A BiCMOS wireless interface chip for micromachined stimulating microprobes

This paper describes a BiCMOS interface chip, (Interestim-1), for wireless power and data transfer to the University of Michigan micromachined stimulating microprobes (STIM). Interestim-1 uses an amplitude modulated 4MHz carrier to receive data and power through inductive coupling. It is designed to generate dual regulated +/-5V supplies capable of providing up to 50mW, to regenerate a 4MHz internal clock from the radio-frequecny (RF) carrier, and to extract data bit stream up to 100kBit/sec from the ASK modulated RF carrier. The internal clock is stepped down by a user selectable ratio to be synchronized with the recovered data and sent to the STEM probes after parity checking, DC level shifting, and adding strobe pulses based on the STIM microprobe timing protocol [3]. The circuitry has been designed and fabricated in the University of Michigan's single metal, dual-poly 3-mum BiCMOS process, and has 1100 transistors occupying an area of 10mm(2) (Fig. 1). The total power dissipation of the chip when supplying 20mW to the stimulator chip is less than 10mNV.