An Inside Body Power and Bidirectional Data Transfer IC Module Pair

An IC module pair utilizing only three wires was designed for biomedical implants with a master unit (MU) and a small, lightweight satellite unit (SU). Power was delivered from the MU to the SU using a three-phase signal and converted to dc in the SU IC module by a passive MOS ac-dc converter. Bidirectional data transfer between the two units was achieved by modulating the amplitudes (at periods that do not affect power delivery) and the positions of the rising and falling edges of the three-phase signal. A bidirectional data rate in the range of MB/s and an overall power efficiency of 90.2% for a 2.84-mW load were achieved in a 0.18-mu m CMOS process.