Patent ID: 8890565

Claim:
A logic signal transmission circuit comprising: a driving circuit configured to convert an input digital signal to a differential signal pair having a first digital signal and a second digital signal; an isolation section configured to block direct current and to pass the differential signal pair, the isolation section including a first isolation barrier and a second isolation barrier, the first isolation barrier configured to pass the first digital signal, the second isolation barrier configured to pass the second digital signal; and a latch section including a first latch circuit connected to an output terminal of the first isolation barrier and a second latch circuit connected to an output terminal of the second isolation barrier, wherein the first latch circuit has even numbers of first inverters which are connected in a first loop and configured to output a first logic signal by turning ON and OFF a power supply voltage in a complementary manner, a first input impedance of the first latch circuit is set so that when a logic level of the first digital signal changes, a first transient voltage inputted through the first isolation barrier to the first latch circuit changes across a first threshold voltage of the first latch circuit, when the first transient voltage changes across the first threshold voltage, a logic level of the first logic signal changes, the second latch circuit has even numbers of second inverters which are connected in a second loop and configured to output a second logic signal by turning ON and OFF a power supply voltage in a complementary manner, a second input impedance of the second latch circuit is set so that when a logic level of the second digital signal changes, a second transient voltage inputted through the second isolation barrier to the second latch circuit changes across a second threshold of the second latch circuit, and when the second transient voltage changes across the second threshold voltage, a logic level of the second logic signal changes.