Low-power BPSK inductive data link for an implanted intracortical visual prosthesis

In making visually impaired people see again, for most cases the only option is to stimulate the visual cortex. In building such a system, it is desired that the communication to/from the implant and powering be done wirelessly to avoid infections. For the downlink, which is sending stimulation data to the implanted electrode, bandpass-sampled binary phase shift keying (BPSK) is chosen due to its potential for low-power consumption at its digital receiver. However, since an inductive link is most suited, designing practical inductive links with a flat band region to avoid poor phase transition and also refining the reset timing for imperfect transition times as well as designing low-power custom 1- bit Analog-to-digital converter is crucial. The bandpass-sampled BPSK system is designed and simulated at circuit level in Cadence using 180 nm CMOS technology at data rates of 0.5-4 Mbps and carrier frequency of 5-12 MHz. The improved bandpass-sampled BPSK system meets the requirements on data-rate, low-power consumption and robustness and is an integral part of the overall wireless communication and powering of the implanted intracortical visual prosthesis.