A fully integrated 200 µW, 40pJ/b wireless transmitter for implanted medical devices and neural prostheses

In this paper we introduce a wireless transmitter suitable for implanted medical devices (IMDs) and neural prostheses. The transmitter achieves 500kbps data rate while consuming a peak power of 200 μW from a 1.2 V supply in a 130nm technology and has an active area of 35 μm by 45 μm. The transmitter works in the Medical Implant Communication Service (MICS) frequency band (401 - 406 MHz) and transmits the signal at a power of -20 dBm while achieves energy efficiency of 40pJ/b. The transmitter achieves this performance through a modified pulse position modulation called saturated analog signal (SAS) which has been tailored to reduce not only the peak and average power consumption but also helps reduces the number of elements required for signal generation and dispenses the need for a crystal which in turn minimizes the overall footprint of the transmitter. The transmitter can also dynamically trade off duty cycling and energy consumption with data rate and range requirements for better operability on a constantly changing environment due to the inherent flexibility of the modulation scheme.