4-kV 100-Mbps monolithic isolator on SOI with multi-trench isolation for wideband network

We have developed a monolithic isolator that provides an isolation voltage of 4 kV and a signal transmission rate of 100 Mbps. Two circuit areas are isolated using 34 trenches on a bonded SOI with 3-mum-thick buried oxide. The inequality in the voltages applied to the trenches is reduced using polysilicon resistors parallel to the trenches, which increases the isolation voltage from 2.4 to 4.0 kV. The isolator consists of two series of high-voltage capacitors in which silicon on buried oxide and a third metal are used as electrodes. We have also developed a network interface LSI with 4-channel isolators, which provide 4-kV isolation and 100-Mbps transmission.