High voltage SOI stacked switch with varying periphery FETs

The breakdown voltage of a FET stack is limited by the unequally divided voltage drop among the stacked FETs. A novel stack composed of varying periphery FETs is proposed. Uniform voltage distribution, and thus much higher breakdown voltage, can be achieved by carefully designing the periphery of each FET. A FET stack with varying periphery was designed and fabricated. Significant improvement in breakdown voltage was experimentally confirmed. Unlike the approach of inserting feed-forward capacitance, the breakdown voltage increase is achieved without isolation degradation.