A Multi-Gbps, Energy Efficient, Contactless Data-Communication Link for Machine-to-Machine (M2M) Interaction with Rotational Freedom

This paper presents a low cost, compact, short-reach contactless data link designed for M2M applications requiring a full 360° rotational freedom. Full rotational freedom is enabled by a 16 GHz split-ring resonator (SRR) based near field coupler (NFC) which provides a fourth order bandpass characteristic with a 4 GHz bandwidth and ~2 dB insertion loss. The link employs 65 nm CMOS TX and RX chipsets for OOK modulation and demodulation of a 16 GHz carrier. The end-to-end contactless link is demonstrated with a variable gap (0.1 mm to 0.7 mm) and rotation angle (covering full range of 360°) between the TX and RX boards. Additionally, a BER <1E-12 is demonstrated up to 2.6 Gbps over 0.5 mm gap and with a full 360° rotation capability and a 50 mW power consumption, leading to a competitive energy efficiency of ~20 pJ/bit. This work demonstrates for the first time viability of robust, low-cost, mass manufacturable, energy efficient >2Gbps (BER <1E-12) rotational links operating at cm-wave frequencies without any signal conditioning.