A 12Gb/s non-contact interface with coupled transmission lines

The expanding capacity of today's memory cards and increasing speed of processors have created demands for high data rate interfaces between memory cards and processors. Compared to conventional contact pins, wireless interfaces have received tremendous interest for reasons of more convenience, higher reliability, and higher data rate. Two major types of near-field wireless communication techniques using capacitive coupling and inductive coupling channels have been investigated. Tens of Gb/s/ch is achieved using both methods with a communication distance of tens of microns in TCI (thru-chip-interface) applications [1-2]. However, when the communication distance denters the mm range in such applications as non-contact memory cards, the sizes of capacitors or inductors must be up scaled to detect enough electrical flux or magnetic flux, whose magnitude decay as 1/dⁿ (n>1). As a result, the self-resonance frequency f_SR is reduced significantly, which becomes the dominant limiting factor for the achievable data rate, since the maximum data rate is usually chosen as 1/2 or 1/3 of f_SR in order to avoid signal peaking [3]. Although multi-channel solutions are viable to increase the total data rate, complex systems are required to address the skew issues in synchronization, and low area efficiency is resulted to reduce crosstalk interferences as shown in Fig. 28.3.1.