A 250Mbps 24pJ/bit UWB-inspired optical communication system for bioimplants

Abstract

This paper presents an optical communication system, implementing a UWB-inspired pulsed coding technique, for emerging high throughput bio-applications such as brain machine interfaces. The proposed solution employs sub-nanosecond laser pulses that, compared to the state-of-the-art, allows for high bit rate transmissions and reduced power consumption. The overall architecture consist of a transmitter and receiver that employ a pulsed semiconductor laser and a small sensitive area photodiode. This can allow for CMOS integration into a compact silicon footprint (estimated lower than 1 mm 2 in a 0.18 µm technology). The analogue circuits presented herein have been implemented using discrete off-the-shelf components. These provide the bias and drive signals for laser pulse generation, photodiode signal detection and conditioning. Moreover, the digital subsystem for data coding and decoding processes have been implemented on a FPGA board through VHDL description language. Experimental results validate the overall functionality of the proposed system using a diffuser between transmitter and receiver to emulate skin/tissue. This shows the capability of operating at bit rates up to 250 Mbps achieving BER less than 10 −9 and power efficiency as low as 24 pJ/bit. These results enable, for example, the transmission of a 1000-channel neural recording system sampled at 16kHz with 16-bit resolution.

A 300 Mbps 37 pJ/bit UWB-Based Transcutaneous Optical Biotelemetry Link

“…These innovations increase the achievable data rate compared to the state-ofthe-art whilst minimising BER and power consumption. This paper extends the preliminary work reported in [49] providing additional technical detail (design implementation, results, analysis) and experimental data using biological tissue.…”

“…The work presented herein describes a high bandwidth optical telemetry that employs a specific pulsed data coding technique using sub-nanosecond laser pulses. This builds on our previous work [48], [49], by improving: (i) the front-end analog (laser drive and photodiode interface) circuit performance (bandwidth, power consumption); and (ii) the digital circuits (encoding, decoding, processing) capability using high performance reconfigurable logic (FPGA). These innovations increase the achievable data rate compared to the state-ofthe-art whilst minimising BER and power consumption.…”

“…Optical telemetries have thus been developed that utilise near infra-red (NIR) wavelengths (i.e. >800 nm) [16], [44]- [49]. These systems typically employ a semiconductor laser for transmission, and a photodiode (PD) for receiving the data.…”

An Ultra-Wideband-Inspired System-on-Chip for an Optical Bidirectional Transcutaneous Biotelemetry

“…The transmitter uses a pulse width (i.e., for CURRENT PULSES) of 300 ps with minimum and maximum current levels of approximately 1 mA and 25 mA, respectively (for driving the LD). On the other hand, the receiver takes a CURRENT PULSE input signal of about 70 µA (emulating the expected PD photocurrent based on our previous measurements [7], [11]). It is important to observe also that the recovered clock signal presents a duty-cycle of about 70% which, if required, could be suitably compensated by a duty-cycle correction circuit [13].…”

“…These approaches however tend to increase the laser/emitter response time and the signal-to-noise ratio thus limiting the system bandwidth and the maximum achievable data rate up to 100 Mbps with a power efficiency of 21 pJ/bit [2], [8], [10]. Recently, we have demonstrated an UWB-inspired optical wireless biotelemetry system implemented using commercial off-the-shelf components that is able to overcome these limitations reaching data rate up to 250 Mbps and 24 pJ/bit power efficiency [11].…”