InP HEMT amplifier design and packaging techniques for multi-10-Gbps data reception in sub-millimeter-wave bands

This paper reports circuit design and packaging techniques for multi-ten gigabit per second (Gbps) data reception in sub-millimeter-wave bands, aiming at short-range wireless communications. A common-gate (CG) amplifier with shielded signal pads for flip-chip (FC) mounting was developed in 75-nm Indium Phosphide high electron mobility transistor (InP HEMT) technology. The CG amplifier exhibited a small-signal gain of more than 20 dB at 300 GHz and a 3-dB bandwidth of more than 30 GHz, which are sufficient to receive 20 Gbps data. To realize a low-loss and compact receiver module, FC packaging rather than face-up packaging were chosen from a point of stable signal propagation in a chip while keeping mechanical strength. Materials for print circuit board (PCB) and process rules, particularly minimum size and spacing with regard to through vias, are considered. As a result, our FC packaging technique using polyimide PCBs is found to be available up to 400 GHz.