Short-Range Quality-Factor Modulation (SQuirM) for Low Power High Speed Inductive Data Transfer

Wireless data telemetry for implantable medical devices (IMDs) has, in general, been limited to a few Mbps, and used for applications such as transmitting recordings from an implanted monitoring device, or uploading commands to an implanted stimulator. However, modern neural interfaces need to record high resolution potentials from hundreds of neurons; this requires much higher data rates. While fast wireless communication is possible using existing standards such as WiFi, power consumption demands are far too high for IMDs. Short range inductive link based telemetry, in particular impulse-based systems such as pulse-harmonic modulation (PHM), have demonstrated transfer speeds of up to 20 Mbps with a small power budget. However, these systems require complex and precise circuits, making them potentially susceptible to inter-symbol-interference. This work presents a new method named Short-range Quality-factor Modulation (SQuirM), which retains the low power consumption and high data rate of PHM, while improving the resilience of the system and simplifying the circuit design. Transmitter and receiver circuits were fabricated using 0.35 μm CMOS. The circuits were capable of reliably transceiving data at speeds of up to 50.4 Mbps, with a BER of <; 4.5×10
^-10
, and a transmitter energy consumption of 8.11 pJ/b.