Topic
Butterworth filter
About: Butterworth filter is a research topic. Over the lifetime, 6187 publications have been published within this topic receiving 69070 citations.
Papers published on a yearly basis
Papers
More filters
NEC1
TL;DR: A transconductor capable of providing a wide continuous-tuning-range filter applicable to Bluetooth, W-CDMA, LTE, and IEEE 802.11a/b/g W-LANs without sacrificing power consumption or die area is proposed.
Abstract: We propose a transconductor capable of providing a wide continuous-tuning-range filter applicable to Bluetooth, W-CDMA, LTE, and IEEE 802.11a/b/g W-LANs without sacrificing power consumption or die area. The wide tuning range is achieved without the need for any array configuration, using triode-biased input MOSFETs with transconductance that is widely tunable by means of drain bias adjustment. The transconductor also uses an adaptive DC-blocking circuit that suppresses bias current in a high transconductance mode, which results in minimizing transconductor power consumption.A 4th-order Butterworth low-pass filter using this transconductor, fabricated in a 0.18-μm CMOS process, exhibits a cut-off frequency tuning range of 0.3-12 MHz with a current consumption of 0.6-2.6 mA. The die area is small: 0.125 mm2.
22 citations
Patent•
18 Feb 2002TL;DR: An apparatus and method for tuning a filter withoscillator alignment for applications where the filter tuning signal is generated independently of the local oscillator tuning signal and the tuning range is quite large as discussed by the authors.
Abstract: An apparatus and method for tuning a filter (11) with
oscillator alignment for applications where the filter
tuning signal (19,27) is generated independently of the
local oscillator tuning signal and the tuning range is
large, for example such as terrestrial and cable TV
broadcasting (40 to 860MHz). The filter being adapted to
a filter tuning modulation signal (25) having a first
frequency (F1) and a second frequency (F2). Values of
the output signal (28) are measured, a first value (S1)
at the first frequency, and a second value (S2) at the
second frequency, and a comparison signal (26) is
generated in comparing the first value and the second
value to adjust filter with the tuning control signal in
response to the comparison signal, modulation signal and
an approximate filter tuning signal to provide a desired
signal at the output signal.
22 citations
Patent•
17 Aug 2001TL;DR: In this article, a surface acoustic wave filter includes a longitudinally-coupled resonator-type SAWF having at least two interdigital transducers disposed on a piezoelectric substrate along the propagation direction of a surface wave, and at least one SAW resonator connected between an input terminal and/or an output terminal.
Abstract: A surface acoustic wave filter includes a longitudinally-coupled resonator-type surface acoustic wave filter having at least two interdigital transducers disposed on a piezoelectric substrate along the propagation direction of a surface acoustic wave, and at least one surface acoustic wave resonator connected between an input terminal and/or an output terminal and the longitudinally-coupled resonator-type surface acoustic wave filter. In this surface acoustic wave filter, a pass band is formed by utilizing at least one of the resonant modes of the longitudinally-coupled resonator-type surface acoustic wave filter and the inductance of the surface acoustic wave resonator.
22 citations
Patent•
26 Jun 1982TL;DR: In this article, a filter and demodulation circuit is proposed which, when used in a radio-frequency receiver, produces an increase in the sensitivity of the receiver by dividing the intermediate frequency into at least two parallel channels at the input.
Abstract: A filter and demodulation circuit is proposed which, when used in a radio-frequency receiver, produces an increase in the sensitivity of the receiver. In the filter and demodulation circuit, the intermediate frequency is divided into at least two parallel channels (11, 12) at the input (10). Each channel contains a series circuit comprising a mixing and oscillator circuit (13, 15; 14, 16), a controllable IF filter (17, 18), a demodulator (19, 20) and a high-pass filter (21) or low-pass filter (22). One transmission channel essentially transmits the modulation frequencies of a first frequency range only and the other transmission channel transmits the modulation frequencies of a second frequency range. The AF voltage at the output of each transmission channel re-adjusts the IF filter of this channel and the oscillator circuit of the mixing and oscillator circuit of the other channel.
22 citations
TL;DR: In this paper, the design of linear phase FIR digital filters having symmetric or antisymmetric impulse response is formulated as a constrained minimization problem, where the objective function is a convex combination of two objective functions representing the energy of the error between the frequency response of the designed filter and a scaled version of the ideal filter in both the stop and passbands.
Abstract: The design of linear phase FIR digital filters having symmetric or antisymmetric impulse response is formulated as a constrained minimization problem. The constraints express the maximal flatness of the frequency response at the origin in the case of a low-pass filter or at an arbitrary frequency in the passband in the case of a bandpass filter. The objective function, which is a quadratic form in the filter coefficients, is formed as a convex combination of two objective functions representing the energy of the error between the frequency response of the designed filter and a scaled version of the frequency response of the ideal filter in both the stop and passbands.
22 citations