Activity Detection Circuit Using FET Technology
Original Publication Date: 1983-May-01
Included in the Prior Art Database: 2005-Feb-07
A variety of data communications networks and elements require circuits for detecting the presence or absence of data transmission on a communications line or medium. Particularly, it is important to detect the presence of activity or its absence in order to detect failures at those points in the communications system. Failures can produce any level of DC signal on the input to an activity detection circuit and, hence, a requirement is to detect the fact that transitions have ceased in a fashion insensitive to DC input. The threshold detector circuit of the present disclosure avoids the problems inherent in a variety of prior designs, is insensitive to DC input, and has a sensitive threshold that provides an output when input signals have ceased.