Figure 4 represents a Dataforth SCM generic 7-pole LP filter frequency and unit step response. Dataforth designers are professionals with decades of experience in filter design. They balance the attributes of selected poles in multi-pole filter topologies to provide near ideal lowpassfilterbehavior. Moreover, Dataforth realizes that industrial data acquisition and control systems must have premium high quality filters for noise suppression and aliasing prevention. Figure 4 visually illustrates some outstanding attributes of quality multi-pole lowpass filtering that Dataforth designs in all their SCMs. These are the qualities necessary for premium lowpass filtering in SCMs. Readers are encouraged to visit Dataforth’s website and examine Dataforth’s complete line of SCM filter attributes
A filter can be used to select different frequencies of a signal. A filter is called low-pass if its frequency response is located around zero, and is high-pass if it is around 𝜋. In filters, the frequency response is unity for a certain range of frequencies and is zero for the remaining frequencies. Because of the inherent periodically of the discrete time frequency response, it is similar to a multi band filter, since frequencies around 2𝜋 are indistinguishable from frequencies around 0. The frequency response passes only low frequencies and rejects high frequencies of the signal. Since the frequency response of the signal is completely specified by its behavior over the range , the ideal low-passfilter frequency response is more typically shown only in range . It is understood that the frequency response repeats with period of 2𝜋 outside the plotted range.
However, atomic levels are not stable and have only a finite lifetime when they interact with the electromagnetic field, except the ground state. All the theories developed can not satisfactorily describe behavior of unstable atoms, since Schrödinger equation are dealing with stable atomic states ⁄ = 0.. The electron of the atom is not only subjected to the external light field but to other perturbations also. For instance in a gas, the atom can collide with other atoms all the time. In a solid the electron can interact with lattice vibrations, etc. The state can not be considered stable ⁄ ≠ 0. Reviewing the work done by Mandel , Haken , Allen and Eberly , we modified Maxwell- Bloch equation above with addition of atomic decay process. Thus equation (21) becomes
A new active lowpassfilter comprising of two general purpose operational amplifiers (OAs), four resistors and one capacitor is presented. The analytical expressions are obtained and the performance of the proposed circuit is examined in relation to the conventional circuit. Simulation and experimental results are presented which establish the superiority of the proposed lowpassfilter on the conventional circuit.
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To build an RF MEMS structure with micromachining, the wafer could be processed using conventional processes to create transmission line capacitors and inductors that are required before the RF MEMS processing starts. A resist layer is then deposited and patterned to protect this part of the circuit from the RF MEMS processing steps. This layer can be removed at the completion of RF MEMS fabrication. The surface micromachining involves the selective adding and removing of metal, dielectric and sacrificial layers on the substrate surface. Depending on the step, either a metal or a dielectric or a sacrificial layer is then deposited, patterned and etched. This sequence of steps is repeated until the required RFMEMS three-dimensional structure is completed. The process employs four masks for device fabrication and one additional mask for the fabrication of package structure. Four inches quartz wafers are used for the device fabrication. The package structures are patterned in the form of rings of SU8-10 on standard silicon substrate. The released structures of tunable lowpass filters are subjected to wafer level packaging using chip on wafer bonding with the help of Fine Tech Fine Placer Flip Chip Bonding. Further, the effects of introducing thick metal for DC actuation in the ground plane (Type A in Figure 1) and thin metal for DC actuation (Type B in Figure 1) are studied.
Baseline noise typically corrupts EKG signal due to patient’s respiration, motion of patient’s body, and electrodes. This noise could mask some important features. Therefore, it is extremely important to remove this noise. Equiripple highpass filter is capable of removing this noise completely without affecting the other important features of the signal. Equiripple highpass filter allows the main components of EKG signal to pass on such as P, QRS complex, and T waves as well as PR segment, PR interval, ST segment and QT interval. All mentioned intervals and segments correspond to certain frequencies. Hence, maintaining important frequencies are crucial. Based on American health association, the smallest component frequency is 0.05 Hz. Nonetheless, in practical, the baseline noise has frequency extend to the value of 1Hz. This means there is some feature that is distorted due to using highpass filter . Nevertheless, the ST segment is not the area of interest in this paper. In fact, among the advantages that Equiripple filter has is the narrow band width that can be built and this feature can be maintained. However, building narrow transition band width that would maintain the ST segment using Equiripple requires filter with high order exceeds 5000. This order prevents us from using the zero phase filter built in as a function in Matlab to eliminate the time delay introduced by high passfilter which is crucial to preserve important feature. As a matter of fact, Matlab does not recognize zero or negative indices value that might be introduced due to time delay. This built-in function (filtfilt) requires the signal length to be more than three times of filter order. The Equiripple highpass filter used has a filter order of 2746, cutoff prequency at 1 Hz, stop frequency at 2 Hz, and stop attenuation of 80 dB. Figure 5,6,7 shows the original EKG signal, FFT of the signal, and EKG after removing baseline nose from the signal. It is so obvious that the baseline noise is completely removed while all features are preserved. After this stage, the DC offset due to baseline noise is successfully and completely removed.
A number of current and voltage mode all-pass filters employing the DDCC have been suggested . How- ever most of these realizations employ floating capacitors and resistors which require a large area to be imple- mented by MOS transistors. The proposed structure use two DDCC, two CCII and only grounded capacitor. The input of the voltage-mode (VM) all-passfilter is con- nected to the Y terminal (high input impedance) and its output is connected to the X terminal (low output im- pedance). For this reason the proposed structure doesn’t necessitate a buffer cascade with another bloc. The ar- chitecture of the filter is given in Figure 1.
Sigma Delta converter have received much attention in recent years in VLSI industry, due to technological advancement. A general figure of sigma-delta (Σ-Δ) modulator is shown in fig.1. The sigma-delta (Σ-Δ) ADC is the converter used in recent voice- band, audio, and high-resolution precision industrial measurement applications. Due to implicit anti-aliasing filter, Continuous time sigma-delta (Σ-Δ) modulators are the best solution for digital front ends, and 90% of die is implemented in digital circuitry which enhances the vision of CMOS technology. In present scenario of CMOS processes the highly digital architecture is suited, thereby allowing easy addition of digital functionality without significantly increasing the cost.
ABSTRACT: In this paper, design of sub-circuits of switched capacitor filter using 0.18µm CMOS technology. The basic building blocks of switched capacitor filters are sample-and-hold circuit, non-overlapping clock and a gain stage. The fully integrated designs of a lowpassfilter having cut-off frequency of 150Hz and a high passfilter having cut-off frequency of 0.05Hz using switched capacitor circuits are presented. This combination of a lowpassfilter and a high passfilter results in a band passfilter which have the bandwidth of 0.05Hz to 150Hz, which is ideal in detecting ECG signals. The filters are made with the help of op-amps whose gain is 47.119 dB.
the pole frequency of 3.36 MHz and Q = 0.65, while calculated value of pole frequency from (7) is 3.38 MHz (deviated by 0.59 %). The results shown in Fig. 4 are the gain and phase responses of the proposed filter obtained from Fig. 2. It is clearly seen that the proposed filter can provide low-pass, high-pass, band-pass, band-reject and all-pass functions, dependent on digital selection as shown in Tab. 1, without modifying circuit topology. Fig. 5 and Fig. 6 display gain responses of band-pass function for different I B2 and I B3 values. It is shown that the quality
VAC’s current product spectrum for the ADSL/VDSL system fulfils the market demands and the customers needs. Besides the established filter components, splitters CPE and splittercards CO for ADSL/VDSL, VAC also produces for ADSL/VDSL the new lowpassfilter LCR modules. Besides the LCR Modules designed according the international ITU-T and ETSI ATA standards, VAC also develops customized LCR modules with additional requirements. Development work is based on a close cooperation between the customer and VAC and on the specifications of the customer. Afterwards the modules are manufactured by VAC in process and cost optimized plants. Our in-depth knowledge of the application fields and technical requirements puts us in a position to find the ideal solution and turns this into an innovative product. The VAC ADSL/VDSL LCR modules are developed with a maximum reduction of PCB space, including all components for a splitter and no need for additional capacitors or resistors. They were all delivered with a fully tested filter performance.
An active filter is a network of passive R, C elements, and one or more active elements. The active element is usually one or more op-amps. Active filters offer accuracy, stable tuning, and high immunity to electromagnetic interference. The high input and low output impedance found in active filters allow combinations of two or more stages without the interaction found in passive cascades. Active filters function similar to simple, frequency-selective control systems; as such, any desired filter characteristic can be generated from the interconnection of integrators, inverter, summing amplifier, and integrators.
Gaussian filter is a class of lowpass filter based on the Gaussian probability distribution function used to blur images and remove noise and preserve the details. Gaussian Low-pass filtering has been used in previous researches for removing the speckle noise in ultrasound images. Gaussian filter has similar function as median filter but it uses different kernel, which has the bell-shaped distribution. Gaussian filter modifies the input by convolution with a Gaussian function. The transfer function of Gaussian lowpassfilter is given by,
by several authors in performing a non-ideal analysis of their propositions but to the best of the knowledge of the authors, any explicit use of OTRA-pole in evolving external capacitor-less, active-R circuits using OTRAs has not been reported so far. The main purpose of this paper is, therefore, to report three OTRA-based active-R circuits which realize an inductor, an oscillator and a low-pas/band-passfilter respectively in which the pole of the OTRA has been exploited advantageously to result in circuits which have the interesting feature of employ- ing a low number of total components. The workability of the proposed circuits has been demonstrated by SPICE simulation results based upon CMOS-OTRA implementation using 0.5 µm CMOS technology.
The impulse response of the designed FIR filter is always stable but it requires a large memory space to store the filter coefficients due to the high order. The number of filter coefficients can be lessened if the required specifications are implemented with an IIR filter. However, it can be unstable because of the recursive calculations. Table III shows the design specifications for band-stop IIR filter to remove 60 Hz noise and Fig. 12
Abstract- Low Power Consumption is the main target in today’s Technological aura and as Very large scale integrated circuit (VLSI) designing is very complex and it require much conceding nature to realise application precise objective. With increasing the efforts to reduce Power Consumption and to reduce W/L ratio, Lowpass and high passfilter structure have widespread application and using CMOS Operational Trans-conductance amplifier gives capability to perform well in Nano-meter range as it has better control over short channel effect and other scaling problem like gate leakage, sub-threshold conduction. Lowpass and high passfilter based on OTA for VHF and UHF frequency applications. At high frequencies, the OP AMP based active filters has limited performance. We cannot change the values of resistors and inductors but OTA-C filter provides ability to change their values by changing trans-conductance of OTA. The proposed filter consists of OTA and capacitors. This filter shows low sensitivity to passive components, low component count and ease in design. The simulations are done using Tanner EDA version 16.2 at 0.25nm technology.
From Table III we can conclude that the CMOS based OTA reduces the static power dissipations drastically & also the pass band gain is nearer to 0dB i.e. unity gain which is our objective. It may be further noted that the bias voltage for CMOS OTA is reduced greatly. We call our proposed OTA based LPF as tunable because by adjusting the values of power supply and sink current we can get different pass band gain less than unity. Again, the high cut-off frequency can be adjusted by changing simply the values of resistor, R and capacitor, C of the input RC section. The other advantages of our design over conventional OPAMP based LPF are (1) a single power supply is required, (2) CMRR, PSRR, slew rate are better. (3) noise margin is high, (4) design is very simple, (5) fabrication cost is reduced greatly.
An alternative approach, proposed by Watanabe  and Matsui , , is to determine the speed from the ratio of the amplitude of the induced electromotive force (EMF) to the excitation flux linkage. However, while this method of speed estimation has a fast response, it has two significant drawbacks. Firstly, the calculation of the EMF requires the differential of the current. Thus, noise can cause a potentially significant speed error. While Sharkh ,  eliminated the need for the differential, this resulted in a significantly more complex control system design. Kim , on the other hand, assumed that the current was constant at the end of each flux observing step, so that its differential was zero. However, in general, such an assumption is not appropriate. Secondly, parameters, such as the winding resistance, inductance, and excitation flux linkage, may vary, due, for example, to variations in temperature and saturation, and cause further errors in the estimated speed. Thus, Kim  also compensated for parameter variations, using the estimated average speed as the compensation refer- ence (i.e., input variable). However, it is difficult to compensate for variations in three parameters from only one input variable. In general, the derivation of the speed from the estimated rotor position results in significant noise. Further, while the estima- tion of the average speed may be accurate under steady-state operating conditions, it is usually not fast enough to give good dynamic response. In contrast, the estimation of the speed from the induced EMF and excitation flux linkage results in fast dy- namic response but low accuracy. Therefore, the development of an improved speed estimation method is of considerable in- terest.
The communication industry field is mainly focused by high data transfer and more channel capacity in mobile communication. VLSI technology is used to modify any type digital based hardware architecture and to reduce the hardware system power, speed and complexity level. The filter process is mainly used to DSP and DIP real world application. The filter process is to remove the noise in original signal or image. So the filter architecture optimized process, to reduce the filter processing time and to increase the performance. Adaptive digital filters find wide application in several digital signal processing (DSP) areas. FIR filter architecture is used to effectively remove the noise in received channel data bits and to require less circuit complexity.The existing system frequency transformation based filters (FT filters) provide an absolute control over the cutoff frequency. However, the cutoff frequency range of the FT filters is limited. The second-order frequency transformations combined with coefficient decimation technique based filter (FTCDM filter) has wider range compared with the FT filter. But this method have some limitation. So we use the discrete cosine transform (DCT) modulation based lowpassfilter transformation process. Proposed system is to design a 18-band DCT transform signal denoising architecture simulink design. This simulink design is to consist the XILINX based digital architecture block. Discrete cosine transform (DCT) modulation are utilized to generate a uniform 18-band filter bank first, and then all elements of are replaced by all-pass filters to obtain a non-uniform filter bank. A fast recursive structure and variable-length algorithm is further developed to efficiently accomplish DCT modulation. Proposed system is to improve the output signal reconstruction effectively. Proposed system is to reduce the latency level and to increase the application system speed level.