A 1 Tbit/s Bandwidth 1024 b PLL/DLL-Less eDRAM PHY Using 0.3 V 0.105 mW/Gbps Low-Swing IO for CoWoS Application

A 1 Tbit/s bandwidth PHY is demonstrated through CoWoS™ platform. Two chips: SOC and embedded DRAM (eDRAM), have been fabricated in TSMC 40 nm CMOS technology and stacked on a silicon interposer chip. 1024 DQ buses operating at 1.1 Gbit/s with VDDQ = 0.3 V are proven between SOC chip and eDRAM chip in experimental results with 1 mm signal trace length on the silicon interposer. A novel timing compensation mechanism is presented to achieve a low-power and small area eDRAM PHY that excludes PLL/DLL but retains good timing margin. Another data sampling alignment training approach is employed to enhance timing robustness. A compact low-swing IO also achieves power efficiency of 0.105 mW/Gbps.