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Showing papers on "Band-stop filter published in 2000"


Journal ArticleDOI
TL;DR: Thresholds for detecting sinusoidal signals were measured as a function of the spectral width of a notch in a noise masker and filter shapes showed a level dependence that qualitatively resembled the level dependence of filtering on the basilar membrane.
Abstract: Thresholds for detecting sinusoidal signals were measured as a function of the spectral width of a notch in a noise masker. The notch was positioned both symmetrically and asymmetrically around the signal frequency. The noise was designed to create equal excitation per ERB within its passbands (uniformly exciting noise), after allowing for the transfer function of the headphone and the middle ear. For a signal frequency of 250 Hz, the level per ERB ranged from 35 to 80 dB in 15-dB steps. For signal frequencies of 500, 1,000, 2,000, and 4,000 Hz, the level per ERB ranged from 40 to 70 dB per ERB in 15-dB steps. Auditory filter shapes were derived from the data by modeling the auditory filter as the sum of a sharply tuned tip filter and a broader tail filter. The gain of the tip filter was assumed to be a function of level. The shape of the tip filter and the gain and shape of the tail filter were assumed to be level independent. The data for all levels were fitted simultaneously. The data were fitted best when the gain of the tip filter was assumed to be a function of the signal level (as opposed to the masker level per ERB). The filter shapes showed a level dependence that qualitatively resembled the level dependence of filtering on the basilar membrane. The maximum gain of the tip filter tended to increase with increasing center frequency up to 1 kHz, but to remain roughly constant for higher frequencies.

164 citations


Proceedings ArticleDOI
08 Oct 2000
TL;DR: In this paper, seven methods of resonant-load control are compared for their ability to improve performance in the presence of a low-frequency (100 Hz) lightly damped resonance.
Abstract: High-performance servo drives are often limited by mechanical load resonance. In this paper, seven methods of resonant-load control are compared for their ability to improve performance in the presence of a low-frequency (100 Hz) lightly damped resonance. The seven methods are: notch filter, bi-quad filter, rigid body observers, low-pass filter, observer filtering, active resonance damping and center-of-mass control. Several of the methods are based on filtering the command signal; the remaining methods are based on signals acquired from an observer. Development of these methods is presented; each method is applied to a physical system and evaluated for effects on command response and dynamic stiffness.

143 citations


Journal ArticleDOI
01 Nov 2000
TL;DR: In this article, a weighted least squares estimation (WLSE) method with the covariance resetting technique was proposed to estimate the positive and negative voltage at abrupt transition. But, this method is not suitable for power conditioning equipment, since the response time of the system tends to be lengthened.
Abstract: If a negative sequence is generated by voltage sag and/or unbalance, it appears as an oscillating error in a synchronous reference frame (SRF). In power conditioning equipment, the exact value of a positive sequence is needed to achieve the unity power factor and constant output voltage, whereas the exact value of a negative sequence is needed for unbalance compensation. To measure the positive sequence separately from the negative sequence, a low pass or notch filter having a narrow bandwidth is normally used. However, such a filter causes a lot of phase delay, thus the response time of the system tends to be lengthened. A method of estimating the positive- and the negative-sequence voltages separately is presented, without a significant delay, by utilising the weighted least-squares estimation (WLSE) method with the covariance resetting technique. A frequency update law is also proposed to accommodate the frequency varying environments. The authors demonstrate through simulation and experiment the superior performance of the proposed scheme in measuring the positive- and the negative-sequence voltages at the time of abrupt transition. This method can be applied to uninterruptable power supplies (UPS), pulsewidth modulation (PWM) AC/DC converters, active filters, AC voltage compensators etc.

142 citations


Journal ArticleDOI
TL;DR: In this article, a semi-lumped parallel resonance circuit was employed to design a very compact low-pass filter, which enjoys sharper cutoff and fewer filter orders than those of the conventional lowpass filters.
Abstract: A semi-lumped parallel resonance circuit was employed to design a very compact low-pass filter. The semi-lumped shunt arm consists of a capacitor and a transmission line section. In such an arrangement, two finite attenuation poles can be generated near the passband edge. As a result, the proposed filter enjoys sharper cutoff and fewer filter orders than those of the conventional low-pass filters. In addition, these two attenuation poles can be properly designed to suppress the second and third harmonics generated from power amplifier and frequency source. A low-temperature cofired-ceramic (LTCC) multilayer-ceramic (MLC) low-pass filter and a PCB low-pass filter with a 0402 chip capacitor were designed and tested. Experimental results demonstrate the capability of this filter in harmonics and spurious suppression.

109 citations


PatentDOI
TL;DR: In this paper, a cascade of two narrow-band filters Ai(Z) and Bi(Zng) with a fixed delay is proposed to represent the feedback path in each subband.
Abstract: A new subband feedback cancellation scheme is proposed, capable of providing additional stable gain without introducing audible artifacts. The subband feedback cancellation scheme employs a cascade of two narrow-band filters Ai(Z)and Bi(Z)ng with a fixed delay, instead of a single filter Wi(Z)and a delay to represent the feedback path in each subband. The first filter, Ai(Z), is called the training filter, and models the static portion of the feedback path in ith subband, including microphone, receiver, ear canal resonance, and other relatively static parameters. The training filter can be implemented as a FIR filter or as an IIR filter. The second filter, B?I?(Z), is called a tracking filter and is typically implemented as a FIR filter with fewer taps than the training filter. This second filter tracks the variations of the feedback path in the i?th? subband caused by jaw movement or objects close to the ears of the user.

95 citations


Patent
Liza G. Boland1, Johan Janssen1
18 Dec 2000
TL;DR: In this paper, a filter structure is provided that facilitates the use of the filter as either a continuous delay Farrow filter or a selectable delay polyphase filter, and an inversion of Farrow filters is presented.
Abstract: A filter structure is provided that facilitates the use of the filter as either a continuous delay Farrow filter or a selectable delay polyphase filter. The less complex polyphase filter is used when the desired scale substantially corresponds to a defined phase of the polyphase filter, or when time or power is not available to achieve the desired scale exactly; otherwise, the continuous delay Farrow filter is used. By providing an ability to switch to a continuous delay, the number of stages of the polyphase filter can be reduced. Additionally, an inversion of a Farrow filter is presented that provides for a continuous delay decimation filter with substantially reduced computational complexity compared to a direct embodiment of a Farrow filter. This inverted filter is also configurable as a polyphase filter, to provide selectable scale-resolution capabilities.

93 citations


Patent
28 Sep 2000
TL;DR: In this paper, a direct conversion receiver (10) having a homodyning section (12) and a filter (18) is described, which includes a plurality of serially coupled high pass filter stages (20(1)-20(n)) acting as dc offset correction loop.
Abstract: A direct conversion receiver (10) having a homodyning section (12) and a filter (18) The filter (18) includes a plurality of serially coupled high pass filter stages (20(1)-20(n)) The high pass filter section (18) act as a dc offset correction loop The plurality of high pass filter stages (20(1)-20(n)) also enables the integration of the needed capacitors thus minimizing external components and connections Each one of the filter stages includes an amplifier (22) and a low pass filter (24) Each one of the low pass filters (24) is adapted to have the cutoff frequency thereof switch from an initial high cutoff frequency to a subsequent lower cutoff frequency A high pass filter stage (20(1)-20(n)) of a direct conversion receiver (10) is provided which includes in a low pass filter feedback section (24) thereof: a capacitor (C) and a resistor section (30) The resistor section (30) includes a switch for changing the resistance of the resistance section A switching arrangement (32) is included for charging the capacitor (C) rapidly during an initial, start-up time period or after a large step change in the gain of the amplifier (22)

77 citations


Patent
21 Jan 2000
TL;DR: In this article, a desired signal having a wide frequency band and including sequential symbols representing digital values is discriminated from a narrow band interfering signal with a carrier frequency in the wide band by initially applying both signals to a filter so both signals are passed to an output of the filter.
Abstract: A desired signal having a wide frequency band and including sequential symbols representing digital values is discriminated from a narrow band interfering signal having a carrier frequency in the wide band by initially applying both signals to a filter so both signals are passed to an output of the filter. In response to the filter output, estimates of the values of received symbols of the desired signal are derived and compared to the filter output to derive an error representing signal. A characteristic of the filter is controlled in response to the error representing signal so the filter is adjusted to reject the interfering signal and pass the desired signal.

67 citations


Patent
14 Dec 2000
TL;DR: In this article, a wavelength selective optical filter device (240) was proposed for receiving input radiation and outputting corresponding filtered output radiation, characterized in that the filter device included a plurality of at least partially coupled Fabry-Perot optical resonators (330, 340, 360; 360, 400, 430) for filtering the input radiation to generate the output radiation.
Abstract: The present invention provides a wavelength selective optical filter device (240) for receiving input radiation and outputting corresponding filtered output radiation, characterized in that the filter device (240) includes a plurality of at least partially mutually coupled Fabry-Perot optical resonators (330, 340, 360; 360, 400, 430) for filtering the input radiation to generate the output radiation, the filter device (240) being tunable from a first radiation wavelength to a second radiation wavelength by mutually detuning the resonators in a period where the resonators are being retuned from the first wavelength (λ1) to the second wavelength (λ2) so that the filter device (240) is substantially in a non-responsive state during the period. The resonators incorporate freely suspended mirrors (360, 430) which are electrostatically actuated to affect tuning of the resonators (330, 340, 360; 360, 400, 430). The filter device (240) is thereby capable of tuning between different wavelengths without tuning through wavelengths therebetween. The filter device (240) can be included into an add-drop filter (10) for providing channel add and drop functions when the filter (10) is incorporated in a multichannel WDM communication system (100).

65 citations


Patent
24 Feb 2000
TL;DR: In this paper, an apparatus for extracting activity information and position information from a composite signal generated by a motion sensor includes an analog-to-digital converter for converting the composite signal from analog to digital format.
Abstract: An apparatus for extracting activity information and position information from a composite signal generated by a motion sensor includes an analog to digital converter for converting the composite signal from analog to digital format. A wide-band low pass filter having a frequency response of about zero hertz to about ten hertz and a narrow low pass filter having a frequency response of about zero hertz to about 0.5 hertz filter the digitized composite signal. An adder subtracts the output of the narrow-band low pass filter from the output of the wide-band low pass filter. The resulting difference represents information regarding the activity level of the motion sensor, and the output of the narrow-band low pass filter represents information regarding the position of the sensor.

64 citations


Patent
02 Feb 2000
TL;DR: Adaptive Notch Filter (ANF) as discussed by the authors detects narrow band interferors above a threshold level within the CDMA signal by continuous scanning of a preset excision band associated with an AMPS system.
Abstract: A method and device which dynamically detects, tracks and filters interfering signals with sufficient speed (i.e. within one IS-95 CDMA data frame period, or 20ms) and fidelity to eliminate or greatly reduce the deleterious effects of narrow band interferor signals on a CDMA link. When inserted in an RF signal path an Adaptive Notch Filter (ANF) detects narrow band interferors above a threshold level within the CDMA signal. Detection is accomplished by continuous scanning of a preset excision band, e.g. a specified narrow band associated with an AMPS system. Detected interferors are then automatically acquired and suppressed. This is achieved by electronically placing a rejection notch at the frequency of the interferors. Multiple notch filters may be used to simultaneously suppress multiple interferors. In the absence of interferors a bypass mode is selected allowing the RF signal to bypass the notch. Upon detection of an interferor, a switch is made to a suppression mode where the interferor is steered through a first notch section and suppressed. Alternatively, an external control line may be used to select the bypass mode so that the signal is allowed to pass the notch section, regardless of interferor content.

Journal ArticleDOI
TL;DR: In this article, a multifunctional current mode filter using three current controlled conveyors and two grounded capacitors is described, which realizes high pass, band pass and low pass second order current transfer functions and provides independent pole-ω 0, and pole-Q 0 tuning through external current control.
Abstract: A multifunctional current mode filter using three current controlled conveyors and two grounded capacitors is described. The filter realizes high pass, band pass and low pass second order current transfer functions, and provides independent pole-ω 0, and pole-Q 0 tuning through external current control. The filter also displays low incremental parameter sensitivities. The simulation results on the filter support the theory.

Journal ArticleDOI
TL;DR: In this paper, a new current-mode universal filter with single input and three outputs employing only three dual output current conveyors and five grounded passive elements is presented, which realizes three filter functions simultaneously at high impedance outputs.
Abstract: A new current-mode universal filter with single input and three outputs employing only three dual output current conveyors and five grounded passive elements is presented. The proposed filter realizes three filter functions simultaneously, all at high impedance outputs. No component matching is required and all the passive and active sensitivities are low. Furthermore, the filter can also realize the notch and all-pass responses. Orthogonal control of the natural angular frequency and the quality factor is achieved.

PatentDOI
TL;DR: In this article, a low-pass filter of over-sampling type over-samples an input digital audio signal T1 and filters and removes the low frequency components of the produced aliasing noise.
Abstract: A low-pass filter (1) of over-sampling type over-samples an input digital audio signal T1 and filters and removes the low frequency components of the produced aliasing noise. A spectrum analysis circuit (3) calculates the spectrum strength of a predetermined band of the output signal from the low-pass filter (1). An expansion signal generating circuit (5) generates an expansion signal having higher frequency components from the output signal from the low-pass filter (1). A level control circuit (4) controls the level of the expansion signal according to the output signal from the spectrum analysis circuit (3). An adder (2) adds the level-controlled expansion signal to the output signal from the low-pass filter (1) thereby to generate a digital audio signal T2.

Journal ArticleDOI
TL;DR: A frequency-domain adaptive filter combined with a frequency-selective stepfactor control for acoustic echo cancellers is presented and may outrange stepfactor controls which work in the time domain.

PatentDOI
TL;DR: In this paper, a sound processor including a microphone, a pre-amplifier, a bank of N parallel filters, and an N-parallel filter bank is used to detect short-duration transitions in the envelope signal of each filter channel.
Abstract: A sound processor including a microphone (1), a pre-amplifier (2), a bank of N parallel filters (3), means for detecting short-duration transitions in the envelope signal of each filter channel, and means for applying gain to the outputs of these filter channels in which the gain is related to a function of the second-order derivative of the slow-varying envelope signal in each filter channel, to assist in perception of low-intensity short-duration speech features in said signal.

Patent
07 Jul 2000
TL;DR: In this paper, a method and an apparatus for adaptive wall (high-pass) filtering to remove low-frequency clutter in spectral Doppler I/Q data prior to FFT processing is presented.
Abstract: A method and an apparatus for adaptive wall (high-pass) filtering to remove low-frequency clutter in spectral Doppler I/Q data prior to FFT processing. The I/Q data is passed through a low-pass filter which rejects the flow frequency components above the clutter frequency range. The total power of the low-pass filter output is then computed. A system noise model is used to predict the mean system noise power in the low-pass filter output. The predicted mean noise power provides a noise threshold to gage how much clutter power is present in the current FFT packet. If no significant clutter is present, then wall filter selection logic will automatically select the lowest wall filter cutoff frequency stored in a filter coefficient LUT. If significant clutter power is present in the FFT packet, then the mean and variance of the clutter frequency over the FFT packet are estimated and then input into the filter selection logic, which selects the most suitable filter cutoff for the current clutter signal.

Patent
05 Dec 2000
TL;DR: In this article, a low pass filter, bandpass filter, or notch filter is used to isolate signaling environments in a power line communication system, and the filter may be coupled between power side wires and outlet side wires.
Abstract: Isolating signaling environments in a power line communication system involves the use of a filter to block power line data signals from entering and/or leaving a signaling environment while allowing power signals to pass to or from the signaling environment. Power line data signals are typically at a higher frequency than power signals, and therefore the filter is typically a low-pass filter, bandpass filter, or notch filter that blocks the higher frequency power line data signals while allowing the lower frequency power signals to pass through. The filter may be coupled between power side wires and outlet side wires. The filter may be integral to a circuit breaker for installation in a fuse box or other wiring system.

Patent
07 Jun 2000
TL;DR: In this paper, a narrow-band notch filter, realized by an in-fiber Bragg grating, is utilized to remove a component of the signal so the remaining signal can be measured.
Abstract: An apparatus for measuring the optical-signal-to-noise ratio (OSNR) of an optical system is adapted to function in single channel or in multi-channel wavelength division multiplexed optical communication systems. An optical signal spectrum and a center frequency characterize the optical signals. A narrow-band notch filter, realized by an in-fiber Bragg grating, is utilized to remove a component of the signal so the remaining signal can be measured. When multiple channels are present, a bandpass filter is used to select the part of the multiplexed signal to be measured. Both the narrow-band notch filter and the bandpass filter can be tunable to further extend the capabilities of the system. Two detectors are utilized with the power in the channel being measured by a low-gain detector and the power in the noise being measured by a high-gain detector. A processor receives the detector outputs, calculates OSNR, and controls the tunable components.

Journal ArticleDOI
TL;DR: A canonical, adaptive cascade-structure IIR notch filter to detect and track multiple time-varying frequencies in additive white Gaussian noise and is computationally simple, converges rapidly, and has good frequency resolution.
Abstract: We develop a canonical, adaptive cascade-structure IIR notch filter to detect and track multiple time-varying frequencies in additive white Gaussian noise. The algorithm uses allpass frequency transformation filters and a truncated gradient. Simulations indicate that our algorithm is computationally simple, converges rapidly, and has good frequency resolution.

Patent
22 Nov 2000
TL;DR: In this article, an improved implementation of an active-RC polyphase band-pass filter with transconductor cross-coupling between filter sections is presented, where the transconductance of each trans-conductor pair is set as the product of a desired radian center frequency and the capacitance of the corresponding matched capacitors.
Abstract: The invention is an improved implementation of an active-RC polyphase band-pass filter with transconductor cross-coupling between filter sections. The polyphase filter has first to fourth inputs, first to fourth outputs, two filter sections, and a block of transconductor pairs. The four input signals to the polyphase filter succeed one another in phase by 90 degrees. The two filter sections have reactances comprised of active balanced operational amplifiers with matched capacitors in their feedback loops. The block of transconductor pairs is coupled between corresponding reactances of each filter. The transconductance of each transconductor pair is set as the product of a desired radian center frequency and the capacitance of the corresponding matched capacitors. In the preferred embodiment, the transconductors are Gm cells and the transconductance of at least one Gm cell is field adjustable. The filter sections of the preferred embodiment can be a pair of low-pass third-order active-RC gaussian filters or a pair of low-pass sixth-order active-RC gaussian filters.

Patent
13 Sep 2000
TL;DR: In this paper, the authors proposed a band-separating filter bank and band-combining filter bank, where each filter bank incorporates a FIR low pass filter having an asymmetric impulse response as the prototype filter.
Abstract: An apparatus having a band-separating filter bank for separating a digital signal into a plurality of sub-band signals, to be processed or transmitted, and a band-combining filter bank for subsequently combining the resultant sub-band signals into a single digital signal, wherein each of the band-separating filter bank and band-combining filter bank incorporates a FIR low pass filter having an asymmetric impulse response, as the prototype filter of the filter bank. A significant reduction can thereby be achieved in the amount of overall group delay that results from the processing performed by these filter banks.

Journal ArticleDOI
TL;DR: In this article, an adaptive notch filter design that considers the body-bending vibration associated with the attitude control of a two-stage sounding rocket is discussed, which adapts the parameters while keeping the poles of the notch filter inside the unit circle on the z-plane, and satisfies the stability conditions of the filter at all times.

Patent
27 Apr 2000
TL;DR: In this paper, a position controller 30 applies a wide-band frequency control current of a 1st polarity to the 1st member (motor) 14 to make the 2nd member (read/write head) 18 start moving from a position on a track 20 to a position in a track 22.
Abstract: PROBLEM TO BE SOLVED: To improve the control over a read/write head positioning means under a temperature varying condition by making a system include a control loop which is coupled with a 2nd member and generates a wide-band frequency signal for positioning the 2nd member at a desirable position relatively to a 1st member. SOLUTION: A position controller 30 applies a wide-band frequency control current of a 1st polarity to the 1st member (motor) 14 to make the 2nd member (read/write head) 18 start moving from a position on a track 20 to a position on a track 22. When the read/write head 18 approaches the track 22, a control current of the opposite polarity is applied to the motor 14. The position controller 30 is equipped with temperature input 36 for inputting a signal corresponding to the actual temperature of a disk drive constitution element. This signal varies the frequency of a notch filter to match with the natural resonance frequency(f) corresponding to specific temperature of a device 10. The notch filter removes the natural resonance frequency(f).

Patent
28 Aug 2000
TL;DR: In this article, a surface acoustic wave antenna duplexer consisting of a transmitter line filter, a receiver line filter and an antenna terminal is considered, and a switching element is provided for varying a value of the capacitance or inductance so as to provide a function for varying either a pass band frequency or an attenuation band frequency of the SFA.
Abstract: A surface acoustic wave antenna duplexer constituted by a transmitter-line filter, a receiver-line filter and an antenna terminal, the transmitter-line filter and the receiver-line filter being connected in parallel with the antenna terminal as a common terminal; wherein at least one of the transmitter-line and receiver-line filters includes a top filter using the whole of a transmitter band or a receiver band as its pass band, a surface acoustic wave resonator filter, and a transmitter or receiver terminal, the top filter, the surface acoustic wave resonator filter and the transmitter or receiver terminal being disposed in this order viewed from the antenna terminal, the surface acoustic wave resonator filter including at least one additive capacitance or inductance; and wherein a switching element is provided for varying a value of the capacitance or inductance so as to provide a function for varying a pass band frequency or an attenuation band frequency of the surface acoustic wave resonator filter.

Patent
09 Mar 2000
TL;DR: In this paper, a lowpass filter and a bandpass filter are combined to provide a combined frequency response that provides for a stopband between the voiceband and the metering tone frequency.
Abstract: An apparatus and method provide for filtering of voiceband and specified tone frequencies of a mixed voice/data signal, such as an Asymmetric Digital Subscriber Line (ADSL) signal. A lowpass filter section passes voiceband content of the mixed signal and suppresses mixed signal content having frequencies falling within a databand of the mixed signal. A bandpass filter section is coupled to or integral with the lowpass filter section and passes the specified tone frequency, such as a metering or billing tone frequency. The lowpass and bandpass filter sections exhibit a combined frequency response that provides for a stopband between the voiceband and the metering tone frequency. The bandpass filter section effectively detunes a frequency response of the lowpass filter section to provide for the stopband. The stopband preferably provides for an insertion loss of 3 dB or greater between the voiceband and the metering tone frequency, and suppresses undesirable mixed signal content having frequencies falling within the stopband. The lowpass filter section and the bandpass filter section may each be implemented to include only passive components, such as passive magnetic components.

Journal Article
TL;DR: Using this method, the inductances and the capacitances of the filter can be calculated from known data such as the reactive compensation capacity, the tuned frequencies and the parallel resonant frequency, etc.
Abstract: Algorithm for the parameters of double tuned filter and the third order filter was briefly introduced.Different from usual interactive method,this algorithm is an accurate analytic method and has been successfully applied in practical engineering.

Proceedings Article
01 Jan 2000
TL;DR: In this article, a channel selection filter for a WCDMA direct conversion receiver is described, which achieves +25dBV out-of-band IIP3, + 77dBV IIP2 and 9.4nV/√Hz input-referred noise density.
Abstract: A channel selection filter for a WCDMA direct conversion receiver is described. The 5th order Chebyshev low-pass filter with a 0.01dB ripple has the -3dB frequency close to 2MHz. The circuit uses two on-chip high-pass filters for offset compensation. The real pole of the prototype is realized with a passive RC element which is the first stage in the filter. The filter achieves +25dBV out-of-band IIP3, + 77dBV out-of-band IIP2 and 9.4nV/√Hz input-referred noise density. The maximum gain is 67.7dB and the circuit draws 4.3mA from a 2.7V supply.

Journal ArticleDOI
TL;DR: An inverting type current conveyor (ICCII) is presented and its usefulness in active filter synthesis illustrated by presenting a new current-mode universal filter using this element.
Abstract: An inverting type current conveyor (ICCII) is presented and its usefulness in active filter synthesis illustrated by presenting a new current-mode universal filter using this element. The universal filter configuration based on the implementation of first-order allpass sections employs the absolute minimum number of passive and active components and hence leads to a filter circuit with very simple implementation.

Patent
02 Mar 2000
TL;DR: In this paper, a signal demultiplexer includes serially-connected 2-demuliplexing filter banks, including band-stop filters and down-samplers for culling sampling frequencies of output signals from filters to 1/2.
Abstract: A signal demultiplexer includes serially-connected 2-demultiplexing filter banks, including band-stop filters and down-samplers for culling sampling frequencies of output signals from filters to 1/2. When the 2-demultiplexing filter bank operates on four types of filters, first to fourth filters in an ascending order of frequencies, 2-demultiplexing filter bank is arranged in one of two configurations so that a first filter bank contains at least the first filter or the second filter, or a second filter bank contains at least the third filter or the fourth filter. The filter banks are connected in such a way that signals processed through the first filter are processed by the first 2-demultiplexing filter bank in a next-stage; signals processed through the second filter are processed by the second 2-demultiplexing filter bank in a next-stage. Signals processed through the third filter are processed by the first 2-demultiplexing filter bank in a next-stage; and signals processed through the fourth filter are processed by the second 2-demultiplexing filter bank in a next-stage.