Showing papers on "Butterworth filter published in 1968"
TL;DR: In this article, the authors present the theory and application of lumped-image parameter reactive filter networks, absorptive type filter networks and combined absorptive-reactive filter networks as conducted electromagnetic interference reduction circuits.
Abstract: This paper presents the theory and application of lumped-image parameter reactive filter networks, absorptive-type filter networks, and combined absorptive-reactive filter networks as conducted electromagnetic interference reduction circuits. A comparison of the passband characteristics by specific examples is given for filter configurations of the pi, T, absorptive, and absorptive-reactive type under implementation conditions of a fixed source impedance and a varying load impedance as encountered when filtering prime power sources feeding ac to dc converters. This paper illustrates the problem the design engineer faces when applying the usual data given in filter catalogs. The filter characteristics are presented for 50-ohm resistive source and load conditions because of MIL-STD-220A quality control testr equirements. A test configuration is recommended to determine the admittance transfer of a filter network, indicative of the networks performance characteristics under application conditions.
11 citations
TL;DR: In this article, the synthesis of a general class of filter with maximally flat passband and Chebyshev stopband attenuation characteristic is presented, where the filter has an nth order voltage transfer function with m pairs of transmission zeros in the stopband, where n \geq 2 m + 1.
Abstract: The synthesis of a general class of filter with maximally flat passband and Chebyshev stopband attenuation characteristic is presented. The filter has an nth order voltage transfer function with m pairs of transmission zeros in the stopband, where n \geq 2 m + 1 . Butterworth and inverse Chebyshev filters are special cases of this general class with m = 0 and n = 2m + 1 , respectively.
9 citations
Patent•
02 May 1968
TL;DR: In this paper, a low pass filter for insertion between two circuits, such as a power supply and a load circuit, that blocks the passage from one circuit to the other of radio frequencies above a given pass band, is presented.
Abstract: A low pass filter for insertion between two circuits, such as a power supply and a load circuit, that blocks the passage from one circuit to the other of radio frequencies above a given pass band, and which continues to function as a satisfactory filter under the condition of reactive components in the power supply and load circuits being close to resonant values with reactive elements in the filter. The filter comprises a pi network having a series line extending between the network input and output ends that includes an inductive circuit element, and shunt lines branching from the series line that include capacitive elements with resistance to establish resistance-capacitance elements that introduce circuit losses which reduce the Q of the shunt lines to inhibit resonances that might otherwise impair the filtering function of the device.
7 citations
TL;DR: In this article, a bilinear transformation is used to obtain a rational transfer characteristic for a continuous filter that satisfies the design specifications, and the sampled-data filter obtained by this design method exhibits the same frequency response characteristics as the continuous filter, except for a nonlinear warping of the frequency scale.
Abstract: The frequency domain of wide-band linear sampleddata filters is considered. The sampled-data filter is termed ?wideband? when the frequency range of useful approximation to its continuous counterpart approaches half the sampling frequency. Sampled-data filter representations for continuous filters can be obtained using several different design procedures.[1] A particular design method utilizing the bilinear transformation is developed. The method is especially useful in designing wide-band sampleddata filters which exhibit relatively flat frequency-magnitude characteristics in successive pass- and stop-bands. Filters of this type are widely used in network simulation and data processing problems.[2] The design method possesses two chief advantages over the standard z transform.[3] The first is that the transformation used is purely algebraic in form. This means it can be applied easily to a continuous filter having a rational transfer characteristic expressed in either polynomial or factored form. The second advantage is the elimination of aliasing[4] errors inherent in the standard z transform. Thus, the sampled-data filter obtained by this design method exhibits the same frequency response characteristics as the continuous filter, except for a nonlinear warping of the frequency scale. Compenation for this warping can be made by a suitable frequency scale modification. Some of the more common filter networks to which the design method can be applied effectively are the Butterworth, Bessel, Chebyshev, and elliptic-filter structures. The design method consists first of obtaining a rational transfer characteristic for a continuous filter that satisfies the design specifications.
4 citations
TL;DR: In this paper, a circuit for filtering the noise from a photomultiplier d.c. output current is described, which is achieved by exploiting the resistance-time characteristic of a photoconductive cell on being plunged into darkness after brief exposure to light.
Abstract: A circuit is described for filtering the noise from a photomultiplier d.c. output current. The filter is of conventional RC low-pass type, but with a time constant which increases linearly with time, giving the filter the characteristic of an integrator. This is accomplished by exploiting the resistance-time characteristic of a photo-conductive cell on being plunged into darkness after brief exposure to light.
1 citations
TL;DR: In this article, the use of a galvanometer filter in a low frequency lock-in amplifier is described, where the center of the passband is at a frequency of 035 Hz.
Abstract: The use of a galvanometer filter in a low frequency lock-in amplifier is described. The centre of the passband is at a frequency of 035 Hz. The apparatus was tested and it was found that the signal-to-noise ratio was improved by a factor of about 5 over a Keithley 148 nanovoltmeter.
TL;DR: In this paper, a switchable filter for medical electronics is presented, which will give an optimum linear phase response together with satisfactory amplitude and transient response using a computed in-line pole distribution.
Abstract: A synthesis is presented which has enabled a practical switchable filter to be realized which will give an optimum linear phase response together with satisfactory amplitude and transient response using a computed in-line pole distribution. Theoretical and practical characteristics are compared for a fourth- and sixth-order filter and the appropriate circuit diagrams are given. The application of this type of filter is discussed with particular reference to the field of medical electronics.