Charge-Coupled Device (CCD) Adaptive Discrete Analog Signal Processing

Abstract

A CCD adaptive signal processor is described which uses a so-called "clipped-data" least mean square (LMS) error algorithm to optimize the selection of tap weights in a CCD filter. A detailed description of a 16-tap monolithic silicon CCD analog adaptive filter is also presented. The filter is comprised of a basic Linear combiner formed with a nondestructively tapped CCD analog delay line and electrically reprogrammable MOS analog conductances as the tap weights. Two methods of varying the analog conductance are discussed: 1) variable VGS with fixed threshold voltage VT and 2) variable VT with fiied V G~ The former is performed with a CCD bidirectional charge control weight adjustment, whereas the latter is accomplished with MNOS memory transistors. To demonshate the feasibility of adaptive analog signal processing, a 2-tap weight CCD adaptive filter is described and experimental results presented. Applications include optimum filtering, prediction, noise cancellation, and system modeling.

Modified Clipped LMS Algorithm

“…, w n (N)] T is the weight vector of the estimator, X n is the vector of the input data sequence, which is assumed to be a stationary random process, N is the number of filter taps, e n is the estimation error, d n is the desired response, and µ is the step size. A simple change can be made to the LMS algorithm to obtain the CLMS algorithm [2,16,19]:…”

“…For applications in which slow adaptation is acceptable, the clipped LMS (CLMS) algorithm has an edge over the others in terms of speed of processing [16]. Also fast CLMS is proposed for increasing the speed of convergence [2].…”

Signed-gradient adaptive step size LMS algorithm for biomedical applications

“…In this paper, a class of signed-gradient adaptive step size LMS adaptive filters are proposed. Unlike the traditional sign LMS adaptive filters [15][16][17][18][19], the proposed algorithms introduce sign function to replace the gradient of squared error in the updating process of step size. In this paper, the performance of adaptation and noise reduction of gradient and signed-gradient adaptive step size LMS algorithms with dual adaptive filters are compared.…”

VIPMOS-a novel buried injector structure for EPROM applications

“…In this way, it is possible to cancel offsets in differential amplifiers [2]. E'PROM's may also find application in adaptive filters or in neural networks [3], [4]. In this paper we will describe a new structure for an EPROM device, which is realized by high-energy ion implantation and may be used in various EPROM applications.…”