Non-inverting Lowpass Research Articles

Reconfigurable Voltage-Mode First-Order Multifunction Filter Employing Second-Generation Voltage Conveyor (VCII) With Complete Standard Functions and Electronically Controllable Modification

In this contribution, the realization of a first-order, two-input, single-output voltage-mode multifunction filter employing a second-generation voltage conveyor (VCII) is described. The proposed first-order versatile filter is extremely simple, composed of a single VCII and three passive devices. Because of its low output impedance, the output voltage node can be easily cascaded with other voltage-mode configurations without the requirement of any buffers. In the same circuit topology, the proposed first-order filter provides various filtering functions: inverting and non-inverting low-pass (LPF), inverting and non-inverting high-pass (HPF), as well as inverting and non-inverting all-pass (APF). The digital method allows the selection of output first-order filtering functions without the need for additional circuits such as inverting or double-gain amplifiers. Furthermore, the pass-band gain of the low-pass and high-pass responses can be adjusted by varying the resistance or capacitance values without influencing the pole frequency as well as the phase response. The influence of VCII’s current/voltage gain errors and parasitic elements on filtering performance is also investigated. Moreover, the modification of the proposed lagging phase all-pass filter to achieve electronic controllability is also proposed by replacing the passive resistor with the operational transconductance amplifier (OTA). The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.18\mu \text{m}$ </tex-math></inline-formula> TSMC CMOS structure of the VCII employed in the proposed filter operates in the subthreshold region and utilizes the bulk-driven technique (BD), enabling it to operate with 0.4V supply voltage and consuming 383 nW of power. The total harmonic distortion (THD) of the LPF with an applied input voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$V_{inpp}=300$ </tex-math></inline-formula> mV @ 50Hz is -49.5 dB. An application example as a quadrature sinusoidal oscillator realized from the proposed first-order allpass filter and lossless integrator is also included. The performance of the proposed reconfigurable voltage-mode first-order filter is simulated and experimentally tested using a commercially available AD844 IC-based VCII with ±5 V power supply.

A novel voltage-mode universal second-order filter using five single ended OTAs and its quadrature sinusoidal oscillator application

This study proposes a single-ended operational trans-conductance amplifier (SEOTA)-based triple inputs and single output high-input impedance voltage-mode (VM) universal second-order filter. The proposed universal VM SEOTA-based second-order filter can be realized for the non-inverting low-pass, non-inverting high-pass, non-inverting band-reject, non-inverting all-pass and inverting band-pass filtering functions by appropriately using different triple-input voltage signals. The high-input impedances of the proposed universal VM SEOTA-based configuration enable the second-order filter to be cascaded without additional buffers. The proposed configuration does not employ external resistors and accordingly is an active SEOTAs and capacitors (SEOTA-C) universal second-order filter. The proposed circuit using two grounded capacitors which is more apposite to further develop into an integrated circuit implementation. The resonance angular frequency and quality factor are orthogonal electronically adjustable. By slightly modifying the proposed universal VM SEOTA-based second-order filter configuration, the VM SEOTA-C quadrature sinusoidal oscillator is achieved. The oscillation frequency and the oscillation condition of the quadrature sinusoidal oscillator can be independently and electronically tuned by adjusting the bias currents of two SEOTAs. PSpice simulation results confirmed theoretic anticipation. The result of the experiment of the commercially available SEOTAs, LT1228s, are also used to verify the characteristics of the proposed universal VM SEOTA-based second-order filter and VM SEOTA-based quadrature sinusoidal oscillator.

Design and Experiment of Electronically Tunable Voltage-Mode Biquad and Output Current Amplitude Oscillator

This study presents an electronically tunable configuration for the design of a voltage-mode (VM) biquad with four input terminals and three output terminals. The proposed circuit employs four operational transconductance amplifiers (OTAs) and two grounded capacitors. Depending on the selections of the four input voltage signals, all the standard filtering functions can be realized. The proposed configuration simultaneously provides VM inverting band-pass, non-inverting low-pass, and non-inverting band-reject filtering functions without any component-matching choices. It offers the features of a resistorless structure, high-input impedance, electronic control of the pole frequency and quality factor, and low active and passive sensitivities. The measured power dissipation of the biquad is 0.96 W under 32 mA constant output current. The measured 1 dB power gain compression point of the output inverting band-pass filter is −7 dBm. The measured value of the third-order intercept point is 5.136 dBm, and the measured value of the third-order intermodulation distortion is −50.83 dBc. Moreover, the measured value of the spurious-free dynamic range is 53.49 dB, and the figure-of-merit of the biquad is 268.75 × 103. In addition, an electronically controllable quadrature oscillator (QO) with amplitude of output current can be realized using the proposed biquad. The proposed electronically controllable QO can provide an amplitude modulation signal or an amplitude shift keying signal, and is widely applied in signal processing systems and electronic communication systems. PSpice simulations and experimental results are accomplished.

High-Input Impedance Voltage-Mode Multifunction Filter

This paper proposes a high-input impedance voltage-mode (VM) multifunction biquad filter which employs three current-feedback amplifiers (CFAs), three resistors, and two grounded capacitors. The proposed VM multifunction biquad filter has single-input and triple-output and can realize non-inverting low-pass (NLP), inverting band-pass (IBP), and non-inverting band-stop (NBS) voltage responses at the same time without increasing component selection. The proposed VM multifunction biquad filter enjoys the orthogonal tunability of angular frequency and quality factor and also provides the advantage of using only two grounded capacitors, high-input impedance and low active/passive sensitivity. The performance of the proposed VM multifunction biquad filter is verified through its hardware implementation and OrCAD PSpice simulation based on AD844-type CFAs. The circuit analysis, sensitivity analysis, and NLP, IBP, and NBS voltage responses are also shown in this paper. The paper presents a method to effectively reduce the active and passive components, maintain good circuit performance, and reduce circuit costs.

A Transconductance-Mode Multifunction Filter with High Input and High Output Impedance Nodes Using Voltage Differencing Current Conveyors (VDCCs)

The design of transconductance-mode multifunction biquad filter containing three input voltage nodes and single-output current node is proposed. Its circuit principle is emphasized on employing Voltage Differencing Current Conveyor (VDCC) to be an active building block. The proposed filter description uses three VDCCs co-working with two grounded capacitors and three grounded resistors. The synthesis of the proposed multifunction filter is based on avoidance of using multiple-output active elements to achieve commercially available integrated circuits for practical implementation. Additionally, without multiple-output active element, it can alleviate current tracking error from the current mirrors used in output ports. It also decreases the amounts of the transistors inside the active elements. The proposed multifunction filter offers all 5 filter functions, which are non-inverting Low-Pass (LP), non-inverting High-Pass (HP), non-inverting Band-Pass (BP), non-inverting Band-Reject (BR) and also non-inverting All-Pass (AP) functions from same circuit topology under different circuit condition for input signals. Furthermore, the natural frequency for all filtering responses is independently achieved from the bandwidth or the quality factor of the proposed filter. For cascade-able connectivity, the output current port indeed provides a high impedance. In addition, the magnitude of the output current for all filtering functions can be resistively adjusted. The consideration for non-ideal case of the presented multifunction filter is also analyzed. The simulation and experimental results of the presented transconductance multifunction biquad filter based on VDCC practically implemented by the commercially available ICs, LM13700 and AD844 can validate the theoretical anticipation.

A voltage-mode universal filter using five single-ended OTAs with two grounded capacitors and a quadrature oscillator using the voltage-mode universal filter

A new voltage-mode universal filter using five single-ended operational transconductance amplifiers (OTAs) with two grounded capacitors and a quadrature oscillator using the proposed voltage-mode universal filter is presented in this paper. The proposed circuit can provide non-inverting lowpass, bandpass, highpass, bandreject and allpass filters, and inverting bandpass and highpass filters by appropriately applying different five input voltage signals. The circuit only employs five single-ended OTAs with two grounded capacitors to maintain the following advantages: (i) orthogonal electronic tunable resonance angular frequency and quality factor without control factor matching conditions, (ii) no resistors required, (iii) high-input impedance, (iv) no extra inverting or non-inverting amplifiers for special input signals, and (v) low active and passive sensitivities. Besides, the proposed filter can be used to implement a quadrature sinusoidal oscillator with independently controlled oscillation condition and the oscillation frequency. OrCAD PSpice simulation and experimental results of commercially available OTAs, LT1228, are used to confirm the characteristics of the proposed voltage-mode universal filter and quadrature sinusoidal oscillator.

A CFOA-Based Voltage-Mode Multifunction Biquadratic Filter and a Quadrature Oscillator Using the CFOA-Based Biquadratic Filter

This paper proposes a new high-input impedance current feedback operational amplifier (CFOA)- based voltage-mode multifunction biquadratic filter and a voltage-mode quadrature oscillator using the proposed high-input impedance CFOA-based biquadratic filter. The proposed high-input impedance CFOA-based voltage-mode multifunction biquadratic filter uses three CFOAs, three resistors, and two grounded capacitors with two inputs and three outputs. The filter can simultaneously realize non-inverting low-pass, non-inverting band-pass, and non-inverting band-reject filtering functions at the high-input impedance terminal while the inverting band-pass and non-inverting high-pass filtering functions can also be obtained by applying another high-input impedance terminal. The filter offers orthogonal control of resonance angular frequency and quality factor. The proposed high-input impedance CFOA-based voltage-mode multifunction biquadratic filter can be used to implement a voltage-mode quadrature oscillator with an independently controlled the frequency of oscillator and the condition of oscillation. The OrCAD PSpice simulation and experimental results of the commercially available integrated circuit, AD844AN, are used to confirm the characteristics of the proposed filter and oscillator.

Versatile Tunable Voltage-Mode Biquadratic Filter and Its Application in Quadrature Oscillator.

This paper presents a versatile tunable voltage-mode biquadratic filter with five inputs and three outputs. The proposed filter enjoys five single-ended output operational transconductance amplifiers (OTAs) and two grounded capacitors. The filter can be easily transformed into a quadrature oscillator. The filter with grounded capacitors is resistorless and electronically tunable. Either a voltage-mode five-input single-output biquadratic filter or a voltage-mode single-input three-output biquadratic filter can be operated by appropriate selecting input and output terminals. In the operation of five-input single-output biquadratic filter, the non-inverting lowpass, non-inverting bandpass, inverting bandpass, inverting highpass, non-inverting bandreject, inverting bandreject, and non-inverting allpass filtering responses can be realized by appropriately applying the input voltage signals. In the operation of single-input three-output biquadratic filter, the non-inverting/inverting lowpass, bandpass and bandreject filtering responses can be realized simultaneously. The circuit provides independent adjustment of the resonance angular frequency and quality factor, high-input impedance, and no inverting-type input voltage signals are imposed. The application in quadrature oscillator exhibits independent electronic tuning characteristic of the oscillation condition and the oscillation frequency. The theoretical analysis has been verified through OrCAD PSpice and furthermore by experimental measurements.

A systematic realization of third-order quadrature oscillator with controllable amplitude

A systematic realization of third-order quadrature oscillator using a voltage-mode non-inverting lowpass filter and a voltage-mode inverting lossless feedback integrator is presented in this paper. The proposed circuit consists of two multiple-output differential voltage current conveyor transconductance amplifiers (MO-DVCCTAs), two grounded resistors and three grounded capacitors. The new circuit provides three quadrature voltage outputs, two high-impedance quadrature current outputs, and one high-impedance current output with controllable amplitude, simultaneously. When the input bias current of the first MO-DVCCTA is a modulating signal, the circuit can generate amplitude modulation or amplitude shift keying signals. The condition of oscillation and the frequency of oscillation can be controlled independently through grounded resistors. The proposed circuit only uses grounded capacitors and grounded resistors, which can be easily implemented as an integrated circuit. The experimental results and H-Spice simulation results are given to confirm the theoretical analysis.

Voltage-mode multifunction biquadratic filter with one input and six outputs using two ICCIIs.

A novel voltage-mode multifunction biquadratic filter with one input and six outputs is presented. The proposed circuit can realize inverting and noninverting low-pass, bandpass, and high-pass filters, simultaneously, by using two inverting second-generation current conveyors (ICCIIs), two grounded capacitors, and four resistors. Moreover, the proposed circuit offers the following attractive advantages: no requirements for component matching conditions, the use of only grounded capacitors, and low active and passive sensitivities. HSPICE and MATLAB simulations results are provided to demonstrate the theoretical analysis.

High-Input Impedance Voltage-Mode Multifunction Filter with Four Grounded Components and Only Two Plus-Type DDCCs

This paper introduces a novel voltage-mode multifunction biquadratic filter with single input and four outputs using two plus-type differential difference current conveyors (DDCCs) and four grounded passive components. The filter can realize inverting highpass, inverting bandpass, noninverting lowpass, and noninverting bandpass filter responses, simultaneously. It still maintains the following advantages: (i) using grounded capacitors attractive for integration and absorbing shunt parasitic capacitance, (ii) using grounded resistors at allXterminals of DDCCs suitable for the variations of filter parameters and absorbing series parasitic resistances at allXterminals of DDCCs, (iii) high-input impedance good for cascadability, (iv) no need to change the filter topology, (v) no need to component-matching conditions, (vi) low active and passive sensitivity performances, and (vii) simpler configuration due to the use of plus-type DDCCs only. HSPICE and MATLAB simulations results are provided to demonstrate the theoretical analysis.

New Bandpass-lowpass Filters Using CC II

Two new bandpass-lowpass filters are presented. Each circuit employs two opposite polarity current conveyors and realizes an inverting bandpass and a non-inverting lowpass response. The design equations for each circuit are given.

Active R multifunction circuit synthesis

A synthesis technique for an active R multifunction circuit is presented. The realised circuit provides inverting bandpass, noninverting lowpass, allpass, band elimination and oscillator functions. With polarities of both the operational amplifiers (OAs) reversed, noninverting bandpass, noninvertig lowpass and oscillator functions are realised. The circuit has been analysed, based on a simplified pole-zero model for the OAs.