Butterworth filter

About: Butterworth filter is a research topic. Over the lifetime, 6187 publications have been published within this topic receiving 69070 citations.

Filter structures composed of all-pass and FIR filters for interpolation and decimation by a factor of two

Abstract: This paper introduces filter structures for interpolation and decimation by a factor of two. The structures are derived by using the frequency-response masking approach, in which the overall filter makes use of a periodic model filter, its complementary filter, and two masking filters. The periodic model filters are obtained by replacing each delay element in a model filter with M delay elements in cascade. The model filter is a half-band infinite-impulse response (IIR) filter composed of two all-pass filters in parallel, whereas the masking filters are linear-phase finite-impulse response (FIR) filters. In the final interpolator and decimator structures the filtering takes plate at the lowest of the two sampling rates involved. The corresponding overall filter can be designed by separately optimizing a half-band IIR filter and a linear-phase FIR filter. Both nonlinear-phase and approximately linear-phase filters are considered. One advantage of the proposed filter structures over conventional half-band IIR filter structures is that their maximal sample frequency is M times higher, which may be utilized to increase the speed in an implementation and/or to reduce the power consumption via power supply voltage scaling techniques. In the case of approximately linear-phase filters, the computational complexity can be reduced as well. Several design examples are included demonstrating the properties and advantages of the proposed filter structures.

Modified linear phase frequency response masking FIR filter

Abstract: This paper proposes a modified frequency response masking (FRM) technique for the synthesis of linear phase, sharp transition, low arithmetic complexity FlR filter. The structure is composed of lowpass and bandpass subfilters which are designed as linear phase, equiripple passband and computationally efficient FIR filters. The frequency response of the subfilters are modeled using trigonometric functions of frequency and the design yields closed form expressions for the impulse response coefficients of the subfilters. The slopes at the edges of the transition region of the subfilter are matched which makes the frequency response a continuous function of frequency and hence reduces the effects due to Gibb's phenomenon thereby reducing passband edge ripple of the subfilters. The bandpass filter eliminates one masking filter and a model filter from the basic FRM approach thereby simplifying the synthesis of the proposed modified FRM FIR filter.

A class of two-channel approximately perfect reconstruction hybrid analog/digital filter banks

Abstract: This paper introduces a class of two-channel hybrid analog and digital filter banks which find application in high-speed A/D conversion. The distortion caused by mismatch errors in time-interleaved A/D converters is attenuated using hybrid filter banks. The proposed class of filter banks satisfy perfect reconstruction within certain tolerances that can be controlled in the filter design. The filter design uses both linear and nonlinear programming.

Segmented transversal filter

Abstract: A segmented digital transversal filter comprising a first transversal filter 4 that eliminates all frequency components from a signal sequence above half the subsampling frequency, a second transversal filter 11 that convolutes the output of the first filter with a decimated and energy compensated lower band of filter coefficients (HI 1 '), a third transversal filter 22 that convolutes the output of the first filter and a decimated and energy-compensated upper band of filter coefficients (HI 2 '), and a fourth transversal filter 32 that convolutes the original signal sequence and the central band of filter coefficients (HI 3 ). Delays 21 and 31 are added so that the outputs of the second, third and fourth filters arrive concurrently at an adder 51, the sum being the output of the invention.

A method for exceptionally low noise single channel recordings.

Abstract: We present a method whereby, with integrating electronics, quartz patch electrodes and a novel use of silicone oil, background noise levels as low as .083 pA RMS in a 5 kHz bandwidth (4-pole Butterworth filter) have been achieved in single channel patch clamp recordings. These approaches result in much higher signal to noise ratios for single channel recording than have previously been reported and should allow many investigators to significantly reduce noise at a constant bandwidth or to increase their recording bandwidths by several kHz.