| This work describes the first telemetry powered implantable microsystem to be fully integrated onto a single chip. This system is an 8-channel programmable neuromuscular stimulator for use with peripheral nerve electrodes. This implant receives all power and data through inductive coupling with an integrated, on-chip coil. Therefore, it requires no batteries or transcutaneous leads. Because it is fully integrated, this is one of the smallest wireless implantable stimulators ever developed.; The system's stimulating output is a biphasic current waveform with a programmable interphase delay. Each phase has a 5-bit programmable amplitude of up to 2 mA, and a 10-bit programmable duration of up to 2 ms. The system is capable of stimulation frequencies of over 150 Hz. Full scale stimulation can be obtained through loads of up to 1.7 k{dollar}Omega.{dollar} The system is powered by a 4 MHz carrier, and data is sent by pulse width encoded amplitude modulation.; The system's integrated circuitry is Bi-CMOS, contains 3,100 transistors, and measures 2.0 mm by 8.7 mm. It includes an RF receiver, a 4 Volt DC supply generator, a 500 kHz clock generator, data detection circuitry, finite state machine controlled logic, a 5-bit DAC output current source, and low resistance output switches. This circuitry was fabricated, tested, and is fully functional. It consumes 14.8 mW from the 4 Volt supply during full scale 2 mA stimulation.; Integrated on-chip coils optimized for inductive powering were developed as part of this work. These coils have electroplated copper windings, electroplated NiFe core, planar spiral design, and are CMOS compatible. Six different coil structures were fabricated, tested, and compared. A 2 by 10 mm, seventeen turn version of the best coil structure has an inductance of 2.9 {dollar}mu{dollar}H and receives over 20 mW DC at a distance of up to 3 cm from a 8-cm diameter planar transmitter coil. An analytical model for inductive powering using on-chip coils has been developed, and the design of the on-chip coils was optimized using this model. General design guidelines for on-chip coils have been devised which, together with the analytical model, can be used to quickly implement on-chip coils for inductively powering many different microsystems. |
