A high-voltage monolithic isolator for a communication network interface

We have developed a multichannel monolithic isolator that can provide 2.3 kV ac isolation and 100-MHz signal transmission. The isolator uses high-voltage, on-chip isolator technology including trench isolation with buried oxide on the silicon-on-oxide (SOI) substrate and 0.4 mum CMOS driver and receiver circuits. This technology lets us produce a four-channel monolithic isolator with an area of 1.5 mm(2) and a consumption current of 0.5 mA per channel at a frequency of 50 MHz. These operating values suggest that the monolithic isolator can miniaturize the communication interface and reduce power consumption since discrete devices, such as transformers and opto-couplers, are unnecessary. We have also developed a one-chip modem interface LSI that includes the multichannel isolator and an analog front-end circuit.