Patent ID: 6282001
Filing Date: 2001-08-28
Classification: H04B,H04L,H04M

Abstract:
An interface circuit having a first port and a second port, the first port having a transmit line and a separate receive line, the second port having a bidirectional line, the interface circuit electrically isolating the first port and the second port, the interface circuit comprising:a first optical isolation circuit electrically coupled to the transmit line, the first optical isolation circuit comprising:a first light source electrically coupled to the transmit line, the first light source generating a first illumination signal corresponding to a signal on the transmit line; anda first light detector optically coupled to the first light source for receiving the first illumination signal and generating a corresponding electrical signal;a line driver electrically coupled to the first light detector, the line driver driving the bidirectional line in response to the electrical signal generated by the first light detector;a differentiator having a first input, a second input and an output, the first input of the differentiator being electrically coupled to the bidirectional line;a second light detector optically coupled to the first light source for receiving the first illumination signal and generating a corresponding electrical signal, the second light detector being electrically coupled to the second input of the differentiator; anda second optical isolation circuit electrically coupled to the differentiator output, the second optical isolation circuit comprising:a first light source electrically coupled to the differentiator output, the first light source generating an illumination signal corresponding to an electrical signal generated at the differentiator output;a first light detector optically coupled to the first light source for detecting the illumination signal and generating a corresponding electrical signal, the first light detector being electrically coupled to the receive line; anda second light detector optically coupled to the first light source for detecting the illumination signal and generating a corresponding electrical signal, the second light detector being electrically coupled to the first input of the differentiator.