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Transversal Filter

IP.com Disclosure Number: IPCOM000083565D
Original Publication Date: 1975-Jun-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Riso, V: AUTHOR

Abstract

Shown is a transversal filter comprising a bucket brigade delay line, wherein the number of taps and consequently the number of attenuators are reduced by recirculating data in the delay line at a speed (N+1)/T, N being the number of stages of the delay line and 1/T being the sampling rate.

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Transversal Filter

Shown is a transversal filter comprising a bucket brigade delay line, wherein the number of taps and consequently the number of attenuators are reduced by recirculating data in the delay line at a speed (N+1)/T, N being the number of stages of the delay line and 1/T being the sampling rate.

In a transversal filter, output samples y(i) are given by the expression:

(Image Omitted)

where x(i-k) terms represent previous input samples. The number of coefficients a is limited and is chosen equal to five in the practical implementation shown on the figure.

The bucket brigade delay line comprises five stages. Each stage is composed of two field-effect transistors T2 and T1, the gates of which are controlled by pulse train phi 2 and phi 1 and two capacitors C2 and C1, as shown in stage 1. Stages 2, 3 and 4 are identical to stage 1. Output stage 5 is represented in detail.

The various products a(k) x(i-k) are calculated through attenuator ATT which is digitally controlled.

Input samples are applied to input IN of field-effect transistor T'1 controlled by pulse train phi'1, the frequency of which is 1/T. Input samples propagate in the delay line and recirculate under control of field-effect transistor T''l which is controlled by pulse train phi''1.

During an initialization period successive input samples are shifted to nodes 2, 3, 4, 5, 6 of the delay line and at rate phi 2, they are successively applied to the attenuator to be multiplied by the proper co...