Circuit arrangement for A/D conversion of amplitude-modulated signals of at least one measured-quantity pick-up

摘要

A circuit arrangement is created for A/D conversion of amplitude-modulated signals of at least one, in particular inductive measured-quantity pick-up, which is fed with a carrier frequency voltage and produces a measured-quantity-proportional amplitude modulation. The aim is the creation of an efficient circuit for fast and accurate A/D conversion of amplitude-modulated sinusoidal signals. The invention achieves the object of converting the method of successive approximation into a suitable circuit for fast and accurate A/D conversion of amplitude-modulated sinusoidal signals. Via a first comparator (14), a comparison is made between the measured-quantity-proportional alternating voltage and a direct voltage set by successive approximation at an accurately defined time and the said time is defined with the aid of a second comparator (15). The result of the comparison is stored for the duration of one period of the alternating voltage and provided to a microcomputer (22) which immediately provides a new direct voltage for the first comparator (14) with the aid of a D/A converter (12) in accordance with a successive approximation. <IMAGE>