Low power CMOS optoelectronic transmission system design

Abstract

Catheter based endovascular operations are used for diagnosis and treatment as minimally invasive procedures. Most of these operations are held under X-ray uoroscopy which is harmful due to incident radiation and chemical agents used for increasing contrast ratio. However, MRI, with high soft tissue contrast and eliminates ionizing radiation, is a candidate to replace old techniques which are used for catheter based operations. An optoelectronic system to be used in a MR environment as a part of a catheter detection system is proposed. The optoelectronic system is composed of an external laser driver, an optoelectonic CMOS power supply, an LED driver and an optical transmission path which is fabricated by using MEMS techniques. The external laser driver enables modulation of power laser which has a power up to 200 mW with a wave length 660 nm. The CMOS power supply, fabricated in UMC 0.18 m process, is composed of photodiodes, which have an e ciency of 5% optical-toelectrical conversion, and a DC/DC converter to boost photodiode voltage of 0.6 V to 1.2 V. A supply independent LED driver, which supplies 2 mA to an IR LED with a current consumption of 138 A, has been designed. A Si platform which is composed of a V-groove and a mirror, is designed and fabricated by using wet etching techniques. Finally, a front-end circuit is described to detect optical signals which carry catheter localization data on their frequency.