A 10Gb/s Digital Isolator Using Coupled Split-Ring Resonators with 24kVpk Surge Capability and 100kV/μS Common-Mode Transient Immunity

High speed data links play a key role in industrial and medical systems. Galvanic isolation in high-speed links ensures the safety of human operators and instruments. Opto-isolators generally achieve high voltage ratings but suffer from delay and reliability concerns [1]. A mm-wave isolator [2] using fiber can transmit 4Gb/s data but it adds system complexity. In contrast, magnetically and capacitively coupled digital isolators are a more compact solution. Conventional digital isolators can tolerate >10kV surge voltage and >50kV/μs common-mode transient (CMT) across a high-voltage-rated dielectric thin film [3 – 6]. However, their data rate is limited to 0.5Gb/s except for [4], which runs at 2.5Gb/s. To provide isolated solutions for protocols like USB3 and HDMI, isolator data rates must be increased to 10Gb/s. However, doing this in the presence of CMT strikes is challenging because CMT currents can couple through the parasitic capacitance across the thin isolation barrier. To maintain sufficient signal-to-noise ratio, large signal modulation schemes like on-off-keying (OOK) are needed, which require large bandwidths at high data-rates. Reducing the isolation distance usually increases bandwidth and efficiency at the cost of isolation capability. Increasing driver power can compensate for the isolator insertion loss at the risk of exceeding the FCC15 EMI limit. In this work, an integrated galvanic isolated data transceiver is presented. A split-ring resonator (SRR) based isolator, a transformer-based wideband matching network, and a duty-cycle-balancing control circuit have been employed. This digital isolator achieves a data transfer rate of 10Gb/s with deterministic jitter (DJ) of 10.9ps, while keeping the isolation capability of 100kV/μs common-mode transient immunity (CMTI) and 24kV surge rating.