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

Abstract

A 1 Tbit/ s bandwidth PHY is demonstrated through CoWoS(TM) 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.