Butterworth filter

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

A design framework for low power analog filter banks

Abstract: We detail the design of multiresolution analog filter banks, linear models of cochlear function, with power dissipation being a prime engineering constraint. We propose that a reasonable goodness criterion is the information rate through the system, per watt of power dissipated. Speech applications requiring filter banks with a wide frequency tuning range, from 20 Hz to 20 kHz, and low power consumption make the transconductance-C integrator in subthreshold CMOS the preferable integrator structure. As an example, the dynamic range of a lowpass filter is computed and subsequently used to design a filter bank that models faithfully cochlear micro-mechanics. The power consumption of the entire filter bank is computed from analytical expressions and is estimated as 355 nW, at 68 kb/s overall information rate at the output of the system.

Tunable Balanced Bandpass Filter With Wide Tuning Range of Center Frequency and Bandwidth Using Compact Coupled-Line Resonator

Abstract: A tunable balanced bandpass filter using a short coupled-line resonator is proposed. The design aims at achieving a wide tuning range in the differential-mode for both of the center frequency and bandwidth with high common-mode suppression. The proposed filter uses a short section (about one-eighth of one wavelength) of parallel-coupled lines connecting the differential ports of the device and five pairs of varactors. A theoretical analysis using the even-odd mode theory is presented to verify the tunability of the design and calculate the initial values of its design parameters. For validation, a prototype is designed, fabricated and tested. The measured results indicate that the differential-mode tuning range for the center frequency and 3 dB- bandwidth extend from 0.58 to 1.22 GHz, and from 65 to 180 MHz, respectively, with more than 30 dB of common-mode suppression in the operating differential-mode passband. Moreover, the proposed device has a compact size (with respect to the guided wavelength) of only $0.12\lambda_{G}\times 0.08\lambda_{G}$ .

Tuning method for integrated continuous-time filters

Abstract: A high-frequency integrated continuous-time filter with built-in test mode. The present invention provides the ability to easily track the cutoff frequency of the filter without the additional power and area requirements and noise sources present in prior art master/slave tuning schemes. Furthermore, the filter being tested is the actual filter that is used to process signals, unlike the prior art where a similar but separate filter or oscillator is used to tune the bias values for both circuits. Better tuning accuracy is thus obtained in the present invention. The circuit is designed to oscillate in test mode at the cutoff frequency of the filter. Oscillation is achieved by moving the poles of the filter from the left half-plane either onto the imaginary axis or into the right half-plane. The filter frequency accuracy is established by trimming the frequency of the oscillation in test mode during wafer probe or by adjusting the circuit biasing to tune the cutoff frequency in test mode during power-up or between reads in a memory system. The oscillation is disabled during normal operation of the filter.

Data converter with minimum phase fir filter and method for calculating filter coefficients

Abstract: In accordance with an embodiment of the invention, a data converter is disclosed employing at least one minimum phase FIR filter. The data converter includes an analog-to-digital converter for converting an incoming analog signal into a plurality of digital signal samples, followed by a minimum phase FIR filter to filter the digital signal samples. Alternatively, the data converter includes a digital-to-analog converter preceded by a minimum phase FIR filter to filter a plurality of digital signal samples that are converted into an analog signal by the digital-to-analog converter. The data converter may include both analog-to-digital and digital-to-analog conversion. In a preferred embodiment, the minimum phase FIR filter is an optimum minimum phase FIR filter. A method for precisely calculating the filter coefficients of an optimum minimum phase FIR filter is also disclosed.

Performance of cascaded misaligned optical (de)multiplexers in multiwavelength optical networks

Abstract: We use computer simulation techniques to evaluate the limitations on laser misalignment tolerances for multiwavelength optical networks with a cascade of 2 to 100 (de)multiplexers modelled as either first-order filters or third-order Butterworth filters. The results are dependent on the number of (de)multiplexers used, on the bit rate, and on the filter characteristics. We find that both the magnitude and the phase characteristics of the (de)multiplexer transfer function are important in determining the distortion-induced penalties. The allowable laser misalignment tolerances, at 10 Gb/s and for systems using (de)multiplexers modelled as third-order Butterworth filters, vary from /spl plusmn/78 GHz (/spl plusmn/0.63 nm) for systems with a cascade of 2 filters to /spl plusmn/18 GHz (/spl plusmn/0.15 nm) for systems with a cascade of 100 filters.