| 摘要 |
PURPOSE: A power-up circuit of a semiconductor device is provided to prevent serious influence on a power-up sequence even in the case of a great change of the threshold voltage of a diode by using three n-channel metal-oxide-semiconductor(NMOS) diodes, and to stabilize the power-up sequence by guaranteeing an initial value when a power-up signal is set up. CONSTITUTION: The first NMOS diode(21) is connected between Vdd supply terminal and the first node. The second NMOS diode(22) maintains the voltage of the first node higher than a threshold voltage, connected between the first and second nodes. The third NMOS diode(23) uniformly maintains the voltages of the first and second nodes when the power-up sequence is finished, connected between the second node and a Vss supply terminal. The first NMOS transistor(24) is connected between the Vdd supply terminal and an aa node, and the gate of the first NMOS transistor is connected to the first node. The second NMOS transistor(25) determines the voltage level of a bb node, and the gate of the second NMOS transistor is connected to the aa node. A PMOS transistor(26) supplies a proper current to the bb node, connected between the bb node and the Vdd supply terminal. The first and second inverters(27,28) output a power-up sequence signal, connected in series to the bb node.
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