SIMULTANEOUS LVDS I/O SIGNALING METHOD AND APPARATUS

摘要

First and second devices may simultaneously communicate bidirectionally with each other using only a single pair of LVDS signal paths. Each device includes an input circuit and a differential output driver connected to the single pair of LVDS signal paths. An input to the input circuit is also connected to the input of the driver. The input circuit may also receive an offset voltage. In response to its inputs, the input circuit in each device can use comparators, gates and a multiplexer to determine the logic state being transmitted over the pair of LVDS signal paths from the other device. This advantageously reduces the number of required interconnects between the first and second devices by one half.

主权项

1. An LVDS input circuit comprising:
(a) a data input lead; (b) a first LVDS signal path; (c) a second LVDS signal path; (d) an inverter having an input connected to the data input lead and an inverting output; (e) an LVDS receiver having a non-inverting input connected to the first LVDS signal path, an inverting input connected to the second LVDS signal path, and an output; (f) window comparator circuitry including:
(i) a first comparator having a non-inverting input connected to the first LVDS signal path, an inverting input connected to the second LVDS signal path, and an output;(ii) a second comparator having a non-inverting input connected to the second LVDS signal path, an inverting input connected to the first LVDS signal path, and an output;(iii) an OR gate having one input connected to the output of the first comparator, another input connected to the output of the second comparator, and an output; and (g) a multiplexer having one input connected to the inverting output of the inverter, another input connected to the output of the LVDS receiver, a control input connected to the output of the window comparator, and an output.