Showing papers on "Bessel filter published in 2005"

A novel CMOS operational transconductance amplifier based on a mobility compensation technique

Abstract: This brief describes a new linear operational transconductance amplifier (OTA) and its application to a ninth-order Bessel filter. To improve the linearity of the OTA, we employ a mobility compensation circuit which combines the transistors operating in the triode and the subthreshold regions. The proposed technique enhances the linearity of the transconductance without loss of the input swing range. The proposed OTA shows /spl plusmn/0.5% Gm variation and the total harmonic distortion of less than - 60-dB over the input range of /spl plusmn/0.8-V. The ninth-order Bessel filter employing the proposed OTA has been implemented in a 0.35-/spl mu/m n-well CMOS process under 3.3-V supply voltage. It shows the cutoff frequency of 8 MHz and the power consumption of 65 mW.

Theory of the unstable Bessel resonator.

Abstract: A rigorous analysis of the unstable Bessel resonator with convex output coupler is presented. The Huygens–Fresnel self-consistency equation is solved to extract the first eigenmodes and eigenvalues of the cavity, taking into account the finite apertures of the mirrors. Attention was directed to the dependence of the output transverse profiles; the losses; and the modal-frequency changes on the curvature of the output coupler, the cavity length, and the angle of the axicon. Our analysis revealed that while the stable Bessel resonator retains a Gaussian radial modulation on the Bessel rings, the unstable configuration exhibits a more uniform amplitude modulation that produces output profiles more similar to ideal Bessel beams. The unstable cavity also possesses higher-mode discrimination in favor of the fundamental mode than does the stable configuration.

The beat of a fuzzy drum: fuzzy Bessel functions for the disc

Abstract: The fuzzy disc is a matrix approximation of the functions on a disc which preserves rotational symmetry. In this paper we introduce a basis for the algebra of functions on the fuzzy disc in terms of the eigenfunctions of a properly defined fuzzy laplacian. In the commutative limit they tend to the eigenfunctions of the ordinary laplacian on the disc, i.e. Bessel functions of the first kind, thus deserving the name of fuzzy Bessel functions.

Generalization of the Modified Bessel Function and Its Generating Function

Abstract: This paper presents new generalizations of the modified Bessel function and its generating function. This function has important application in the transient solution of a queueing system. 2000 Mathematics Subject Classification: 33C10, 33-02, 60K25

Channel filters for microelectronic receivers of wireless systems

Abstract: A short overview of receiver architectures and low-pass filter specifications for wireless systems is reported. Two design procedures of low-pass filters for communication system are discussed. A CMOS transconductance-capacitor (G/sub m/-C) filter with enhanced linearity is presented as the first one. The proposed design is based on a transconductance amplifier with enhanced linearity. For the elimination of the amplifier harmonic level the compensation principle is used. The device was realized as a balanced fifth-order 1 MHz low-pass Bessel filter in 0.35 /spl mu/m CMOS process. The filter operates with a low supply voltage of +2.5 Volt. Its power consumption is 8.25 mW, the input referred RMS noise is 120 /spl mu/V (0.01 + 2 MHz), and HD3 (1 V/sub P-to-P/ @ 1 MHz) is -54 dB. Alternatively a new approach to the design of high-frequency filters with low power consumption is presented. The idea is to use current mode and voltage mode active elements with enhanced frequency range. These elements are second generation current conveyors and voltage buffers, those are used to implement integrators. The filter is realized as a switched-capacitor circuit based on an integrator chain with multi feedback loops. As an example a CMOS switched-capacitor filter with 1 MHz cut-off frequency is presented. The device was realized as an unbalanced fifth-order low-pass Chebyshev filter in 03 /spl mu/m CMOS process. The filter operates with supply voltage varying from +2.5 V to +3 V. Depending on the supply voltage its power consumption is from 3 mW to 10 mW, the input referred RMS noise is 1.9 mV (0.02 + 2 MHz @ +3 V), and HD3 (2 V/sub P-to-P/ @ 900 kHz @ +3 V) is -54 dB.

A new polynomial approximation for J/sub v/ Bessel functions

Abstract: New approximate solutions to the v-order Bessel function of the first kind are derived The solution is expressed as a polynomial for Bessel function of all fractional order polynomial Comparisons are made between the exact solution and the new approximation One utility of this derivation is to allow researchers to analytically evaluate integrals containing Bessel functions

An allpass filter design method with application to piano string synthesis

Abstract: A nonparametric allpass filter design method for matching a desired group delay as a function of frequency is presented. The technique is useful in physical modeling synthesis of musical instruments exhibiting dispersive wave propagation in which different frequency bands travel at different speeds. While current group delay filter design methods suffer from numerical difficulties except at low filter orders, the technique presented here is numerically robust, producing an allpass filter in cascaded biquad form, and with the filter poles following a smooth loop within the unit circle. The technique was inspired by the observation that a pole‐zero pair arranged in allpass form has 2π total group delay when integrated around the unit circle, regardless of the pole location. To match a given group delay characteristic, the method divides the frequency axis into sections containing 2π total group delay, and assigns a pole‐zero allpass pair to each. In this way, the method incorporates an order selection techn...

Modeling and design of high-order phase locked loops

Abstract: In this paper a new stable high order Digital Phase Lock Loop (DPLL) design technique is proposed. This technique uses linear theory to design the DPLL. The stability of the DPLL is guaranteed by placing a restriction on the system gain. This stability boundary is found by transforming the system transfer function to the Z-domain and plotting the root locus of the LPLL for values of gain where all the system poles lie inside the unit circle. The max value of gain where all the poles lie inside the unit circle is the stability boundary. It is shown that the stability boundary of the LPLL is comparable to the stability boundary of the DPLL. Finally where the above Bessel filter system produces slow lock, gear shifting of the DPLL components is considered. This allows the DPLL to start off with a wide loop bandwidth and switch to the narrow bandwidth once the system has locked.

A wideband subsample delay estimation technique

Abstract: An adaptive algorithm for estimating the delay between two noisy wideband signals is presented. The method is based on the explicit time delay estimation and breaks the fractional delay filter into two parts, one as the pre-filter and the other as the fractional part. The adaptation changes the second filter. A bias free estimate of the delay is produce, which is showed to be convergent in both mean and variance. This technique in comparison with the conventional Sinc filter used for wideband signals does not need to a large number of changing terms for the filter and also speeds up the convergence.

A self-equalization band pass filter involving complex transmission zeros and its equivalent circuit in the Foster type circuit

Abstract: This paper proposes a design method for a bandpass filter with characteristics close to ideal ones in which the amplitude and group delays are simultaneously flat in the passband and selectivity is assured in the stopband by means of an attenuation pole. In the present approach, first a method of designing the network function of a low pass prototype is proposed in which the group delay and the amplitude can be made flat at the same time over the same bandwidth by means of self-equalizationThis refers to equalization carried out by the design of only the network function without an external equalizer. using complex transmission zeros. It is shown that a circuit network with this characteristic can be synthesized by a Foster type circuit. Further, it is shown that degradation of the group delay, which is unavoidable in conventional methods, can now be suppressed if frequency transformation is carried out directly to the individual circuit elements in the Foster type circuit. By means of this frequency transformation, a Foster type equivalent circuit is derived for a bandpass filter which faithfully performs frequency shifting of the characteristic of the low pass prototype. As a design example, a bandpass filter is presented in which a ninth-order Bessel filter is self-equalized by a set of complex transmission zeros and a set of transmission zeros on the imaginary axis. © 2005 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 88(4): 54–61, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20086