Digitally controlled high-voltage analog switch array for medical ultrasound applications in thin-layer silicon-on-insulator process

We present a high-voltage bi-directional analog switch array designed and fabricated in thin-layer silicon-on-insulator technology for medical ultrasound applications. Thin-layer high-voltage SOI technology provides a factor-of-three reduction in specific on-resistance and capacitance over bulk silicon technologies (Letavic et al., Proc. IEEE ISPSD´97, pp. 49-52, 1997), resulting in substantial miniaturization of analog switch array function and inherently high performance. The integrated circuit contains five ±100 V 20 Ω bi-directional switches, including integrated gate drive, level shifting, and digital control in a total area of less than 6.5 mm². On-state power dissipation is measured at 15.7 mW at 50 kHz switch toggle, with -52 dB of off-state isolation in a 50 Ω load. This represents at least a factor-of-two increase in density for high-voltage analog switch arrays, and the resultant low-dissipation and miniaturization provides new system options for high performance 3D medical ultrasound applications.