1.2Gb/s 3.9pJ/b mono-phase pulse-modulation inductive-coupling transceiver for mm-range board-to-board communication

Recently, short distance board-to-board interconnections are widely employed in portable systems and wearable devices to accommodate many components into an extremely tight footprint. In particular, portable devices such as smart phone and tablet require over 1Gb/s data transfer through ~1mm distance between AP board and a high resolution wide screen display board. Most of display interfaces are implemented with wire-line F-PCB connector, but, they suffer from: 1) high manufacturing cost, 2) the large form factor of the connector and standard socket and 3) large capacitance values of the connector and socket degrading the channel characteristics. So far, various communication interfaces have been tried to realize low cost, small form factor and low energy operation, but with limited success. The bi-phase pule modulation was used in board-to-board communication rather than base-band transmission due to its low energy operation [1-5]. This method used the positive pulse current for data `1' and the negative pulse current for data `0', and the receiver recovered the data by sampling the data at the exact time, which requires an accurate delay control unit. However, the bi-phase pulse modulation consumes significant power because: 1) current pulses sampled at every data consume large current in TX, and 2) a power hungry delay control unit is required to exactly control the sampling time.