Showing papers on "Bessel filter published in 1995"

New approximations to J/sub 0/ and J/sub 1/ Bessel functions

Abstract: New approximate solutions to the 0th- and 1st order Bessel functions of the first kind are derived. The formulations are based upon using a new integral with no previously known solution. The new integral in the limiting case is identical to the 0th-order Bessel function integral. It is solved in closed form, and the solution is expressed as a simple even order polynomial with integer coefficients. The polynomial coefficients are all of integer value. The 1st-order Bessel function approximation can then be found through a simple derivative. Comparisons are made between the exact solution, classic solutions, and the new approximation. The new approximation proves to be much more accurate than the classic small argument approximation. It is also sufficiently accurate to bridge the gap between the classic large and small argument approximations and has potential applications in allowing one to analytically evaluate integrals containing Bessel functions. >

Circuit technique that sets transconductance

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% (-52dB) of total harmonic distortion when processing 2Vp-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 36Mbps, and is built in a 1.5 μ/4GHz BiCMOS technology.

Bessel-mode formers

Abstract: The iterative algorithm developed allows calculating phase optical elements serving to transform incident coherent light into nondiffracting beams characterized by an unchanging transverse intensity distribution. Such nondiffracting light beams represent Bessel modes and are described as a superposition of a small number of Bessel functions with equal arguments. The results of numerical calculations are discussed.

Theory of self-phase-matching

Abstract: A theory of the recently discussed and demonstrated novel phenomenon of self-phase-matching [B. Glushko, B. Kryzhanovsky, and D. Sarkisyan, Phys. Rev. Lett. 71, 243 (1993)] is given by representing the conical beam, produced in the experiments, by a Bessel beam and as a superposition of Bessel beams. The predictions of the theory with the superposition of Bessel beams are in conformity with the observed behavior.

A low-distortion BiCMOS 7th-order Bessel filter operating at 2.5 V supply

Abstract: This paper presents the design of a 7th-order continuous-time Bessel filter using a new low-voltage and highly-linear BiCMOS OTA. A high-gain and parasitic-insensitive integrator is obtained by using an active capacitor scheme. The filter has been fabricated in a 1 /spl mu/m, double-poly 6-GHz BiCMOS process. The filter is operated at 2.5 V supply and has a nominal -3 dB cut-off frequency set at 600 kHz. The inband group delay variation is less than 10 ns. The THD measured with a 100 kHz input signal is less than -49 dB for a 2 V/sub pp/ amplitude. The filter can be frequency tuned with an external resistor over almost a decade with a gain variation less than 0.2 dB. The dynamic range is about 77 dB. A CMRR of 53 dB in the passband is observed, thanks to a careful common-mode control strategy.

Quadrature FM detector

Abstract: A quadrature FM detector apparatus for demodulating an FM signal so as to produce a baseband audio signal utilizes a delay circuit 103, which may comprise a filter or even a digital shift register, for delaying the FM signal by one-quarter of its frequency. The delayed FM signal is then mixed with the original signal to obtain a baseband audio signal. The filter may be a two stage, four pole Bessel filter. Other filters such as Gaussian, Butterworth, all-pass filters may be used instead.

GMSK modulated analogue signal generation system

Abstract: The system provides a GMSK modulated analogue output signal of limited bandwidth from a supplied digital input signal, using a Bessel filter of eighth order, directly supplied with the frequency modulated input signal in serial digital form. The Bessel filter has a lowpass transmission characteristic, with the analogue output signal obtained at its output and is used as an input filter for transmission of a limited bandwidth analogue signal.

Calculation of Bessel functions by using continued fractions

Abstract: We propose a new method for the calculation of Bessel functions of the first kind of integral order. By using the Laplace transformation, we solve a linear differential equation that defines the generating function for the Bessel functions expressed in terms of continued fractions.