The contact-less method of chip-to-chip high speed data transmission monitoring

Abstract

This paper presents a technique of decoupling differential signals transmitted in a pair of microstrip lines on a printed circuit board (PCB), using dedicated coupler for high speed data transmission monitoring in chip-to-chip interconnections. The coupler used for signal probing is overlayed on the pair of microstrip lines under test, and provides a signal to the next blocks of the measurement system without disturbing transmission in the lines. Starting from the basic configuration obtained in the previous work, we describe a procedure of re-designing the coupler for enhanced directivity so that it is suitable for high-speed data transmission monitoring. The new coupler structure has improved topology based on stepped-impedance resonators with geometry parameters adjusted using numerical optimization techniques. The correctness of the design has been confirmed by the time-domain measurements performed for real chip-to-chip communication signals, using a dedicated measurement system based on Xilinx Virtex-6 FPGA Development Kit. The presented technology can be used for reducing the cost of the product diagnostics by eliminating dedicated measurement connectors, run-time system debugging or reverse engineering.