Design Of Low-pass Filter Research Articles

0.342 nW Class-AB enhanced flipped source follower low pass filter for biomedical applications.

Owing to the impact of process voltage and temperature variations, the design of low-power low-pass filters (LPFs) with improved linearity is still one of the most challenging tasks for effective biological signal processing. This paper presents the design of a fourth-order Class-AB enhanced flipped source follower (EFSF) LPF circuit aimed at the detection of electroencephalography signals. The simulated results attained using complementary metal-oxide-semiconductor 180nm technology node in Cadence Analog Design Environment demonstrate that the EFSF LPF emulates a DC-gain of -88 mdB with a bandwidth of 100Hz and consumes 0.342 nW power from a supply voltage of 0.5V. The calculated figure of merit for the proposed filter is 5.983 × 10-15J with a dynamic range (DR) of 43.54 dB and input-referred noise of 91 µVrms. It consumes an area of 0.0458mm2. To check the robustness of the proposed filter circuit, we performed Monte Carlo simulations with 200 runs. The statistical results achieved for the DC-gain, DR, and total harmonic distortion of the proposed filter show mean values of -188.09 mdB, 43.10 dB, and -41.85 dB along with standard deviation values of 285.21 mdB, 718.72 mdB, and 4.52 dB, respectively. The proposed Class-AB EFSF LPF can be used to achieve high power efficiency in future low-voltage and low-power biological systems.

The development a fully-balanced current-tunable first-order low-pass filter with Caprio technique

This paper presents the development and design of a fully-balanced current-tunable first-order low-pass filter with Caprio technique, which could include the design and implementation of a first-order low-pass filter circuits. The filter consists of six bipolar junction transistor (BJT) and a single capacitor. The filter construction uses a bipolar junction transistor (BJT) as the main device and a single capacitor. A fully-balanced current-tunable first-order low-pass filter with Caprio technique developed. The architecture of the circuit is quite simple and proportional, symmetrical with signs of difference. Circuits developed into integrated circuits act like basic circuits for frequency filter circuits, current modes with Caprio techniques, obtained by improving the first-order low-pass filter for signal differences with incoming impedances. Adjusting the parameters of the circuit with the caprio technique achieves the optimal parameter value for correcting the total harmonic distortion value.
 The results of testing the operation of the circuit, a fully-balanced current-tunable first-order low-pass filter with Caprio technique developed and designed using the PSpice program. The simulation results showed good results in line with predicted theoretical analysis. The sensitivity of the device to the center frequency (ω0) response is low and independent of variables, the angular frequency is linear with wide current adjustment throughout the sweeping range of a wide frequency range, with a wide range of over tree orders of magnitude. Therefore, fully-balanced current-tunable first-order low-pass filter developed is very suitable to apply various applications regarding low frequency signal filtration, for example in biomedical systems, for example.

A Low Complexity and High Modularity Design for Continuously Variable Bandwidth Digital Filters

ABSTRACT Digital filters with variable bandwidth can be used for a variety of applications. Arbitrary change in the bandwidth of a digital Finite Impulse Response (FIR) filter can be acquired using sampling rate converters. In this paper, a sampling rate converter is proposed which is generated from Pascal structure, a fractional delay filter having low hardware complexity and high modularity. The proposed sampling rate converter requires lesser number of multipliers for implementation when compared with the sampling rate converters in the literature. A low pass filter having a single bandwidth sandwiched between two sampling rate converters can contribute multiple bandwidths in such a way that each bandwidth is an arbitrary variation of the original bandwidth. A two stage Frequency response masking approach (FRM) is used for the hardware efficient design of the original low pass filter. A low complexity and high modularity novel design for a continuously varying bandwidth of a digital FIR filter is proposed in this paper using the proposed sampling rate converter. The modularity of the Pascal structure can be used to control both pass band ripple as well as stop band attenuation of the continuously variable bandwidth FIR filter design. Different communication standards in a Software defined radio (SDR) channelizer is realized using the proposed design of continuously variable bandwidth filter.

An Incremental Quantities Distance Protection Using Park's Transformation

In this article, an incremental quantities distance protection using Park's transformation is proposed to increase the operation speed of distance protection. Based on the instantaneous voltage in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">abc</i> frame approximate linear distribution along the AC transmission lines, this article proves that instantaneous voltage in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dq</i> frame still satisfies the approximate linear distribution along the AC transmission line. Then, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</i> -axis voltage components of fault point and setting point are used to determine the internal and external faults. In order to ensure that the presented distance protection can be applied to all fault types, a virtual three-phase system construction method is also presented. The fault point voltage construction method and low-pass filter design method are also discussed. Finally, a typical AC transmission system is developed in PSCAD/EMTDC to verify the performance of the proposed distance protection under different fault conditions. Simulation results indicate that the proposed incremental quantities distance protection has fast operation speed under internal metallic fault conditions and high security under external fault conditions.

Design and Fabrication of Compact Microstrip Low-pass Filter with Thin Film Technique for Wideband Applications

This paper introduces a compact microstrip low-pass filter (LPF) with a very sharp rejection. The proposed LPF is designed to be used for electronic warfare in defense industry. It has 62 dB/GHz attenuation rate, 10 GHz of stopband width and 48.6 dB of stopband attenuation. Moreover, it also has a wide passband and has a high cut-off frequency (f_c) of 6 GHz. The designed filter has been fabricated using alumina (Al2O3) substrate and titanium-gold (Ti-Au) coating on top of that with thin film technique in a clean room. The experimental measurements of the proposed LPF show great agreement with the simulation results, which validates that the presented filter is convenient to be used for applications up to C-band in electronic warfare systems.

An Active and Reactive Power Controller for Battery Energy Storage System in Microgrids

Battery energy storage systems (BESS) are widely used for renewable energy applications, especially in stabilizing the power system with ancillary services. The objective of this paper is to propose an active and reactive power controller for a BESS in microgrids. The proposed controller can operate the BESS with active and reactive power conditions and realize power smoothing and voltage regulation. The demanded active power flow generated through a low pass filter (LPF) is used to control the power smoothing for microgrids. LPF design is presented based on the BESS sizing and genetic algorithm (GA). The demanded reactive power flow generated according to the reactive current calculation is used to compensate the microgrid voltage to fulfill the voltage regulation. The analysis of the vector diagram is adopted to validate the proposed controller and to explain the applicability and functionality of the voltage regulation for microgrids. To verify the validity of the proposed controller, a 1-kW grid-connected inverter is built to demonstrate the ability of power smoothing and voltage regulation. Both simulations and hardware experimental results agree well with the theoretical analysis.

A Microstrip Low-Pass Filter Design Using a Modified Radial Resonator in the Application of Aircraft Distance Measurement Equipment

In this paper, the application of microstrip technology is investigated in low-pass filters. A cascade microstrip low-pass filter with a sharp frequency response and a good cut-off bandwidth is presented using a modified radial resonator. The advantages of this proposed filter include minor losses in the transit band as well as the desired return. This filter design shows consistency when compared with the results of simulation and model performance. A comparison between the parameter values of this filter and previous structures indicates that it is desirable. The proposed filter can be used in modern communication systems such as aircraft distance measurement equipment (DME) antenna.

Design of Low Pass Filter using Passive Inductor

This paper discusses the passive inductor-based low pass filter (LPF) up to 1.144 GHz bandwidth range with the use of integrated passive device (IPD) technology. In this circuit, three MIM capacitors and three inductors are added parallel to create transmission zeros at a frequency of about 2.2 GHz and 3.6 GHz. The filter has been designed by this method with less structure complexity, a small insertion loss, a small chip area, increase bandwidth, and high out-of-band rejection. After the fabrication of the low pass filter circuit, the insertion loss of 0.7 dB, center frequency 600 MHz, and harmonic rejections of 62 dB with the chip area of 1125.21 μm×471.25 μm including pads.

Design of THz low pass filter using split-ring resonators

This paper is about the designing of a passive low pass filter working in the terahertz spectrum constructed from split-ring resonators (SRR) along with raising the level of performance and optimizing the parameters like insertion loss and return loss of the filter. The split-ring resonators have been optimized after a periodic arrangement running parallelly along the center of finite conductor microstrip line. The final filter was designed after testing various SRR array structures. The computed outcome of the filter shows a cut-off frequency at fc = 6.4 THz. The filter shows a satisfactory bandwidth with a low insertion loss. The structure is created using copper of thickness t = 0.035 µm as the microstrip as well as the ground. The substrate used is polyimide with a relative dielectric constant εr = 3.5, loss tangent (tan δ = 0.0027) with a height h = 1.6 µm. The entire dimension on which the filter resides is an area of 35.48 × 21.15 µm2. CST-Design Environment was used to design the schematics and the to plot the response of the filter. The originality of this work is on enhancing a passive LPF by individually adding a unit cell of SRR to the filter.

Design and Fabrication of a Lowpass Filter Using a New Butterfly-Shaped Defected Ground Structure

In this paper, a new Defected Ground Structure (DGS) is introduced and analyzed. The effect of the structure’s dimensions on the location of the attenuation pole and the cutoff frequency to study the frequency characteristics is investigated. In the following, a lowpass filter with 3 dB cutoff frequency at 3 GHz is designed and optimized using the proposed defected ground structure, and its frequency characteristic is reported. The designed lowpass filter is fabricated to verify the simulation process. Also, simulation results, the equivalent circuit, and the measured results with the Network Analyzer are compared.

Design of compact LC lowpass filters based on coaxial through-silicon vias array

By utilizing coaxial through-silicon via (TSV) technology, compact LC low-pass filters (LPFs) are proposed. Firstly, several capacitors based on coaxial TSV are investigated, in detail, by means of analytic calculation, finite element method (FEM) simulation, and measurement. Secondly, a formula for the inductance of coaxial TSV-based spiral inductors is proposed and verified by FEM simulations and measurements. Finally, based on the investigation of TSV-based capacitors and inductors, an analytical model of the proposed LC LPFs based on 2 ×4,2×5,2× 6, and 2 × 7 coaxial TSV arrays is proposed, and the equivalent circuit model and the finite element method (FEM) model are established in ADS and HFSS, respectively. The LPFs are fabricated and verified through measurements. In the proposed LPFs, coaxial TSVs are used as capacitors and inductors simultaneously, which leads to a more compact size. The parasitic capacitance of the inductors can, helpfully, induce a notch point for the proposed LPFs in stopband and improve the roll-off rate.

Research on weak signal detection of integral average digital lock-in amplifier

In the process of detecting the amplitude and phase of the weak signal based on digital lock-in amplifier (DLIA), a low-pass filter (LPF) with an extremely low cut-off frequency is required. Even so, the effect is often not good. The detection results of amplitude and phase of weak signal are distorted and fluctuate sharply. To eliminate the difficulty of LPF design, and to reduce the distortion and output fluctuation of detection results of DLIA, this paper proposes a weak signal detection method based on integral average digital lock-in amplifier (IADLIA), which can be used for weak signal detection under strong noise. This method optimizes the structure of the traditional DLIA based on the principle of cross-correlation detection. And then this paper analyzes the influence of the cut-off frequency and signal-to-noise ratio of the LPF on the detection accuracy and output stability of the weak signal amplitude and phase. Finally, the corresponding weak-signal amplitude at the bearing rotating frequency is accurately detected by the proposed method, and the accurate identification of bearing faults is realized. The experimental results show that the IADLIA is characterized by stable output, strong anti-interference ability and high output accuracy. The proposed method can accurately detect the amplitude and phase information of the weak signal in a strong noise environment, get rid of the structure of LPF, and the overall performance is better than the traditional DLIA.

The Investigation onL1Adaptive Control of the Tilt-Rotor Aircraft

Considering the uncertainty of the flight dynamics model of the tilt-rotor aircraft in different flight modes, anL1adaptive controller for full flight modes control system of tilt-rotor aircraft is designed. Taking advantage of the separation of robustness and adaptive design of theL1adaptive controller, adaptive gain, and low-pass filter are designed to achieve the desired control performance and meet the requirements of flight quality. The simulations of XV-15 tilt-rotor aircraft in helicopter mode and airplane mode are carried out. Then, the simulation of conversion mode is further carried out. The results show that the tilt-rotor aircraft can track the reference signal well under theL1control system. In addition, the changes of states as well as controls in conversion mode flight are quite smooth which is very meaningful for engineering application.

Design of low pass filter with ultra-wide stopband based on DGS and SIRs

This paper presents a novel compact design of a low pass filter (LPF) with a vast rejection band, low insertion loss (IL), and sharp roll-off. The prospective LPF is fed using a modified E-shape microstrip line to improve the higher frequencies rejection band. Two ring slots are engraved in the ground plane and linked to the feeding line through metallic via to provide further improvement in the rejection band. Three coupled stepped impedance resonators (SIRs) are jointed between the I/O ports to improve the filter roll-off. The proposed LPF provides cutoff frequency at 2.8 GHz, and stopband ranges from 3.2 to 20 GHz with an attenuation level less than −20 dB. The lumped RLC circuit model of the proposed LPF is introduced and confirmed by simulation and theory using Keysight Advanced Design System (ADS). This LPF is designed and fabricated on Rogers RT3006 with compact size 13 mm × 8.2 mm. The measurements of the proposed LPF are in good agreement with the simulated results.

Filter Design for A Fractional N-PLL Frequency Synthesizer At 2.4 GHz

Radio frequency transmitter and receivers usually needs an efficient frequency synthesizer, and this synthesizer must use a digital electronic circuit to perform different modern digital application which contain a frequency synthesizer circuit as a main part of the circuits. The fractional-N phase locked loop (PLL) has been used widely in the last twenty year ago because it gives a large bandwidth with fine frequency resolution for various electronic applications. This research presents the design of second order low pass filter at a frequency bandwidth of (50,75,125,250,500) kHz and for each value of the phase margin (30,35,40,47,57,65,70,80) degree, the component values of the filters which the capacitors and resistance were found at each values of the frequency bandwidth and for each phase margin, also the filter impedance, open loop and closed loop gain was calculated, it is found that by proper design of the second order low pass filter component, the system can have more stability operation and the spurs noise in the output can be reduced efficiently.

A Design of Lowpass Filter with High Suppression in Stopband

Beeline compact microstrip resonance cell (BCMRC) is improved to reduce return loss. A lowpass filter in terahertz band is formed by two improved BCMRC cells and a central microstrip, which make the two cells incorporate into one structure successfully. The filter has widened stopband and high suppression characteristic under the same filter’s order. The optimized result is proposed with an insertion loss of less than 0.4dB in the lowpass band from 0 to 100GHz. The stopband with attenuation more than -20dB is from 140GHz to 350GHz, and the stopband with attenuation more than 40dB is from 158GHz to 312GHz. The size of the low-pass filter is 0.8mm×0.4mm, and this filter can be used in mixer or other devices of terahertz.

Low pass filter design with improved stop‐band suppression and synthesis with transformer‐free ladders

Low pass filter design with improved stop‐band suppression and synthesis with transformer‐free ladders

Design and simulation of fourth order low-pass Gm-C filter with novel auto-tuning circuit in 90 nm CMOS

A tunable high-frequency operational transconductance amplifier (OTA) is presented along with its application in the implementation of a Gm-C filter. The OTA is tuned by varying the negative resistance produced by a positive feedback at the output. Post-layout simulation results (using TSMC 90 nm CMOS technology and a 1-V supply voltage) show that the differential DC gain, common-mode gain and OTA unity gain frequency are 34 dB, −26 dB and 10 GHz, respectively. Moreover, for precise control of filter performance, an auto-tuning circuit is presented to adjust the filter cutoff frequency at low power consumption (i.e., 0.6 mW, about 16.3% of the total circuit power consumption). The filter has a cutoff frequency of 1 GHz with a group delay variation less than 6% up to 1.3 fc. The size of filter is 0.040 × 0.023mm2 and the third order intermodulation (IM3) value at cutoff frequency is −37 dB. The Monte Carlo simulation results are presented for predicting the manufacturing process errors.

Design and fabrication of a microstrip lowpass filter with wide tuning range as harmonic suppression with application in Wilkinson power divider

In this article, a tunable lowpass filter (LPF) with a hexagonal stepped impedance resonator and multi open stubs is designed. The − 3 dB cut-off frequency for the proposed LPF is 2.2 GHz. Insertion loss (IL) and return loss (RL) in the passband zone are 0.3 dB and 15 dB, respectively. The frequency response slope (roll-off rate) for the proposed LPF is very sharp and equal to 142.4 dB/GHz. The tuning range of − 3 dB cut-off frequency for the presented LPF is very wide and equal to 2.7 GHz [from 0.5 to 3.2 GHz (84.3%)]. To achieve the desired structure and harmonics suppression, a conventional power divider was designed initially, then the transmission lines (with length of λ/4) were replaced with two LPFs. The isolation, IL, and input RL for the proposed modified Wilkinson power divider are better than 20.1 dB, 3.1 dB and 21.2 dB, respectively, at operating frequency of 1.8 GHz (GSM band). The proposed modified Wilkinson power divider eliminates the 2nd–11th harmonics with high levels of attenuation. The feature selective validation method depicts that the simulation and measurement results for the proposed LPF are in good agreement with each other.

Design of Compact Planar Lowpass Filters by Using Fragment-Type Structure With Multi-Bit Scheme

A novel design method for compact planar lowpass filter (LPF) with prominent roll-off rate and wide stopband suppression is proposed by using fragment-type structures (FTS) with multi-bit scheme. The proposed multi-bit FTS design has the potential to achieve higher LPF performance at higher optimization efficiency, without any prerequisite knowledge about the pivotal LPF structures needed in conventional LPF designs. The definition of multi-bit FTS and the implementation of LPF design with multi-bit FTS scheme are presented in detail. Compared to the LPF design with 1-bit FTS, the 2-bit FTS design may use smaller decision space, take fewer iterations in multi-objective optimization searching, and yet achieve sharper roll-off rate, higher stopband suppression and a wider stopband. For demonstration, planar LPFs on PCB using the 1-bit FTS and 2-bit FTS are designed and tested. The 2-bit FTS design yields a sharp roll-off rate of 123.3 dB/GHz, a relative stopband bandwidth of 165% referred to stopband suppression of 20 dB, and a high figure-of-merit of 21060. Effects of the geometry parameters of the 2-bit elements are further discussed to give some guide rule on using the 2-bit FTS design.