Order Chebyshev Low Pass Filter Research Articles

Coaxial Low-Pass Filter Design and Manufacture

In this study, a low-pass filter with coaxial transmission lines is designed and produced. The objective for designing a coaxial low-pass filter was to utilize both low loss transmission and high breakdown voltage capability for high power microwave applications to enable the suppression of the second harmonic of the 4.4-6 GHz C-Band ( C-Band was selected as a proof of concept ) signals with minimal insertion loss. Microwave and 3D electromagnetic simulators were used in the filter design. The design was started by establishing an 11 th order Chebyshev low-pass filter prototype giving 0.05 dB ripple. Based on this prototype, a filter circuit consisting of capacitors and inductors as lumped elements was designed. The low and high impedances to be selected for the stepped impedance method, which is the basis of the transition to coaxial transmission lines, were decided and the most suitable impedances for manufacturing was determined. The filter using these impedances and designed with stepped impedance lines was transformed into the filter in which coaxial transmission lines are used. Coaxial transmission lines in the low-pass filter circuit consist of conductors with an insulating material in between. While the insulating material is selected as air in the high impedance sections of the transmission lines, it is PTFE (Polytetrafluoroethylene) with an insulating constant of 2.1 in the low impedance sections. The designed filter was manufactured. The basic properties of the manufactured filter were characterized by using RF measuring devices and compared with the designed filter. The measurements results prove that the frequency responses of the designed filter and the produced filter are very close to each other. Namely, a low-pass filter with a cutoff frequency of 6 GHz, a sharp suppression of about 45 dB at the stopband of 9 GHz and a return loss of 20 dB was designed and produced by using coaxial transmission lines. The novelty in our work can be stated that the power handling capability is increased by two techniques. The first one is that the highest transmission line radius preventing the higher order mode excitations is used to decrease the conductor loss. Teflon is covered around the low impedance lines to enhance the dielectric breakdown capability. Teflon inclusion is also used to decrease the practical low impedance level that improves the filter characteristics.

Design and optimization of microstrip filtering antenna with modified shaped slots and SIR filter to improve the impedance bandwidth

This paper presents a new compact microstrip filtering antenna with modified shaped slots to improve the impedance bandwidth. The proposed microstrip filtering antenna consists of three parts; the monopole radiating patch antenna, the SIR filter, and the feeding microstrip line. The design structure is achieved on one sided glass epoxy FR-4 substrate with dielectric constant e_r = 4.4 and thickness of h = 1.6 mm. The design procedures of the proposed filtering antenna starts from the second order Chebyshev low pass filter prototype. The simulation results throughout this article are done by a computer simulation technology (CST) software. The simulated results have been achieved show good performance of S11-parameter and broad side antenna gain on +z-direction. This design has two transmission zeros at 5.4 GHz and 7.7 GHz, and bandwidth (B.W) of about 1.66 GHz so; it is suitable for high speed data communication. This design has good skirt selectivity.

Fractional Order Capacitor in First-Order and Second-Order Filter

Background: Fractional order Butterworth and Chebyshev (low-pass filter circuits, highpass filter circuits and band-pass filters circuits) types of first and second order filter circuits have been simulated and their transfer function are derived. The effect of change of the fractional order α on the behavior of the circuits is investigated. Objective: This paper presents the use of fractional order capacitor in active filters. The expressions for the magnitude, phase, the quality factor, the right-phase frequencies, and the half power frequencies are derived and compared with their previous counterpart. Methods: The circuits have been simulated using Orcad as well as MATLAB for the different value of α. We have developed the fractional gain and phase equations for low pass filter circuits, high pass filter circuits and band pass filter circuits in Sallen-Key topology. Results: It is observed that the bandwidth increases significantly with fractional order other than unity for the low pass as well as high pass and band pass filters. Conclusion: We have also seen that in the frequency domain, the magnitude and phase plots in the stop band change nearly linearly with the fractional order. If we compare the fractional Butterworth filters for low-pass and high-pass type with conventional filters then we find that the roll-off rate is equal to the next higher order filter.

Area and power efficient flipped voltage follower based symmetrical floating impedance scaler with improved accuracy for fully differential filters

A Source Follower based Symmetrical Floating Impedance Scaler (SF-SFIS) circuits are reported in the prior works, which realize large capacitors with the low area for a fully differential filter. In this paper, a novel Flipped Voltage Follower based Symmetrical Floating Impedance Scaler (FVF-SFIS) with high accuracy is presented. The proposed circuit based on flipped voltage follower with cascaded current mirrors can detect low base capacitors which have lower area and power than the prior SF-SFIS circuits. In order to evaluate its performance and comparison, a 500 pF capacitor is realized by multiplying the base capacitor of 10 pF using both FVF-SFIS and SF-SFIS methods. The magnitude and phase of these impedance scalers are obtained through post-layout simulation. It is found that the proposed impedance scaler requires 51.58% lower area, 69.23% lower power dissipation, and 91.33% higher accuracy than the SF-SFIS. The accuracy of the proposed FVF-SFIS is compared with SF-SFIS circuit by designing a 3rd order Chebyshev low pass filter (LPF) using FVF-SFIS and SF-SFIS with cut-off frequency 100 Hz. The circuit has been designed and simulated in UMC 180 nm technology.

Digital All-Pass Filter Modeling Based on Desired Group Delay Using Advanced Material: A Review on the Signal Processing Part

This paper presents a review on three types of techniques in designing digital all-pass filters based on group delay. All the three methods use the same basic concept rooting back to the requirement of a stable transfer function of the filter which should be a minimum-phase type, and the denominator group delay. The most optimized of the three is chosen to be implemented in MATLAB in order to decrease the group delay variation of a 5th order Chebyshev low-pass filter with cut-off frequency of 160 MHz. The digital transfer function of the low-pass filter is obtained from the analog transfer function by means of bilinear transformation. The sampling frequency of the digital LPF is 100 times the cut-off ffrequency to retain the response of the analog LPF. Both of the filters are then cascaded together and the overall group delays variations are analyzed. The variations of group delay shows a reduction but the price paid is the increase of the overall group delay of the system.

Approximated Fractional Order Chebyshev Lowpass Filters

We propose the use of nonlinear least squares optimization to approximate the passband ripple characteristics of traditional Chebyshev lowpass filters with fractional order steps in the stopband. MATLAB simulations of(1+α),(2+α), and(3+α)order lowpass filters with fractional steps fromα = 0.1 toα = 0.9 are given as examples. SPICE simulations of 1.2, 1.5, and 1.8 order lowpass filters using approximated fractional order capacitors in a Tow-Thomas biquad circuit validate the implementation of these filter circuits.

Fault Detection of Analog Circuits Using Network Parameters

A new method to detect component faults in analog circuits is proposed in this paper. Network parameters like driving point impedance, transfer impedance, voltage gain and current gain are used to detect component faults in analog circuits as these network parameters are sensitive to the components of the circuit. Using montecarlo simulation each component of the circuit is varied within its tolerance limit and the minimum and the maximum values of each network parameter are found for fault free circuit. At the time of testing, the network parameters are found for the injected fault and if any one or more network parameters is exceeding its predetermined bound limits then the circuit is confirmed faulty. The proposed method is validated through second order Sallenkey band pass filter and fourth order Chebyshev low pass filter circuits. Numerical results are presented to clarify the proposed method and prove its efficiency.

A Low Power, Fully Differential Bulk Driven OTA in 180 nm CMOS Technology

A low voltage, low power bulk driven Operational Transconductance Amplifier (OTA) with feed-forward compensation is presented. The OTA is designed in 180 nm technology and achieves an open loop DC gain of 44.05 dB, 3 dB bandwidth of 408 kHz and Unity Gain Bandwidth (UGB) of 9.07 MHz. OTA is stable with phase margin of 45o and a gain margin of 66 dB for a pure capacitive load of 1 pF. OTA operates on 0.5 V supply consuming a power of 30 µW. As an application, a fifth order Chebyshev low pass filter is designed for a bandwidth of 480 kHz. Filter follows the ideal response up to an attenuation of 50 dB.

Test Mismatch in Switched-Current Circuits Using Wavelet Analysis

Errors of mismatch and currents calibration caused by channel geometrical variety in switched-current are investigated in this paper. The relation and computing of mismatch and sensitivity are discussed also, and then a measure method of switched current mismatch using wavelet decomposition is proposed. A selected group of same transconductance is choosing as a cohort firstly, and the sensitivities of cohort in relation to the variation of transconductance are computed. Compared with the nominal deviation and tolerance borderline, the optimization and testing can be performed. As an example, a sixth order chebyshev low-pass filter is simulated and tested. The results have justified the reliability and feasibility of the method.

Vision for humanity

A Source Follower based Symmetrical Floating Impedance Scaler (SF-SFIS) circuits are reported in the prior works, which realize large capacitors with the low area for a fully differential filter. In this paper, a novel Flipped Voltage Follower based Symmetrical Floating Impedance Scaler (FVF-SFIS) with high accuracy is presented. The proposed circuit based on flipped voltage follower with cascaded current mirrors can detect low base capacitors which have lower area and power than the prior SF-SFIS circuits. In order to evaluate its performance and comparison, a 500 pF capacitor is realized by multiplying the base capacitor of 10 pF using both FVF-SFIS and SF-SFIS methods. The magnitude and phase of these impedance scalers are obtained through post-layout simulation. It is found that the proposed impedance scaler requires 51.58% lower area, 69.23% lower power dissipation, and 91.33% higher accuracy than the SF-SFIS. The accuracy of the proposed FVF-SFIS is compared with SF-SFIS circuit by designing a 3rd order Chebyshev low pass filter (LPF) using FVF-SFIS and SF-SFIS with cut-off frequency 100 Hz. The circuit has been designed and simulated in UMC 180 nm technology.