Minehiro Nemoto

A novel monolithic isolator for a communications network interface IC

This is the first report of the development of a monolithic isolator that can provide a transformerless small communications network interface IC. A novel capacitively isolated technology using trench capacitor on the SOI substrate has been developed, and that has achieved a 1.2 kV monolithic isolator of 0.25 mm/sup 2/. The monolithic isolator exhibits a good transmission characteristic at the frequency of 10 MHz.

2.3 kVac 100 MHz multi-channel monolithic isolator IC

We have developed a multi-channel monolithic isolator IC that can provide 2.3 kVac isolation and 100 MHz signal transmission. This IC uses high voltage on-chip isolator technology using trench isolation with buried oxide on the SOI substrate and 0.4 /spl mu/m CMOS driver and receiver circuits. This technology enables to produce a 4-channel monolithic isolator with an area of 1.5 mm/sup 2/ and a consumption current of 0.5 mA per channel at a frequency of 50 MHz. We have also developed a one-chip modem interface IC that includes the multi-channel isolator and an analog front-end circuit.

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-µm-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.