Kenneth R. Laker

Convergence analysis of an algorithm for blind equalization

The authors consider a key algorithm for blind equalization and derive expressions for the evolution of the equalizer output error trajectory. The authors develop a model to examine the convergence behavior of this algorithm. Suitable approximations are incorporated into the model to facilitate analysis. The validity of these approximations is demonstrated for a typical communication channel. It is shown that even for a channel for which the assumption of Gaussianity of the equalizer input data may not be very good, the analysis presented predicts the convergence behavior reasonably well. >

Multiple-loop feedback topologies for the design of low-sensitivity active filters(Invited Paper)

Improved sensitivity performance of active filters in multiloop feedback (coupled) topologies is well known. Of the numerous design procedures available in the literature, in this paper those methods are reviewed which are based on first- or second-order building blocks in a feedback configuration. A statistical sensitivity measure is given which results in a realistic performance measure for the filters and which can be used to compare circuits and to optimize their design to achieve minimum sensitivity. Design procedures are provided for each topology, which result in realizations having minimum sensitivity and maximum dynamic range. Also, design tables for several examples are given, and the performance of some filters is demonstrated experimentally.

A simple hard-limited adaptive algorithm for blind equalization

An algorithm for adaptive blind equalization is proposed. It is interpreted as a sign version of a widely referenced algorithm for blind equalization, and it is demonstrated by way of simulations that the performance of this new sign algorithm is comparable to that of its unsigned version. A simple variable step-size scheme to accelerate the convergence process is also proposed. Simulation results are presented to demonstrate the significant improvements in the convergence rates that are obtained using this variable step-size scheme. >

Minimum sensitivity active (leapfrog) and passive ladder bandpass filters

It is shown that the sensitivities of resistively terminated LC ladder networks can be significantly reduced by inserting losses into the internal sections of the overall structure. Sensitivity improvements on the order of 20 percent are obtained for many of the filters considered. This observation is particularly useful in active ladder (leapfrog) synthesis where the additional losses are readily compensated, if necessary, by the gains of the active elements. To achieve optimum overall sensitivity, a previously introduced statistical multiparameter sensitivity measure is minimized.

Sign algorithms for blind equalization and their convergence analysis

In blind equalization a communication channel is adaptively equalized without resorting to the usual training sequence. In this paper we have introduced two new algorithms for blind equalization, which hard limit the equalizer input or the error at the output of the equalizer. These new algorithms are simple to implement and reduce the number of multiplications by approximately one-half. We show by way of simulations that the performance of the algorithm resulting from hardlimiting the error is comparable with the performance of the corresponding algorithm in which the error is not hardlimited. We formulate the new sign-error algorithm as a stochastic minimization of an error functional and demonstrate that the case of zero intersymbol interference corresponds to local minima of this error functional. We also present convergence analysis to predict the output mean square error in both these sign algorithms. Since the algorithms are highly nonlinear we incorporate several simplifying approximations and provide heuristic justifications for the validity of these approximations when the algorithms are operated in a typical practical environment. Computer simulations demonstrate the accuracy of the predicted convergence behavior.

Adaptive integrator-output bounding (AIB) for second order sigma-delta ADC

One of the essential issues of sigma-delta modulator (/spl Sigma//spl Delta/M) design is to properly scale the integrators to avoid clipping, which may cause information loss and hence severe degradation in SNR. This paper presents a new approach, adaptive integrator-output bounding (AIB), to second order 1-bit /spl Sigma//spl Delta/M design. By adaptively controlling the feedback coefficient of the first integrator, the AIB design significantly extends the unclipping input level to full scale, while that of the standard design is usually 3dB lower. Therefore, provided that the integrator scaling factors are the same, the AIB scheme increases the actual dynamic range of an unclipped system, and thus improves the peak SNR. Moreover, simulation results show that, compared to the standard system, the quantization noise of the AIB design is less dependent on the input levels, which indicates that the AIB scheme is closer to the linear model of the /spl Sigma//spl Delta/Ms.

An extended frequency range CMOS voltage-controlled oscillator

This paper presents an extended frequency range CMOS monolithic voltage-controlled oscillator (VCO) design. A negative feedback control algorithm is used to automatically adjust the VCO range according to the control voltage. Based on this analog feedback control algorithm, the VCO achieves a wide range without any pre-register settings. Low phase noise is achieved by using both coarse control and fine control in the VCO. A 600 MHz to 3.3 GHz monolithic CMOS PLL, based on this wide range and low phase noise VCO, has been fabricated in TSMC 0.18 /spl mu/m, 1.8 V CMOS technology and is used in many different applications such as FC, GE, and SONET etc.

A convergence model for the analysis of some blind equalization algorithms

A convergence model that predicts the evolution of the mean-square-error (MSE) trajectory of some blind equalization algorithms is presented. The authors consider the Sato algorithm and its computationally efficient sign versions, namely the Sato sign-error algorithm and the Sato sign-data algorithm. In their analysis they consider only the real system. Simulation results confirm the validity of the approach.<<ETX>>

Tonal behavior analysis of an adaptive second-order sigma-delta modulator

This paper analyzes the tonal behavior of an adaptive second-order sigma-delta modulator, which was developed and published by the same authors. Idle channel tones, caused by non-white quantization error, is not desirable in applications where the human ear is the end receiver. Besides their relatively small magnitude tones in the baseband, most sigma-delta modulators produce high-powered tones near f/sub s//2. It is a more serious problem because the clock noise near f/sub s//2 can couple these tones down into the baseband. Various simulations show that the more randomized nature of the aforementioned adaptive architecture makes it more advantageous in tonal behavior, particularly attractive in that it significantly reduces the dominant tone near f/sub s//2, which can not be reduced by dithering in a standard second order single-bit modulator. With comparison to the standard second-order sigma-delta modulators, the results are illustrated in both frequency and time domains.

IEEE - A Bold Leader in Changing the Essence of Technical Publications

Through the efforts of volunteers and staff, IEEE has, over the past 125 years, served the technology information needs of its stakeholders, while becoming a leader in the technical publishing industry. During these 125 years, IEEE relevant technologies, the needs of the global work force in IEEE technical communities, and the pace of technological development have undergone several paradigm shifts. This paper will examine how IEEE publications responded to and, in some cases, enabled these paradigm shifts. Arguably the most exciting and turbulent part of this journey has been the transition from print to electronic publishing, leading to the rich Internet based options we have today to receive our IEEE technology information. (Abstract) Keywords-component; formatting; style; styling; insert (key words) Internet, electronic publishing, digital documents, HTML, SGML, MathML, STIX, IPO, IEL, CSEL, OPeRA, JOLLY, EPIC, Xplore.