A method and system provide security for a communication network and for one or more nodes within the network. The first pulse generator block is arranged to be responsive to rising edges of said input signal, and the second pulse generator blocks is responsive to falling edges of said input signal. In one embodiment, the video drive signal is indicative of the sum of or the difference between the positive power supply voltage and the video signal and the current drive voltage is indicative of the difference between the positive power supply voltage and the video drive signal.