An isolation system is provided that is suitable for use in telephony, medical instrumentation, industrial process control and other applications. Preferred embodiments of the invention comprise a capacitive isolation barrier across which a digital signal is communicated. The system provides a means...http://www.google.de/patents/US6385235?utm_source=gb-gplus-sharePatent US6385235 - Direct digital access arrangement circuitry and method for connecting to phone lines
