Patent ID: 7221199

Claim:
A power up reset circuit comprising: a power supply voltage follower connected to a power supply for proportionally following an increase of a supply voltage to output a pull-up control signal; and a pulse generation control circuit coupled to an output node of the power supply voltage follower and the power supply for outputting a power up reset signal in response to the pull-up control signal, when the supply voltage begins ramping up, the pulse generation control circuit comprising: a first MOS transistor comprising a first gate, a first node and a second node, the first node being coupled to ground; a second MOS transistor comprising a second gate, a third node and a fourth node, the third node of the second MOS transistor being coupled to the first gate of the first MOS transistor; and a third MOS transistor comprising a third gate, a fifth node and a sixth node, the third gate being coupled to the output node of the power supply voltage follower, the fifth node being coupled to the fourth node, the sixth node being coupled to the power supply, wherein the pulse generation control circuit switches a voltage level at the output node, when the supply voltage exceeds a predefined threshold voltage, thereby causing the power up reset signal to produce a reset pulse.