A PIWM-FSK transmitter for implantable wireless neural recording microsystems

In this paper, a wireless telemetry unit for implantable neural recording microsystems is presented, which is designed based on pulse interval and width modulation. Variable-time coding nature of this technique leads to a reduction in symbol length of the coded signal, which consequently results in doubling the maximum possible data rate of the transmitter (in comparison with traditional pulse width modulation based transceivers). This allows for the expansion of the capacity (number of channels) of the neural recording implant by almost a factor of two. Based on the proposed idea, a transmitter is designed in a 0.18-µm standard CMOS technology. According to simulation results, the transmitter works with a data rate of 18.7 Mb/s and consumes 1.9 mW of power from a 1.8-V power supply.