A non-contact interface for modular smartphones that can provide a data connection at a maximum MIPI rate of 6 Gb/s has been developed. A two-fold transmission line coupler, which is a small-size coupler that has a wide bandwidth, is proposed for modular smartphones, where the layout area is strictly limited. The coupler size is 6 mm2 for a 5 mm communication distance, which is 1/24 smaller than the conventional coupler. Since many wireless communication components, such as LTE, WiFi, and GPS transceivers, are assembled in a small module, the interference between the non-contact interface and the wireless transceivers should be suppressed. To improve noise immunity and reduce unwanted radiation from the coupler, an electromagnetic-compatibility robust pulse transceiver is proposed. A synchronous receiver using an edge counting clock recovery circuit improves noise immunity, and a bi-phase pulse transmitter reduces noise radiation in the GPS band. There is no EMS by LTE or WiFi signals on the data connection at BER < 10-12 when the coupler is separated by a distance of 2 mm and no EMI on GPS signals at a separation of 10 mm. Compared with the state-of-the-art result, the highest energy efficiency (6 pJ/b) and space efficiency (1.2mm2/1 mm distance) is achieved.
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