Topic
Butterworth filter
About: Butterworth filter is a research topic. Over the lifetime, 6187 publications have been published within this topic receiving 69070 citations.
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Papers
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TL;DR: In this article, a method of constructing an acoustic filter incorporating a technique in which the filter is modelled with one or more distributed two port elements is presented, where each distributed element is defined by a characteristic impedance and length and includes a waveguide filter which does not require damping.
Abstract: A method of constructing an acoustic filter incorporates a technique in which the filter is modelled with one or more distributed two port elements. The or each distributed element is defined by a characteristic impedance and length and includes a waveguide filter which does not require damping. The or each filter section is characterized in that it has at least two resonances which are used to shape a specified response for the filter. A substantially reactive acoustic filter constructed according to the method and a loudspeaker system incorporating such an acoustic filter are also disclosed.
22 citations
13 Oct 2011
TL;DR: A simple voltage-mode first-order all-pass (AP) filter implementation is presented which employs only MOS transistors instead of active elements like CCH, CDBA, FTFN, etc. that include large number of transistors.
Abstract: In this study, a simple voltage-mode first-order all-pass (AP) filter implementation is presented which employs only MOS transistors instead of active elements like CCH, CDBA, FTFN, etc. that include large number of transistors. Transconductance (g m ) and gate-to-source parasitic capacitance (C gs ) of the transistors are employed to form the AP transfer function. It is shown that simulations are in good agreement with the theoretical results.
22 citations
Patent•
01 Apr 1981
TL;DR: In this paper, a switchable filter circuit for use in a receiver to select a first or a second frequency band from a received signal and for providing predetermined minimum stop band attenuation at frequencies outside the selected frequency band, the second frequency bands lying wholly within the first.
Abstract: A switchable filter circuit for use in a receiver to select a first or a second frequency band from a received signal and for providing predetermined minimum stop band attenuation at frequencies outside the selected frequency band, the second frequency band lying wholly within the first. A first filter element is provided which defines a primary pass band corresponding to the first frequency band, and a second filter element is provided which defines a secondary pass band corresponding to the second frequency band, the first filter element having an input to which the received signal is applied, and the second filter element have an input for receiving the output of the first filter element. The stop band attenuation of the first filter element is at least as great as the predetermined minimum stop band attenuation required, and the stop band attenuation of the secondary filter element within the primary pass band being that which is required by the application. Thus the first filter element significantly determines the stop band characteristics of the filter circuit as a whole outside the primary pass band.
22 citations
TL;DR: The proposed procedures can be used in direct optimization of OTA-C filters with respect to important characteristics such as noise performance, THD, IM3, DR or SNR as well as a simple optimization procedure using equivalence transformations.
Abstract: Efficient procedures for evaluating nonlinear distortion and noise valid for any OTA-C filter of arbitrary order are developed based on matrix description of a general OTA-C filter model. Since those procedures use OTA macromodels, they allow us to obtain the results significantly faster than transistor-level simulation. On the other hand, the general OTA-C filter model allows us to apply matrix transforms that manipulate (rescale) filter element values and/or change topology without changing its transfer function. Due to this, the proposed procedures can be used in direct optimization of OTA-C filters with respect to important characteristics such as noise performance, THD, IM3, DR or SNR. As an example, a simple optimization procedure using equivalence transformations is discussed. An application example of the proposed approach to optimal block sequencing and gain distribution of 8th order cascade Butterworth filter is given. Accuracy of the theoretical tools has been verified by comparing to transistor-level simulation results and to experimental results. Copyright © 2006 John Wiley & Sons, Ltd.
22 citations
Patent•
15 Oct 2009TL;DR: In this article, a poly-phase filter and a harmonic filter are used to generate in-phase and quadrature output signals of a radio frequency (RF) transceiver.
Abstract: A radio-frequency (RF) apparatus, which may reside in a receiver or transceiver, includes receive-path circuitry. The receive-path circuitry includes a poly-phase filter and a harmonic filter. The poly-phase filter accepts an input signal and generates two output signals. One output signal of the poly-phase filter constitutes an in-phase (I) signal. The other output signal of the poly-phase filter constitutes a quadrature (Q) signal. The a harmonic filter couples to the poly-phase filter. The harmonic filter accepts as input signals the in-phase and quadrature output signals of the poly-phase filter.
22 citations