Self-impedance calibrated PVT-insensitive pseudo open drain output driver without external resistors

Proposed is a pseudo open drain output driver without external resistors. The resistance variation detector can reduce the cost and space of external resistors. The PVT variation detector is able to sense process, voltage and temperature conditions. The on-die termination impedance is constantly matched in response to the resistance, process, voltage and temperature conditions. The overall circuit occupies 0.126 mm² and consumes 5.58 mW, and the circuit is implemented in 0.18 m CMOS technology.