A resistor-free 4.266 Gbps LPDDR4 I/O in 10 nm FinFET CMOS technology

This paper presents a 4.266 Gbps LPDDR4 I/O with resistor-free on-die termination (ODT). The resistor-free ODT utilizes resistor-free driving unit (RFDU) with adaptive bias unit (ABU). The ABU adopts source-follower based structure which provides an adaptive bias voltage to compensate the saturated ID current caused non-linearity. The proposed LPDDR4 I/O is fabricated in 10 nm FinFET technology with the post-driver area of 0.0025mm². The measurement result shows that the calibrated ODT resistances among 63 dies all meet LPDDR4 specifications. Furthermore, the eye opening of 0.73 UI is achieved with 4.266 Gbps PRBS pattern.