Abstract: Provided is a protection circuit for high speed signal communication via a two-wire connection between the two output terminals of a PECL driver and the two input terminals of a PECL receiver. The PECL driver and receiver are supplied with power from individual power supplies. The protection circuit includes two diodes connected in series with a respective wire with their cathodes electrically coupled to the respective output terminal of the PECL driver and their anodes electrically coupled to the respective input terminal of the PECL receiver, and two resistors connected between the PECL receiver power supply and the anodes of the respective diode. The resistance of the resistors ensures forward biasing of the diodes when the receiver power supply is supplying power. A capacitor may be connected in parallel with the respective diodes.