Protection from inbound signal noise caused by inductively coupled outbound signal transitions by controlling decision threshold

摘要

A noise-immune electronic circuit includes an input circuit for receiving an inbound signal through an input transmission line and comparing the inbound signal with a decision threshold to produce input data of the electronic circuit having one of predefined discrete levels depending on relative magnitudes of the inbound signal and the decision threshold and an output circuit for receiving output data of the electronic circuit and producing therefrom an outbound signal and forwarding the outbound signal onto an output transmission line. The input and output transmission lines are inductively coupled together so that a noise is introduced to the received inbound signal when a voltage transition occurs in the forwarded outbound signal. To avoid decision errors of the input circuit, a noise protection circuit is provided, which is responsive to a voltage transition of the output data of the electronic circuit for controlling the decision threshold at timing coincident with the noise produced in the inbound signal so that the input circuit makes no decision errors in the presence of the noise.