Time Interleaved Self-Synchronized Impulse-Radio Transceiver for Seamless Duplex Communication in Neural Implants

This paper introduces a time interleaving technique for impulse radio (IR) transceivers to enable seamless duplex communication in the uplink (UL) and downlink (DL) of neural implant interfaces. An integrated time interleaved (TI) transceiver prototype in CMOS process is presented, utilizing the idle time between received DL return-to-zero (RZ) bit sequences to insert the UL transmitter (TX) data without interfering the receiver (RX) operation. The crystal-free transceiver is synchronized with an external unit by a clock and data recovery (CDR) circuit that retrieves the implant system clock from the received radio frequency (RF) signal. The TI data link supports seamless duplex communication with the data transmission rates of 297 Mbps in the UL and 11 Mbps in the DL at 85 cm range with BER $\lt 10^{\mathbf {-4}}$ . The RX sensitivity and the TX output power are -54 dBm and -16.3 dBm, respectively. By effectively eliminating self-interference (SI) without the need for an external duplexer, this work improves the communication range by more than 5 times compared to frequency division duplexing (FDD) radios commonly used in medical implants.