Intracortical brain computer interfaces hold the potential to revolutionize neurotherapeutics, but they must overcome technological challenges such as the high data rates generated by high-channel-count neural sensors and the stringent power and volume constraints of implantable devices. In addition, the brain-wide coverage needed for a deeper understanding of brain processes challenges the synchronization between distributed neural sensors and the central neural hub. To address these challenges, we present a deterministic-latency and power-efficient serializer–deserializer (SerDes) telemetry network that effectively mitigates the synchronization issue under strict power and volume constraints. The serializer on the sensor side employs event-based sampling and a packet-based address-event representation transmission protocol, achieving a low power consumption of only 127 µW and a low latency variation <10 µs. A crystal-free clock source is employed on the sensor side to minimize power consumption, with serialized data encoded using Manchester coding scheme. The deserializer on the hub handles the bit period uncertainty by counting and extracting the bit period of received data with a clock only ∼2.2× faster than the serializer clock. The proposed counting-based Manchester decoder achieves a wide frequency coverage up to 204 000 ppm of frequency variation. The deserializer achieves a measured Manchester decoding bit error rate (BER <10−6), with a total estimated power consumption below 415 µW. The SerDes performance has been validated with in vivo pre-recorded data, demonstrating a compression ratio greater than 7, while preserving a high signal fidelity with an average RMSE <6 µVRMS. ... Read more

A near-field galvanic coupled transdural telemetry ASICs for intracortical brain-computer interfaces is presented. The proposed design features a two channels transmitter and three channels receiver (2TX-3RX) topology, which introduces spatial diversity to effectively mitigate misalignments (both lateral and rotational) between the brain and the skull and recovers the path loss by 13 dB when the RX is in the worst-case blind spot. This spatial diversity also allows the presented telemetry to support the spatial division multiplexing required for a high-capacity multi-implant distributed network. It achieves a signal-to-interference ratio of 12 dB, even with the adjacent interference node placed only 8 mm away from the desired link. While consuming only 0.33 mW for each channel, the presented RX achieves a wide bandwidth of 360 MHz and a low input referred noise of 13.21 nV/√ H z. The presented telemetry achieves a 270 Mbps data rate with a BER < 10 −6 and an energy efficiency of 3.4 pJ/b and 3.7 pJ/b, respectively. The core footprint of the TX and RX modules is only 100 and 52 mm 2 , respectively, minimizing the invasiveness of the surgery. The proposed transdural telemetry system has been characterized ex-vivo with a 7-mm thick porcine tissue. ... Read more

In this paper, we propose a method to suppress supply pushing of an LC oscillator such that it may directly operate from a switched-mode dc-dc converter generating fairly large ripples. A ripple replication block (RRB) generates an amplified ripple replica at the gate terminal of the tail current source to stabilize the oscillator's tail current and thus its oscillating amplitude. The parasitic capacitance of the active devices and correspondingly the oscillation frequency are stabilized in turn. A calibration loop is also integrated on-chip to automatically set the optimum replication gain that minimizes the variation of the oscillation amplitude. A 4.9-5.6-GHz oscillator is realized in 40-nm CMOS and occupies 0.23 mm&#x00B2; while consuming 0.8-1.3 mW across the tuning range (TR). The supply pushing is improved to &lt;1 MHz/V resulting in a low &lt;-49-dBc spur due to 0.5-12-MHz sinusoidal supply ripples as large as 50 mVpp. We experimentally verify the effectiveness of the proposed technique also in face of saw-tooth, multi-tone, and modulated supply ripples. ... Read more