Patent ID: 6930513

Claim:
A simultaneous bi-directional signal transmission system comprising a first semiconductor device, a second semiconductor device, and at least one transmission line which connects the first and second semiconductor devices, wherein the first semiconductor device includes: a first output MUX which receives a first binary data and converts the first binary data into a first signal having one of at least four levels; a first transmitter which is connected to the first output MUX and outputs the first signal via the transmission line to the second semiconductor device; a first receiver which compares at least one reference voltage selected by the first signal with a third signal input via the transmission line and outputs the comparison result; and a first input encoder which detects a second binary data based on the comparison result output from the first receiver, and wherein the second semiconductor device includes; a second output MUX which receives the second binary data and converts the second binary data into a second signal having one of at least four levels; a second transmitter which is connected to the second output MUX and outputs the second signal via the transmission line to the fist semiconductor device; a second receiver which compares at least one reference voltage selected by the second signal with the third signal input via the transmission line and outputs the comparison result; and a second input encoder which detects the first binary data based on the comparison result output from the second receiver.