Design of a Bidirectional AC-Switch Control Circuit with Capacitive Isolation

In this paper, the design of an AC-switch control circuit is proposed with the following restrictions: compatible with CMOS technology; immune to a floating ground having the same frequency as the AC-switch control signal (1MHz) but a relatively high magnitude; and with short signal delay, i.e., no more than 1% of the signal cycle (10ns). The proposed capacitive-isolation circuit is designed in a CMOS HV 0.35µm technology. The simulation results have shown that the floating voltage immunity of the proposed circuit is up to 80Vpp, which is 24 times higher than the AC-switch control voltage, with a signal delay of 10ns, as required. The experimental results based on a PCB design are also given.