New method of interference rejection in fast analogue-digital convertors

A new method of solving the problem of interference rejection in high-speed analogue-digital (a.d.) convertors is given. The measurement speed obtained in such a way in multichannel data-acquisition systems is much higher (up to two orders of magnitude) than that obtained with filters and integrating a.d. convertors which have the same rejection of line frequency. Different solutions of interference rejection, based on the same method, are presented. A time interval of only 20 ms is required to achieve line-frequency suppression higher than 50 dB, so that the fast a.d. convertors could replace the integrating ones. The method proposed is especially suitable for application in online computer systems.