An overview of the recent wideband transcutaneous wireless communication techniques

A 13.56-mbps pulse delay modulation based transceiver for simultaneous near-field data and power transmission

A fully-integrated near-field wireless transceiver has been presented for simultaneous data and power transmission across inductive links, which operates based on pulse delay modulation (PDM) technique. PDM is a low-power carrier-less modulation scheme that offers wide bandwidth along with robustness against strong power carrier interference, which makes it suitable for implantable neuroprosthetic devices, such as retinal implants. To transmit each bit, a pattern of narrow pulses are generated at the same frequency of the power carrier across the transmitter (Tx) data coil with specific time delays to initiate decaying ringing across the tuned receiver (Rx) data coil. This ringing shifts the zero-crossing times of the undesired power carrier interference on the Rx data coil, resulting in a phase shift between the signals across Rx power and data coils, from which the data bit stream can be recovered. A PDM transceiver prototype was fabricated in a 0.35- μm standard CMOS process, occupying 1.6 mm(2). The transceiver achieved a measured 13.56 Mbps data rate with a raw bit error rate (BER) of 4.3×10(-7) at 10 mm distance between figure-8 data coils, despite a signal-to-interference ratio (SIR) of -18.5 dB across the Rx data coil. At the same time, a class-D power amplifier, operating at 13.56 MHz, delivered 42 mW of regulated power across a separate pair of high-Q power coils, aligned with the data coils. The PDM data Tx and Rx power consumptions were 960 pJ/bit and 162 pJ/bit, respectively, at 1.8 V supply voltage.

Performance of a high-speed transcutaneous link with error correction coding

Several low-power communication strategies have been studied for interfacing with cortical implants via mutual inductance links. In this paper, we consider performance optimization strategies for a mutual-inductance link based on the Pulse Harmonic Modulation method. We consider two enhancements that may allow for increased throughput in the PHM system. First, a low-power error-correcting code is used to improve the system's robustness against noise, timing jitter and other non-ideal factors. Second, the system is adapted for multi-level modulation as a means of increasing the data rate. Our results characterize each systems' bit error rate as a function of pulse jitter, power interference and comparator offset.