IMPEDANCE-CONTROLLED PSEUDO-OPEN DRAIN OUTPUT DRIVER

摘要

An impedance-controlled pseudo-open drain output driver is provided to minimize impedance matching an error generation while having short impedance fixing time, by excluding the usage of an external resistor. A PVT(Process, Voltage, Temperature) variation detection unit(100) comprises a delay line receiving a reference clock as an input, and detects state variation of the delay line according to process, voltage and temperature condition. A selection signal generation unit(200) generates a driving selection signal corresponding to a detection signal outputted from the PVT variation detection unit and output data. An output driving unit(300) drives an output stage by comprising a number of pullup/pulldown driving blocks controlled by the driving selection signal. Each pullup/pulldown driving block comprises a resistor corresponding to an expected impedance value.