ELECTROSTATIC DISCHARGE PROTECTIVE CIRCUIT

摘要

PURPOSE: An electrostatic discharge(ESD) protective circuit is provided to minimize variation of a gate voltage depending on ESD voltage and frequency and thereby to improve the protective characteristics. CONSTITUTION: An electrostatic discharge protective circuit includes a first transistor(21) which is connected to an input pad(20) to discharge ESD charges, a capacitor(22) and a diode(23) which are connected to the input pad(20) to enhance bipolar driving capacity of the first transistor(21) by applying a gate voltage to a gate of the first transistor(21) when the ESD charges are supplied, a second transistor(24) a drain of which is connected between the capacitor(22) and the diode(23) to control the driving of the first transistor(21) during the operation of a chip, and a resistor(25) which delays the transmission of the ESD charges to internal circuits when the ESD charges are supplied to the input pad(20). The gate voltage of the first transistor(21) is maintained by the control of both the capacitor(22) and the diode(23) regardless of ESD voltage and frequency.