A State Variable Method for the Realization of Universal Current-Mode Biquads

A state variable method of converting single-resistance-controlled- oscillators (SRCO), into universal current-mode biquad (offering realizations of all the five standard filter functions namely, low pass, band pass, high pass, notch and all pass) has been highlighted. The workability of the exemplary implementation of the derived current-mode universal biquad has been demonstrated by PSPICE simulation results based upon 0.35 μ m technology. It is expected that the proposed method can be applied to other SRCOs to generate other multifunction filter structures.

A Positive Type DVCC-Based Universal Biquad

This paper presents a current-mode universal biquad employing only positive type DVCCs(differential voltage current conveyors).The circuit enables LP(low-pass),BP(band-pass),HP(high-pass),BS(band-stop)and AP(all-pass)responses by the selection and addition of the input and output currents without any component matching constraints.Moreover the circuit parametersω0 and Q can be set orthogonally adjusting the circuit components.A design example is given together with simulation results by PSPICE.

可编程模拟器件的研究与应用

本文介绍了lattice半导体公司推出的可编程模拟器件ispPAC10的内部结构原理及在信号调理方面的应用。详细地阐述了该控制芯片灵活、多变的放大、滤波及衰减功能，并讨论了每种功能的设计方法。

Single MO-CCCCTA-Based Electronically Tunable Current/Trans-Impedance-Mode Biquad Universal Filter

This paper presents an electronically tunable current/trans-impedance-mode biquad universal filter employing only single multi-output current controlled current conveyor trans-conductance amplifier (MO-CCCCTA) and two grounded capacitors. The proposed filter realizes all the standard filter func-tions i.e. low pass (LP), band pass (BP) and high pass (HP), notch and all pass (AP) filters in the current form at high impedance output through appropriate selection of the input signals, without any matching conditions. Simultaneously, it can also realize all the standard filter functions in trans-impedance form from the same circuit topology. The circuit does not require inverting-type input current signal(s) and double input current signal(s) to realize all the responses in the design. The validity of proposed filter is verified through PSPICE simulations.

VDTA Based Electronically Tunable Voltage-Mode and Trans-Admittance Biquad Filter

In this paper, a biquad filter configuration based on two voltage differencing transconductance amplifiers (VDTAs) as newly active elements and only two capacitors as passive elements is proposed which can realize voltage-mode low pass (LP), band pass (BP), high pass (HP), band reject (BR) and all pass (AP) filtering responses using three voltage inputs. Simultaneously, the same configuration can also be used to obtain LP, BP and HP filtering responses in transadmittance-mode. The proposed biquad is capable of providing electronic control of quality factor independent of pole frequency through single transconductance parameter (biasing current). It also offers the advantage of low active and passive sensitivity. To support the theoretical analysis, the PSPICE simulation of the proposed circuit is done using 0.18 μm CMOS technology from TSMC.

An Active-Only Temperature-Insensitive Current-Mode Biquad Filter Based on Differentiator Structures Employing CCCCTAs

This article presents an active-only current-mode universal biquad filter performing three standard functions: low-pass, high-pass and band-pass function, which can be readily modified to achieve the rest functions (band-stop and all-pass). The circuit principle is based on active-only circuit designed by using differentiators which are constructed from current controlled current conveyor transconductance amplifier (CCCCTA) cooperating with an internally frequency compensated operational amplifier (OA). The features of the circuit are that: the pole frequency and quality factor can be independently tuned via the input bias currents and it is ideally temperature-insensitive, its circuit description is very simple, consisting of 3 CCCCTAs and 2 operational amplifiers, and the proposed circuit is very appropriate for further developing into integrated circuit architecture. The PSpice simulation results are shown. The given results agree well with the theoretical anticipation.

Universal Current-Controlled Current-Mode Biquad Filter Employing MO-CCCCTAs and Grounded Capacitors

This paper presents a universal current-controlled current-mode biquad filter employing current controlled current conveyor trans-conductance amplifiers (CCCCTAs). The proposed filter employs only three MO- CCCCTAs and two grounded capacitors. The proposed filter can simultaneously realize low pass (LP), band pass (BP), high pass (HP), band reject (BR) and all pass (AP) responses in current form by choosing appropriate current output branches. In addition, the pole frequency and quality factor of the proposed filter circuit can be tuned independently and electronically over the wide range by adjusting the external bias currents. The circuit possesses low active and passive sensitivity performance. The validity of proposed filter is verified through PSPICE simulations.

A Plus Type CC-Based Current-Mode Universal Biquad

This paper introduces a current-mode universal biquad circuit using only plus type CCs(current conveyors)(i.e.DVCCs(differential voltage current conveyors)and CCIIs(second generation current conveyors)).The circuit enables LP(low-pass),BP(band-pass),HP(high-pass),BS(band-stop)and AP(all-pass)responses by the selection and/or addition of the input and output currents without any component matching constraints.Moreover the circuit parametersω0 and Q can be set orthogonally adjusting the circuit components.A design example is given together with simulation responses by PSPICE.

A VERSATILE CURRENT-MODE BIQUAD USING OPERATIONAL AMPLIFIERS

A versatile current-mode biquadratic filter using three operational amplifiers and nine passive elements is proposed. By suitably choosing the output branch, lowpass, bandpass, highpass, bandstop and allpass transfer functions are realized simultaneously without changing the circuit configuration and elements. Two circuits, one is for low frequency application and the other for high frequency, are proposed. The center frequency, quality factor and gain constants of the circuit can be tuned independently. Simulated results show that the circuits work successfully.

Design of Sixth-Order Lowpass Elliptic Switched-Capacitor Filter

In this paper the design and implementation of sixth-order lowpass elliptic switched-capacitor filter( SCF) for interface circuit of Micro-Electro-Mechanical System( MEMS) sensor are presented. This work aims to lower total harmonic distortion( THD) without deteriorating other performances. After system design in Simulink,the filter is realized in transistor level and finally fabricated in Central Semiconductor Manufacturing Corporation( CSMC) 0.5 μm metal-oxide-semiconductor( CMOS) technology. Typical measured results are: it operates with 25: 1 clock-to-corner frequency ratio and a 10 k Hz maximum corner frequency. The maximum passband ripple is about 0.49 d B and the minimum stopband rejection is 40 d B for the temperature from-20 ℃to 80 ℃. For the 250 k Hz clock frequency setting,given the 1 k Hz,- 8 d BVrms input signal,the measured worst case THD is-64 d B. The active area of the chip is 2.8 mm2 with 8 pads. The analog power dissipation is10 m W from a 5 V power supply.

Design of Fading Channel Simulator Based on IIR Filter Using Genetic Algorithm

This article designs a Rayleigh fading channel simulator using IIR filter (called Doppler filter), which is used to approximate the Jakes Doppler spectrum. We mainly focus on the design of Doppler filter and model it as an optimization problem. Non-convexity of the problem is proved in this paper and genetic algorithm (GA) is used to optimize it, which has never been used before in this area. Simulation result shows that GA converges at the solution corresponding to very accurate approximation of Jakes PSD. Finally, several statistical characteristics of the simulator are verified, including correlation functions and level-crossing rate (LCR), all of which match the theoretical predictions pretty well.

A Novel Plus Type DVCC-Based Current-Mode Biquad

This paper presents a novel current-mode biquad using only plus type DVCCs(differential voltage current conveyors).The circuit enables LP(low-pass),BP(band-pass),HP(high-pass),BS(band-stop)and AP(all-pass)responses by the selection and/or addition of the circuit currents with no component matching constraints.Moreover the circuit parametersω0 and Q can be set orthogonally adjusting the circuit components.An achievement example is given together with simulation results by PSPICE.

CM-Biquad Filter Using Single DO-VDBA

In this manuscript we present a current mode biquad using one dual output-voltage differencing buffered amplifier (DO-VDBA) and four passive components (2 grounded capacitors and 2 resistors). The proposed circuit offers very low active and passive sensitivity. The filter presented here is electronically tunable, frequency of oscillation (FO) can be tuned by controlling transconductance (gm) by varying the bias current (IB) of the circuit. The workability of proposed circuit is tested using PSPICE with 180 nm TSMC CMOS process parameters.

Voltage-Mode Lowpass, Bandpass and Notch Filters Using Three Plus-Type CCIIs

A single input and three outputs voltage-mode biquadratic filter using three plus-type second-generation current conveyors (CCII), two grounded capacitors and five resistors is presented. The proposed circuit offers the following features: realization of three filter functions, which are, lowpass, bandpass and notch filters, simultaneously, the use of only grounded capacitors. PSPICE simulation results are also included.

Switched Capacitor Biquad Filter Using CDTA

A switched capacitor biquad filter using current differencing transconductance amplifier (CDTA) is presented in this paper. The proposed circuit employs only one CDTA, two virtually grounded capacitors and one switched capacitor. It is a resistorless circuit, so it is beneficial to IC implementation in terms of space consideration. The proposed circuit is a second order single input multiple output (SIMO) current-mode filter. This filter can simultaneously realize all basic filter functions high pass, low pass and band pass responses without any component-matching conditions. All the active and passive sensitivities are low. The natural angular frequency (ω0) and quality factor (Q) of proposed filter can be electronically controlled. Owing to current mode operation it consumes less power. PSPICE simulation results are used to verify the theoretical analysis.

Current Processing Current Tunable Universal Biquad Filter Employing Two CCTAs and Two Grounded Capacitors

This paper presents a current processing current-tunable universal biquad filter employing two current conveyor transconductance amplifiers (CCTAs) as active element and two grounded capacitors as passive element. It realizes all the five standard filtering responses such as low pass (LP), band pass (BP), high pass (HP), band reject (BR) and all pass (AP) through appropriate selection of applied current inputs. Proposed circuit does not require minus input current signal and double input current signal to realize different filtering responses. It also does not require component matching condition to realize any filtering responses. Moreover, the circuit offers the advantage of orthogonal electronic tunability of pole-frequency and quality factor. The circuit exhibits low active and passive sensitivities. The circuit performance is verified through P-SPICE simulation software.

Realization of a New Current Mode Second-Order Biquad Using Two Current Follower Transconductance Amplifiers (CFTAs)

A new circuit for realization of universal current-mode filter using current Follower Transconductance Amplifiers (CFTAs) is presented. The proposed circuit realizes current-mode low pass, high pass and band pass filter functions simultaneously with a single current source at the input. The band reject and all pass filters can also be obtained from the proposed circuit without any extra hardware. The proposed circuit employs three passive grounded elements and two CFTAs. Linear electronic control of natural frequency ω0 is available in the proposed circuit. The quality factor can be independently adjusted through grounded resistor. The proposed circuit employs two grounded capacitors and a grounded resistor along with two CFTAs. The grounded resistor can be replaced by an OTA based circuit for linear electronic control of quality factor Q0. The circuit exhibits low active and passive sensitivities for ω0 and Q0. Simulation results are obtained using PSPICE software which is in conformity with the theoretical findings.

A Mixed-Mode Biquad Employing OTAs and Grounded Capacitors

This paper introduces a mixed-mode biquad employing OTAs （operational trans-conductance amplifiers） and grounded capacitors. The circuit can perform mixed-mode operation by selecting the input and output terminals. Additionally, the circuit enables low-pass, band-pass, high-pass, band-stop and all-pass transfer functions suitably choosing the input terminals. The circuit parameters ω0 and Q can be tuned orthogonally through adjusting the trans-conductance gains of the OTAs. The biquad enjoys very low sensitivities with respect to the circuit active and passive components. The achievement examples are given together with simulation results by PSPICE.

有源滤波器的一种设计方法——四运放BIQUAD的应用

随着电子科学的急速发展,电子器件已向小形化、功能全的方向发展。本文介绍一种设计有源网络的实用方法,并通过实际验证,表明这套计算方法是非常有价值的。在文章中介绍了应用最为普遍的考尔切比雪夫型滤波器,因为对给定的滤波器技术要求,它所需要的阶数最低。