US 4,307,355 A · Method and circuit arrangement for the operation of recursive filter circuits or analog storage circuits constructed according to the charge coupled device (CCD) principle

Abstract

The invention relates to a method for operating recursive filter circuits or analog storage circuits constructed according to the charge coupled device principle and relates to a circuit arrangement for implementing the method, in which method only each respective second stage of a CCD is occupied with a charge representing a sampling value of an analog signal and the respective stages lying between these stages concerned and left empty. Known circuits constructed according to the CCD principle conduct the signal from the output stage of a CCD chain to the input of the CCD loop via an amplifier to which the input signal is supplied at the same time. Thereby, the amplification must very precisely amount to one. An amplifier of the high stability required thereto which is arranged in common with the concerned CCD on a chip cannot be satisfactorily realized. By means of the invention, a method is specified in which the amplifier is replaced by means of modulation of a sampling value with a reference signal and by means of a charge amount corrected in accord with the result of the modulation.

Claims11

Dependent claims

Method for operating recursive filter circuits having a first charge coupled device and a second charge coupled device (CCD) connected to feedback a signal from the output of the first device back to the input of the first device, each device having a plurality of storage stages which are connected to clock pulses for shifting charges from stage to stage in the charge coupled device, comprising the steps of:

in the first CCD providing a sequence of charges such that a first stage of the CCD contains a sampling value of an analog signal, a second stage is left empty, a third stage contains a reference value charge of a reference signal, and the fourth stage is left empty, said pattern being repeated in successive stages of the first CCD;
evaluating an amplitude of each of the reference charges as they occur at the output of the first CCD and, if the amplitude of the reference charge exceeds a predetermined threshold value, the excess charge is removed prior to feedback through the second CCD, whereby the influence of undesirable inverse currents on the operating point of the filter circuit is eliminated.

Dependencies are inferred from the claim text.

Method and circuit arrangement for the operation of recursive filter circuits or analog storage circuits constructed according to the charge coupled device (CCD) principle

Life of this patent

Method and circuit arrangement for the operation of recursive filter circuits or analog storage circuits constructed according to the charge coupled device (CCD) principle

Life of this patent

Abstract

Claims11