Showing papers on "Bessel filter published in 1993"

A 20-MHz sixth-order BiCMOS parasitic-insensitive continuous-time filter and second-order equalizer optimized for disk-drive read channels

Abstract: A fast parasitic-insensitive continuous-time filter and equalizer integrated circuit that uses an active integrator is described. Circuit techniques for excess-phase cancellation and for setting the corner-frequency of the filter and equalizer are also described. These techniques result in a filter and equalizer chip with performance independent of process, supply, and temperature without employing phase-lock loops. The 20-MHz sixth-order Bessel filter and second-order equalizer operate from 5 V and generate only 0.24% (-52 dB) of total harmonic distortion when processing 2-V/sub pp/ differential output signals. The device is optimized to limit high-frequency noise and to amplitude equalize the data pulses in hard disk read-channel systems. The device supports data rates of up to 36 Mb/s and is built in a 1.5- mu m, 4-GHz BiCMOS technology. >

Design of a low-distortion 22-kHz fifth-order Bessel filter

Abstract: A linearity improvement technique employing passive resistors and current-steering MOS transistors as a variable resistance element is proposed to implement a low-distortion filter in CMOS technology. This proposed implementation relies on the linearity of the passive resistors and the tunability of the current-steering MOS transistors operating in the triode region to overcome the limited linearity performance in continuous-time electronically tunable filters. By using the existing systematic feedback loops in the active filters and placing the nonlinear elements inside the feedback, the distortion resulting from the nonlinear devices is greatly reduced by the filter loop gain. A 22-kHz fifth-order Bessel filter, its dynamic range optimized by applying Karmarkar's rescaling algorithm and self-tuned with a switched-capacitor reference resistor, demonstrates better than -90-dB THD with a 2-kHz, 4-V/sub pp/ signal in 5-V 2- mu m CMOS. >

Slimmer circuit technique

Abstract: A fast parasitic-insensitive continuous-time filter and equalizer integrated circuit that uses an active integrator is described. Circuit techniques for excess-phase cancellation, and for setting the corner-frequency of the filter and equalizer are also described. These techniques result in a filter and equalizer chip with performance independent of process, supply, and temperature without employing phase-lock loops. This 20MHz 6th order Bessel filter and 2nd order equalizer operate from 5V, and generate only 0.24% (-52 dB) of total harmonic distortion when processing 2 Vp-p differential output signals. The device is optimized to limit high-frequency noise and to amplitude equalize the data pulses in hard disk read-channel systems. The device supports data rates of up to 36 Mbps, and is built in a 1.5μ/4 GHz BiCMOS technology.

A low-distortion 22 kHz 5th-order Bessel filter

Abstract: A low-distortion MOSFET-C filter design is proposed. The proposed technique relies on the linearity of the passive resistors and the tunability of current-steering MOS transistors operating in the triode region. Placing the nonlinear elements inside the feedback loops and degenerating the MOSFETs by passive resistors, greatly reduces the distortion resulting from the nonlinear devices. A prototype 22-kHz Bessel filter automatically tuned to a switched-capacitor reference resistor has control voltage feedthrough below -100 dB, and measured linearity better than -90-dB THD (total harmonic distortion), with a 2-kHz, 4-V/sub pp/ voltage swing. Measured THD demonstrates an improvement of at least 30 dB over a conventional MOSFETC filter. The chip consumes 40 mW with a 5-V supply, and the active die area is 7 mm/sup 2/ in 2- mu m double-poly CMOS. >

A procedure for determining the largest computable order of Bessel functions of the second kind and Hankel functions

Abstract: Routines for the computation of Bessel functions of the second kind, Y/sub n/(z), and Hankel functions H/sub n//sup (1/)(z) and H/sub n//sup (2/)(z), may exhibit numerical overflow problems for large order n and small complex or real arguments z. An upper limit for the largest calculable order of these functions for a given argument, is derived. >

On the computation of Bessel functions of first kind

Abstract: A new algorithm is proposed for the evaluation of the Bessel function valuesJ p (x) with non-negative indexp and real positive argumentx. The basic ideas are the transfer of boundary conditions and the modified Prufer transformation applied to Bessel equation. Special attention is paid to the accuracy of the interval reduction and the stability of the auxiliary initial value problems.

Using Mathematicato teach Bessel functions

Abstract: By use of a computer and Mathematicathe elementary function cos x is visualized as a limit of the graphs of Taylor polynomials. A slight modification of the Taylor polynomials for cos xleads to a computer visualization of the graph of the Bessel function J0 (x).By similar modifications the student can develop and study the student's own analogues of trigonometric functions and of Bessel functions. A computer model of a vibrating elastic string, which can be animated, is produced by use of Fourier series and Mathematica.Similarly, a model of a vibrating elastic membrane is developed by use of J 0(x).The student can perform numerous computer experiments involving vibrating membranes with various initial conditions and involving study of the period of the motion. In addition, the student can study the motion of ‘pseudo‐membranes’ by use of the student's own analogues of Bessel functions.

Method and device for automatically correcting the characteristics of transmission lines

Abstract: The method consists essentially in configuring a chain of bandpass filters to be placed in series with a transmission line to be corrected, so as to make the characteristics of the corrected line substantially that of a reference filter, a Bessel filter for example. In the first place, the frequency response curve (BPL) of the line is brought above a template curve or between two framing template curves (BPG) via a selection of a particular combination of filters. Then one or more automatic sequences are carried out for setting the low cut-off frequency of the various filters chosen so as, step by step, to reach the frequency characteristic (BPR) of the chosen filter. Application to the improvement of transmission lines, of which the length and/or the characteristics are likely to vary from one application to another, such as, for example, those employed to transmit seismic data gathered in wells.

Low-distortion continuous-time R-MOSFET-C filters

Abstract: The R-MOSFET-C or R-MOSFET-R structure, which uses a set of passive resistors and current-steering MOS transistors as a variable resistance element, is proposed to implement low-distortion filter or multiplier in CMOS technology. This proposed technique relies on the linearity of passive resistors and the tunability of current-steering MOS transistors in triode. Placing the nonlinear elements inside feedback loops further reduces distortion in the filter implementation. The experimental results of a self-tuned 22 kHz fifth-order Bessel filter confirm the predicted theoretical performance, displaying negligible control voltage feedthrough and -90 dB total harmonic distortion (THD) with a 2 kHz, 4 V/sub p-p/ fully-differential signal, in a 5-V system. >

Function evaluation using expansions in Bessel functions of the first kind

Abstract: An iterative method is proposed for evaluation of fonctions that are expandable in series of Bessel functions of the first kind. The Bessel functions are evaluated by Miller's method, avoiding the need to determine their exact values. As an example, we describe algorithms for evaluation of the integral sine and the normal probability integral with an accuracy of to 10–12 significant digits.