Current-mode Filter Research Articles

0.5 V, Low-Power Bulk-Driven Current Differencing Transconductance Amplifier

This paper presents a novel low-power low-voltage current differencing transconductance amplifier (CDTA). To achieve a low-voltage low-power CDTA, the BD-MOST (bulk-driven MOS transistor) technique operating in a subthreshold region is used. The proposed CDTA is designed in 0.18 µm CMOS technology, can operate with a supply voltage of 0.5 V, and consumes 1.05 μW of power. The proposed CDTA is used to realize a current-mode universal filter. The filter can realize five standard transfer functions of low-pass, band-pass, high-pass and band-stop, and all-pass from the same circuit. Neither component-matching conditions nor input signals of the inverse type are required to realize these filter functions. The current-mode filter offers low-input and high-output impedance and uses grounded capacitors. The natural frequency and quality factor of the filters can be orthogonally controlled. The proposed CDTA and its applications are simulated using SPICE to confirm the feasibility and functionality of the new circuits.

Single EX-CCCII-Based First-Order Versatile Active Filter

This paper presents a new current-mode first-order versatile active filter employing one extra-x second-generation current controlled current conveyor (EX-CCCII) and one grounded capacitor. The proposed filter can realize first-order filtering functions of a low-pass filter (LPF), high-pass filter (HPF), and all-pass filter (APF) within the same topology with low-input and high-output impedances required for current-mode circuits. This multiple-output EX-CCCII-based filter can provide six transfer functions as both non-inverting and inverting filtering functions of the LPF, HPF, and APF are obtained. The filter also offers electronic control of the pole frequency of all filtering. The proposed current-mode filter can be applied to work as a mixed-mode active filter, namely in the transadmittance-mode (TAM), transimpedance-mode (TIM), and voltage-mode (VM). Each operation mode can provide six transfer functions. The proposed filter was simulated and designed using SPICE and 0.18 µm CMOS technology. Experimental results using the commercially available integrated circuit AD844 were used to confirm the functionality of the new circuits.

VCII based electronically tunable multi‐mode filter structure with fourth order low‐pass function for the HF band applications

SummaryIn this paper, we propose an electronically tunable multi‐mode filter structure with fourth‐order current mode low‐pass function based on second‐generation voltage conveyor (VCII) for the analog baseband applications. The fourth‐order low‐pass circuit consists of second‐order core filter structures including band and low‐pass outputs. The proposed fourth‐order circuit's cut‐off frequency can be easily varied from 1.6 up to 17.2 MHz for the high frequency (HF) applications used in multi‐standard receivers. Also, the core circuit of the fourth‐order architecture possesses current mode and transresistance mode filter functions enabling signal conversion and different signal operations. The given architecture has 116 μm × 39 μm chip area, and post layout simulations are demonstrated extensively. In addition, the performance of the proposed structure is examined based on commercial elements (AD844s). Also, detailed linearity analysis is given using post layout extractions. In fourth‐order low‐pass structure, cut‐off frequency can be safely tuned from 1.6 up to 17.2 MHz, whereas consumed power can be reduced to 0.769 μW. It can be investigated that the proposed circuit can be safely used for the analog baseband and HF operations in wireless receivers.

Metamutator based universal, single input multi output current mode filter

AbstractThe introduction of Add ‐ Differentiate IC, AD‐IC, a new integrated circuit, into schemes for realizing single input multiple output current mode filters is the motivation behind this paper. In the circuit structure of this filter with only one active device with a minimal number of transistors and five passive components are being used. Non ideal effects of the design are investigated and simulation results of the application, using TSMC 0.25 μm process parameters with ±1.25 V power supply voltage and the bias as 0.8 V resulting in 0.99 mW power dissipation for the entire filter, are also presented to confirm the theoretical analysis. With this new design technique, the tunabilities of the angular frequency ( ) and quality factor ( ) can be performed independently.

MOSFET-C current mode filter for secure communication applications

In this paper, a dual output current-mode biquad filter with band-pass and low-pass outputs using MOS transistors and capacitors is presented. In these type of filters MOSFETs operating in saturation mode are used instead of standard active elements and transconductances of these transistors are utilized instead of resistors. In the study a voltage controlled current source (VCCS) based core filter circuit is presented. This circuit is used as a starting point for the complete filter design. After VCCSs are replaced by MOSFETs biased for operating in saturation region, a resistorless MOSFET-C type filter circuit is obtained with only seven transistors and two grounded capacitors. Also, an agile filter application for secure communication is given to illustrate the functionality.

Frequency Response of Electronically Tunable Current-Mode Third Order High Pass and Low Pass Filter for Q = 10

The circuits using current-mode (CM) building blocks have received considerable attention in many filtering and signal processing applications. Compared to their voltage-mode(VM) counterparts, the current-mode building blocks are attractive because of their wider bandwidth, higher slew rate, and lower power consumptions. In IC technology, it is desirable to operate circuits at low voltages which can be achieved by using CM building blocks. As a large number of op-amp based circuits with elegant realization procedures are already available, it is worthwhile to convert them into the circuits based on current-mode building blocks. In this paper, a realization of a current mode third order high pass and low pass filter is described. The proposed circuit employs operational amplifier as the basic building unit. The filter circuit realizes quadratic work function. It provides electronically tuning capability of the filter characteristics. The proposed circuit works ideal for Center frequency fo= 10 k and Circuit merit factor Q > 1. The gain roll-off this configuration is 18dB/octave. The circuit is suitable for monolithic integration and high frequency operation. The filters developed were successful in obtaining passive sensitivities less than unity in magnitude and active sensitivities are half in magnitude, which is a noteworthy achievement. The circuit is suitable for high frequency operation and monolithic integration.

Electronically Tunable Third Order Feed Forward CM Band Pass Filter for Q = 10

A new electronically tunable current-mode third order filter is proposed in this paper. OP-AMP is used as an active building block. With current input the filter can realize band pass responses in current mode. The filter circuit realizes calculated transfer function. The other attractive features of the filter are a) Employment of minimum active and passive elements b) Responses are electronically tunable c) Low active and passive sensitivities d) Suitable for high frequency operation e) Ideal for integrated circuit implementation.

Electronically Tunable SIMO type Mixed-mode Biquadratic Filter using Single FTFNTA

In this manuscript, a new electronically tunable single input multiple output (SIMO) type mixed-mode biquad filter is proposed. It comprises of single Four Terminal Floating Nullor Transconductance Amplifier (FTFNTA) as an Active Building Block, one resistor, and two grounded capacitors. The proposed design can generate current mode (low-pass, high-pass, and band-pass) filters and transimpedance mode (band-pass and inverting low-pass) filters simultaneously for current as an input. Similarly, for voltage as input, it can generate voltage mode (high-pass and inverting band-pass) filters and transadmitance mode (inverting band-pass and inverting high-pass) filters simultaneously. The pole frequency (ω 0 ) and quality factor (Q 0 ) can be tuned electronically as well as through a grounded capacitor without disturbing the bandwidth (ω 0 /Q 0 ). Design is independent from the input as well as passive component matching constraint. The presence of grounded capacitors makes the circuit feasible for IC realization. The functionality of the proposed design is validated through PSIPCE simulation. To check the robustness of the proposed design Monte Carlo, sensitivity, and noise analysis is also performed.

A Novel Current Mode Multifunction Inverse Filter using Single CFA

A novel current-mode multifunction inverse filter configuration using single current feedback amplifier (CFA) is presented. The proposed filter employs only one CFA and few passive components. The proposed circuit realizes inverse lowpass, inverse bandpass and inverse highpass filter functions with proper admittances. The characteristics of proposed multifunction inverse filter configuration are- current-mode realization; use of only one CFA; use of grounded passive components except one virtually grounded and realizing all three basic inverse filters. The proposed current-mode inverse filter circuit has been tested by TINA PRO simulation program and results justified the theoretical analysis.

The design of low voltage/power current-mode sinh-domain filter for biomedical applications

The design of low voltage/power current-mode sinh-domain filter for biomedical applications

CNTFET‐based active grounded inductor using positive and negative current conveyors and applications

AbstractIn this work, we design and simulate novel 32 nm carbon nanotube field effect transistor (CNTFET) as well as complementary metal oxide semiconductor (CMOS)‐based negative class AB second generation current conveyors (CC) (CNTFET‐CCII and CMOS‐CCII−). The comparative analyses of various performance measuring parameters of both these CCII's have been performed. A significant improvement in current and voltage bandwidths, terminal X and Y impedances at lesser total harmonic distortions and reduced power consumption have been observed in the proposed CNTFET‐based CCII− in comparison to its CMOS‐based counterpart. Further, a CNTFET‐based active grounded inductor (AGI) has been designed and simulated for the first time using the proposed CNTFET‐CCII− and our recently designed CNTFET‐CCII+ and has been compared with the CMOS‐based AGI. To validate the performance of the simulated AGI's, single input multi output current mode filter and third‐order high pass Butterworth filter have also been designed and simulated. The simulation results reveal that the performance of the CNTFET‐AGI‐based applications are close to ideal response with less power consumption and temperature insensitivity with reduced active chip die area of 0.16 μm2 and can be efficiently used for low voltage, low power, and high frequency applications.

Realization of Generalized Current-Mode Multifunction Filter

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.

Dual-mode multifunction filter realized with a single voltage differencing gain amplifier (VDGA)

This article presents the dual-mode multifunction biquad filter realized employing only a single voltage differencing gain amplifier (VDGA), one resistor and three capacitors. The proposed filterwith one input and three outputs can configure as voltage-mode or current-mode filter circuit with the appropriate input injection choice. It can also synthesis the three standard filter functions, which are highpass, bandpass, and lowpass responses without modifying the circuit configuration. Orthogonal adjustment between the natural angular frequency (o) and the quality factor (Q) of the filter is achieved. Detail analysis of non-ideal VDGA effects and circuit component sensitivity are included. The circuit principle is verified by means of simulation results with TSMC 0.35-m CMOS process parameters.

Electronically Tunable Mixed-Mode Universal Filter Employing a Single Active Block and a Minimum Number of Passive Components

A recently developed active building block, namely Voltage Differencing Extra X Current Conveyor (VD-EXCCII), is employed in the design of multi input single output (MISO), electronically tunable mixed-mode universal filter. The filter provides low pass (LP), high pass (HP), band pass (BP), band reject (BR) and all pass (AP) responses in current-mode (CM), voltage-mode (VM), trans-impedance-mode (TIM) and trans-admittance-mode (TAM). The filter employs a single VD-EXCCII, three resistors and two capacitors. Additionally, a CM single input multi output (SIMO) filter can be derived from the same circuit topology by only adding current output terminals. The attractive features of the filter include: (i) the ability to operate in all four modes, (ii) the tunability of the Q factor independent of pole frequency, (iii) the low output impedance for the VM filter, (iv) the high output impedance current output for CM and TAM filters and (v) no requirement for double/negative input signals (voltage/current) for response realization. The VD-EXCCII and its layout is designed and validated in Cadence Virtuoso using 0.18 µm pdk from Silterra Malaysia with a supply voltage of ±1.25 V. The operation of the filter is examined at the 8.0844 MHz characteristic frequency. A non-ideal parasitic and sensitivity analysis is also carried out to study the effect of process and components spread on the filter performance.

Improved current-mode wave active filter

ABSTRACT In this paper, a resistorless improved wave active filter (WAF) is presented using a comparatively new current-mode building block, namely extra X current-controlled current conveyor (EX-CCCII). The proposed wave active filter is designed in the current mode. The incident and reflected waves are used for designing the basic wave active elements, namely series and shunt inductors (L) and capacitors (C). The novelty of the circuit is that the mathematical operations like lossy integrator, unity gain amplifier, summation, and subtraction, required to realise the wave active elements, are accomplished by judiciously using the port relationships of EXCCCII. As a result of which the proposed circuit is compact and uses only two EXCCCIIs and one grounded capacitor for the realisation of wave elements (L and C). One 3rd and one 4th order Butterworth wave active filters are designed using EX-CCCII-based wave elements and simulated in cadence using 0.18 µm TSMC CMOS technology. The comparison indicates that the proposed WAF uses minimum numbers of analog building blocks (ABBs) and consumes the least power; moreover, the performances such as noise, percentage total harmonic distortion (%THD), and electronic controllability of cut-off frequency of the filters are also reported. Abbreviations: ABB: analog building block; FDNR: frequency-dependent negative resister; WAF: wave active filter; THD: total harmonic distortion; OTA: operational transconductance amplifier; CFOA: current feedback operational amplifier; VDTA: voltage differencing transconductance amplifier; OTRA: operational transresistance amplifier; CCDDCCTA: current-controlled differential difference current conveyor transconductance amplifier; DVCCCTA: differential voltage current-controlled conveyor transconductance amplifier; DVCCTA: differential voltage current conveyor transconductance amplifier; EX-CCCII: extra X current-controlled conveyor

Minimum MOS Transistor Count Fractional-Order Voltage-Mode and Current-Mode Filters

Voltage-mode and current-mode fractional-order filter topologies, which are capable of realizing various types of transfer functions, are introduced in this paper. Thanks to the employment of the transconductance parameter of the MOS transistors, the derived filter structures offer the benefit of the electronic adjustment of their frequency characteristics. With regards to the literature, the number of MOS transisitors is minimized leading to significant reduction of the circuit complexity and power dissipation. Simulation results, derived using the Design Kit of the 0.35 μm Austria Mikro Systeme CMOS process and the Cadence IC design suite, confirm the correct operation of the presented filter structures.

CMOS Implementation of Current Differencing Operational Amplifier and Its Notch Filter Application

Active elements are fundamental circuits for a wide scope of scientific and industrial processes. Many researchers have examined active devices to implement filters, oscillators, rectifiers, and converters. This paper presents the current differencing operational amplifier (CDOA) as an active element, firstly implemented with CMOS transistors. The input part of this circuit is a current differencing unit and the conventional operational amplifier (Op-Amp) pursues it. A new realization of a notch filter consists of CDOA is suggested. Voltage-mode band-pass filter and current-mode notch filter are presented as a different filter applications. Simulation results using TSMC 0.18-[Formula: see text]m CMOS process model are used to verify the theoretical analyses. The sensitivity, noise, total harmonic distortion (THD) and the Monte Carlo analysis have been performed to demonstrate the effectiveness of the proposed active element and notch filter.

Design and Implementation of Biquad Filters Using CMOS Circuit Based Active Elements

This paper mainly concentrates on a new kind of CMOS implementation based on Current Differencing Current Conveyer (CD-CC). The grate CMOS circuit effort is fulfilled by introducing a new kind of biquad filter. The proposed filter employs two CD-CC circuits and four passive elements. The filter is designed depending on Multi Input Single Output (MISO) configuration and realizes all filter functions identified by current mode (Low pass, Band pass, High pass, Band Stop, and all Pass) filter. In addition, the behavior of the proposed filter circuit has been tested and simulated then it results in sound outcomes. This test has been achieved by using the current mode application example, which consists of two (CDCCs) and four passive elements with multi- inputs and a single output. Finally, the filters are simulated using TSMC 0.35 μm technology. Moreover, the theoretical analyses agree with PSPICE simulation results.

Simple Three-Input Single-Output Current-Mode Universal Filter Using Single VDCC

This paper presents a second-order current-mode filter with three-inputs and single-output current using single voltage differencing current conveyors (VDCC) along with one resistor and two grounded capacitors. The design of presented filter emphasizes on the use of a single active element without the multiple terminals VDCC which is convenient to implement the VDCC using commercially available IC for the practical test. Also, it can reduce the current tracking error at current output port and can reduce the number of transistor in the VDCC. The proposed filter can realize all the five generic filter responses, namely, band-pass (BP), band-reject (BR), low-pass (LP), high-pass (HP), and all-pass (AP) functions from the same configuration under various conditions in terms of three input current signals. Furthermore, the natural frequency and quality factor are electronically controlled. The output current node exhibits high impedance. Besides, the non-ideal case is also investigated. The simulation and experimental results using VDCC constructed from commercially available IC can validate the theoretical analyses.

Single DDCC based new immittance function simulators employing only grounded passive elements and their applications

Two grounded immittance function simulators (IFSs) employing only grounded passive elements and one differential difference current conveyor are developed in this paper. Two floating IFSs are obtained from the grounded ones. A current-mode (CM) filter, a voltage-mode (VM) band-pass (BP) filter and a quadrature oscillator (QO) are derived from the first developed grounded IFS. However, for proper operation, all of the circuits except the BP filter and the QO in this study need a single resistive matching condition. Simulations of the CM and VM filter circuits as well as the QO are accomplished through SPICE program. Furthermore, as an example, so as to confirm the performance of the VM filter, an experiment is included.