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A novel high speed linear tunable transconductor suitable for analog and mixed-signal fuzzy circuits operating in current mode is proposed. Using this OTA, we construct a high speed fuzzifier and implement trapezoidal/triangular functions with all parameters (slope, width, and position) independently and continuously tunable, and excellent for low voltage applications. Computer simulations verify the performance of this circuit, showing high speed (up to 100 MHz) and a high support range (up to 2.5 V).

In this paper, a universal current-mode second-order active-C filter for simultaneously realizing low-pass, band-pass and high-pass responses is proposed. The presented filter employs only three plus-type second-generation current-controlled conveyors (CCCII+s). This filter needs no critical active and passive component matching conditions and no additional active and passive elements for realizing high output impedance low-pass, band-pass and high-pass characteristics. The angular resonance frequency (ω₀) and quality factor (Q) of the proposed resistorless filter can be tuned electronically. To verify the theoretical analysis and to exhibit the performance of the proposed filter, it is simulated with SPICE program.

In this paper, a new current-mode (CM) all-pass filter employing two Dual-Output Second-Generation Current Conveyors (DO–CCIIs), one grounded resistor and one grounded capacitor is presented. The proposed circuit exhibits low input impedance and high output impedance, which makes it suitable for cascading. Moreover, adding two extra resistors to the proposed circuit, a new gain-variable voltage-mode (VM) all-pass filter is obtained. A quadrature oscillator employing minimum number of grounded passive components is derived from the developed CM filter as an application of the first-order all-pass filter. Both of the proposed all-pass filters do not require matching of passive components. The effects of the parasitic impedances of the DO–CCIIs on the transfer function (TF) of the proposed CM filter as an example are investigated. In addition, the proposed CM all-pass filter and oscillator circuit are simulated using SPICE simulation program to confirm the theory.

In this paper, an electronically tunable current-mode (CM) universal biquad filter is proposed. The proposed filter employs three dual-X second-generation current conveyors (DXCCIIs), two grounded capacitors and four NMOS transistors acting as resistors. The proposed filter simultaneously realizes standard filter functions such as low-pass (LP), band-pass (BP), and high-pass (HP) responses. The notch (NH) and all-pass (AP) functions can also be obtained by connecting appropriate output currents directly without using additional active elements. The output signals are obtained at high output impedance terminals, which is important for easy cascading in CM operation. SPICE simulation results are given to verify the theoretical analyses.

In this paper, four instrumentation amplifier (IA) topologies, one of which is current-mode (CM) while the others are voltage-mode (VM), are presented. Three of the IAs use one to two current feedback operational amplifiers (CFOAs) while the other one employs only a single NMOS transistor. One of the IA circuits, given as an example, is simple while others are novel. The CM IA is composed of only grounded resistors which have some advantages in integrated circuit (IC) process. Non-ideality effects such as non-ideal gain and parasitic impedances on the performance of introduced IAs are discussed. In order to show the performance of the circuits, we perform experimental tests and simulations by using SPICE program.

In this paper, a CMOS-based one input-two output current-mode (CM) circuit structure for providing full-wave rectification and half-wave rectifications to clarify the theory is proposed. The suggested configuration has many important advantages such as dissipating very less power, employing reduced number of CMOS transistors, having high output impedance currents and without requiring any additional bias currents and voltages. In order to exhibit performance and effectiveness of the proposed topology, SPICE simulation results are given.

In this paper, a new current-mode (CM) circuit for realizing all of the first-order filter responses is suggested. The proposed configuration contains low number of components, only two NMOS transistors both operating in saturation region, two capacitors and two resistors. Major advantages of the presented circuit are low voltage, low noise and high linearity. The proposed filter circuit can simultaneously provide both inverting and non-inverting first-order low-pass, high-pass and all-pass filter responses. Computer simulation results achieved through SPICE tool and experimental results are given as examples to demonstrate performance and effectiveness of the proposed topology.

A current-mode universal biquadratic filter with three input terminals and one output terminal is presented. The architecture uses two current conveyors (CCs), two grounded capacitors and two grounded resistors; and can realize all standard second-order filter functions — highpass, bandpass, lowpass, notch and allpass. Moreover, the circuit still offers the following advantage features: very low active and passive sensitivities, using of grounded capacitors and resistors which is ideal for integrated circuit implementation, without requirements for critical component matching conditions and very high output impedance. The workability of the proposed circuit has been verified via HSPICE simulations using TSMC 0.18 μm, level 49 MOSFET technology.

In this paper, a novel first-order current-mode (CM) electronically tunable all-pass filter including one grounded capacitor and two dual-output current followers (DO-CFs) is presented. The used DO-CFs are implemented using only 10 MOS transistors granting the proposed CM all-pass filter extremely simple structure. The proposed filter is suitable for integrated circuit (IC) fabrication because it employs only a grounded capacitor and is free from passive component matching conditions. Interestingly the introduced configuration uses minimum number of components compared to other works. It also offers other interesting advantages such as, alleviating all disadvantages associated with the use of resistors, easy cascadability and satisfies all technology requirements such as small sizing, simple realization, low voltage and low power operation. Additionally, the circuit parameters can be easily set by adjusting control voltages. Most favorably, the proposed CM all-pass filter can be simply used as a voltage-mode (VM) all-pass filter with outstanding properties of adjustable gain and tunability. To further show the versatility of the proposed structure a sinusoidal oscillator is also derived from presented CM all-pass filter. Nonideal gain and parasitic impedance effects on developed CM filter are discussed. Finally, simulation results with SPICE program are included to confirm the theory.

This paper presents three current-mode quadrature oscillator (QO) circuits based on dual-output current differencing transconductance amplifier (DO-CDTA) which is designed from block diagram. The proposed circuits consist of two DO-CDTAs and two grounded capacitors. The circuits can provide two sinusoidal output currents with 90° phase difference. The condition of oscillation (CO) can be adjusted independently from the frequency of oscillation (FO) by adjusting the bias currents of the DO-CDTA. The proposed circuits have high output impedance appropriate for cascade connection application in current mode which is capable to directly drive load. The circuits use only grounded capacitors without any external resistor which is very appropriate for further development into an integrated circuit. Moreover, the oscillator circuits can also adjust amplitude of the output signal. The results of PSPICE simulation program are corresponding to the theoretical analysis.

In this paper, the simplest possible electronically adjustable transresistance-mode (TRM) instrumentation amplifier (IA) using only eight MOS transistors is presented. Extremely simple structure of the proposed IA leads to a wide bandwidth and robust performance against mismatches and parasitic capacitances. Of more interest is that the differential-mode gain of the proposed IA can be electronically varied by control voltages. Post-layout and pre-layout simulation results based on 0.18$\mu$m TSMC CMOS parameters are included to confirm the validity of the theoretical analysis. Despite extremely simple structure, its input and output impedances are 1.93 and 1.68k$\mathrm{\Omega }$, respectively. Time domain analysis shows that for an input signal of 20$\mu$A peak to peak, maximum value of THD is 4.5% for different frequencies. Monte Carlo simulation is also carried out, which proves robust performance of the proposed IA against mismatches. The required chip area is only $17.1\times 36.9\mu {\mathrm{\text{m}}}^2$.

In this paper, a new first-order current-mode (CM) universal filter employing two dual output second-generation current conveyors (DO-CCIIs), one resistor and a grounded capacitor is proposed. The proposed filter has low input and high output impedances; thus, it can be easily connected with other CM circuits. It can simultaneously realize first-order low-pass (LP) and all-pass (AP) responses and can provide high-pass (HP) response with interconnection of LP and AP responses. It can be tuned electronically by replacing with dual output second-generation current controlled conveyors (DO-CCCIIs) instead of DO-CCIIs and removing the resistor. It has only a resistor but no capacitor connected in series to X terminal of DO-CCII; accordingly, it can be operated at high frequencies. Also, it does not need any critical passive component matching conditions and cancellation constraints. A number of simulation results based on SPICE program are included to exhibit performance, workability and effectiveness of the proposed filter configuration.

This paper introduces a current-mode first-order all-pass filter (APF) and its application in quadrature oscillator (QO) based on CCCII. The proposed filter can provide inverting and noninverting all-pass functions with a same circuit topology, it uses two CCCIIs and one grounded capacitor. Moreover, the first-order all-pass filter was applied in current-mode sinusoidal quadrature oscillators with the design based on block diagrams. The introduced oscillators can provide four phase-quadrature signals which independently control the condition of oscillation (CO) and frequency of oscillation (FO). The proposed oscillators consist of three CCCIIs and two grounded capacitors. The proposed APF and QOs have high output impedance which can directly drive load without additional current buffer. In addition, they use only grounded capacitors which are very appropriate to future development into an integrated circuit. The results of PSPICE simulation program correspond to the theoretical analysis.

In this paper, a new second-order current-mode universal filter using only two plus-type differential voltage current conveyors, three resistors and two grounded capacitors is proposed. The proposed circuit with two identical inputs and three outputs can simultaneously provide second-order high output impedance low-pass, band-pass and notch filter responses. Also, it can realize high-pass and all-pass filter responses with interconnection of relevant output currents. It can be easily tuned electronically. It can be operated properly at high frequencies. A number of simulations based on SPICE program and an experimental test are achieved in order to demonstrate the performance of the proposed filter.

In this paper, a CMOS resistor-based current mirror (RBCM) aimed to be used in low-voltage applications is presented. The main features of the proposed current mirror are very low input voltage requirement (a few mV), low output voltage requirement, high output impedance and simple circuitry. The core structure of the proposed RBCM consists of three transistors (excluding bias circuitry) and two low value grounded resistors. The proposed circuit alleviates the need for cascode structures which are conventionally used to boost the output impedance and linearity. SPICE simulations using 0.18$\mu$m CMOS technology parameters under supply voltage of 0.9V are reported which show input and output voltage requirements of 40mV and 0.1V respectively, low THD of 1.2%, $R_{\mathrm{\text{in}}}$ of 496$\mathrm{\Omega }$, $R_{\mathrm{\text{out}}}$ of 1M$\mathrm{\Omega }$, $-$3dB bandwidth of 181MHz and power dissipation of 154$\mu$W. A high CMRR differential amplifier and a high performance current difference circuit as applications of the proposed RBCM are given. The proposed RBCM is very useful in tackling restrictions of modern technologies such as reduced supply voltage and transistors low intrinsic output impedance.

A proposal of a fractional ($1+\alpha$)-order low-pass filter is presented in this paper. The proposed filter operates in the current-mode and it is designed using Multi-Output Current Followers (MO-CFs), Dual-Output Current Follower (DO-CF), Dual-Output Adjustable Current Amplifier (DO-ACA) and Adjustable Current Amplifiers (ACAs) as active elements within the presented topology of the filter. The filter possesses ability to electronically control its order and also the pole frequency by changing the current gain of current amplifiers (ACAs) already present in the structure. Three different values of the order and pole frequency of the proposed low-pass filter were tested as an example. Design of the proposed filter is supported by simulation and experimental results. Simulations of the circuit are carried out in PSPICE simulator with behavioral models of used active elements. The experimental laboratory measurements are performed with the help of available devices forming equivalent circuits. Simulations and experimental results of the electronical control of the order and pole frequency are compared in this contribution.

This study proposes a new electronically tunable third-order quadrature oscillator using two multi-output voltage difference transconductance amplifiers (VDTAs) and three grounded capacitors. The proposed circuit provides three quadrature voltage outputs, two high-impedance quadrature current outputs, and one high-impedance current output with controllable amplitude. The proposed circuit can provide amplitude modulation/amplitude shift keying signals when the input bias current of the second VDTA is a modulating signal. The oscillation condition and oscillation frequency can be separately adjusted by the input bias currents of two multi-output VDTAs, and it is suitable for use on custom sensor networks. Experimental and H-Spice simulation results are given to confirm theoretical analyses.

In this paper, a compact low-power, high-speed, low-error four-quadrant analog multiplier is proposed using a new simple current squarer circuit. The new squarer circuit consists of an NMOS transistor, which operates in saturation region, plus a resistor. The proposed multiplier has a balanced structure composed of four squarer cells and a simple current mirror. This multiplier also has the important property of not using bias currents which results in greatly reduced power. The performance of the proposed design (for passive and active realization of the resistors) has been simulated using HSPICE software in 0.18$\mu$m TSMC (level-49) CMOS technology. Simulation results with $\pm 0.7$-V DC supply voltages show (for passive realization) that the maximum linearity error is 0.35%, the $-3$dB bandwidth (BW) is 903MHz, the total harmonic distortion (THD) is 0.3% (at 1MHz), and the maximum and static power consumption are $139.25\mu$W and $14.5\mu$W, respectively. Also, post-layout simulation results are extracted, which give the maximum linearity error as 0.4%, the $-3$dB BW as 657MHz and the THD as 0.35%, as well. Moreover, Monte Carlo analysis are performed to verify the satisfactory robustness and reliability of the proposed work’s performance.

This paper deals with the realization of current-mode first-order universal filter based on multiple output second generation current conveyor (MO-CCII). Two MO-CCIIs, one resistor and one capacitor are used in the circuit realization. The proposed work includes additional features such as ease of cascadability, easily implementable in modern integrated circuit technology and no requirement of passive components matching condition. The additional beauty of the proposed filter structure is that all three responses can also be realized by interchanging the positions of passive components as well. Moreover, a possible transformation of the proposed current-mode type universal filter into a voltage-mode type universal filter using network transpose method is also explored. The possibility of mode transformation further expands the scope of proposed idea. The theoretical aspects are verified using cadence VIRTUOSO simulation results.

In this work, a three-input single-output structure of current-mode second-order multifunction filter is presented. Two multiple-output second-generation current conveyors serve as the active building blocks. Additionally, two grounded resistors and two grounded capacitors are employed as passive components. On appropriate selection of the input values, all second-order filter functionalities, namely, low-pass, high-pass, all-pass, band-pass and band-reject, can be availed. Proposed filter shows good sensitivity performance and supports high frequency operation. Non-ideal analysis is presented to show the intactness of filter characteristics under runtime conditions. Simulation results show good correlation with the theoretical performance of the proposed filter.