Electronically tunable multiple-input single-output voltage-mode multifunction filter employing simple CMOS OTAs

Abstract

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

Electronically tunable voltage-mode universal filter using simple OTAs

“…However, these filters can not benefit from orthogonal control of the natural frequency (Z o ) and quality factor (Q). Recently, simple CMOS OTA-based voltage-mode universal biquad filters have been developed with either a single-input multipleoutput or a multiple-input single-output [8]- [12]. However, these filters still can not benefit from orthogonal control of the parameters Z o and Q.…”

“…Several voltage-mode biquadratic filters based on OTAs have been reported, e.g. [2]- [12]. In [2], a two integrator loop universal biquad filter using eight OTAs and two grounded capacitors is proposed.…”

Voltage-mode three inputs five outputs universal biquad employing OTAs

“…From the point of ease of the filter implementations, it is prefer to realize the active filters by using only a kind of active components. A universal filter employs OTAs have been proposed in [21]. However, it can not benefit from orthogonal control of the natural frequency (ω o ) and the quality factor (Q).…”

“…Beside, the active filters employing grounded capacitors are beneficial from the point of view of integrated circuit (IC) implementation [2]. At the last three decades, many OTA based universal biquad filters have been reported [3]- [21]. Considering the number of input and output terminals, these filters can be classified into three categories: (i) a single-input, multiple-output (SIMO) type [3]- [7], (ii) a multiple-input, single-output (MISO) type [8]- [13] and (iii) a multiple-input, multiple-output (MIMO) type [14]- [21].…”

“…At the last three decades, many OTA based universal biquad filters have been reported [3]- [21]. Considering the number of input and output terminals, these filters can be classified into three categories: (i) a single-input, multiple-output (SIMO) type [3]- [7], (ii) a multiple-input, single-output (MISO) type [8]- [13] and (iii) a multiple-input, multiple-output (MIMO) type [14]- [21]. Generally, the SIMO filters can simultaneously realize three basic filter functions, i.e., LP, BP and HP, at a time without altering the connection way of the circuits and without input signal matching.…”