and band-stop (BS) without changing the circuit topology and enables independent control of the quality factor Q using single passive element. Theoretical results are verified by PSPICE simulations using a BJT realization of DBTA.

https://www.jstage.jst.go.jp/article/elex/6/6/6_6_329/_pdf

The conception of differential-input buffered and transconductance amplifier (DBTA) and its application

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 configuratio...

/pdf/new-voltage-mode-universal-filter-and-sinusoidal-oscillator-35aolymacb.pdf

New voltage-mode universal filter and sinusoidal oscillator using only single DBTA

This paper presents an independently tunable five-input and three-output voltage-mode biquadratic filter using five single-ended output operational transconductance amplifiers (OTAs) and two grounded capacitors. The proposed circuit can be connected to the input terminals in different ways to form a lowpass, bandpass, highpass, bandreject and allpass filter. Unlike the previously reported works, the proposed circuit can realize both non-inverting/inverting lowpass, bandpass, and bandreject filtering responses. The proposed circuit not only allows for the orthogonal controllability of the resonance angular frequency (ωo) and quality factor (Q), but also achieves independent controllability of the parameters ωo and ωo/Q without the need for control factor matching conditions. The new circuit has the following advantages: single-input three-output biquadratic filter or five-input single-output biquadratic filter with single topology, electronic tunable of parameters ωo, Q, and ωo/Q, high input impedance, resistorless structure, and no need for inverted input signals. Moreover, as an application, a quadrature sinusoidal oscillator with fully-uncoupled electronically controllable both frequency of oscillation and condition of oscillation is designed using the proposed filter. The workability of the proposed circuits is validated by OrCAD PSpice simulation program and experimental results. The given results are consistent with theoretical expectations.

Independently tunable voltage-mode OTA-C biquadratic filter with five inputs and three outputs and its fully-uncoupled quadrature sinusoidal oscillator application

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.

Jenn-Pyng Wang

Papers

Electronically tunable versatile voltage-mode universal filter