Isolator and a modem device using the isolator

A communication system comprising:

• a transceiver;
• an application controller to transmit and receive signals through said transceiver;
• and
• an isolator to insulate and separate between said transceiver and said application controller,
• wherein said isolator includes
• a semiconductor substrate,
• primary and secondary side circuits provided on said semiconductor substrate and insulated from each other, and
• a capacitive insulating means positioned on said semiconductor substrate for transferring signals between said primary and secondary sides, and for insulating and separating said primary side circuit from said secondary side circuit.