Input interface circuit

Abstract

The invention discloses an input interface circuit comprising an ESD (electro-static discharge) protection circuit, a waveshaping circuit, a well resistor circuit, an internal protection circuit and a buffer circuit. The ESD protection circuit includes a main ESD protection circuit and an auxiliary ESD protection circuit and prevents a chip from the damage made by external electrostatic discharge. The waveshaping circuit is composed of a Schmidt circuit and a buffer and connected with the ESD protection circuit. The Schmidt circuit is powered by an input PAD and used for shaping input signals. The well resistor circuit is connected with the waveshaping circuit and used for preventing an attacker from adding signals into the chip. The internal protection circuit is connected with the well resistor circuit and used for preventing voltage, caused during scribing, against damaging a circuit in the chip and allowing an output end of the input interface circuit outputting fixed low level as a resistor is cut off. The buffer circuit is connected with the internal protection circuit and used for strengthening drive capability of an input interface. The input interface circuit has the advantages that anti-attacking capability of the chip is remarkably improved, and accordingly the circuit in the chip is protected from damage of the attacker through the input PAD.

Description

technical field [0001] The invention relates to the field of I / O interface circuits, in particular to an input interface circuit. Background technique [0002] With the rapid development of integrated circuit technology, chips are widely used in various industries, and chips used in the field of financial security put forward higher requirements for chip security. [0003] For chips with a higher security level, designers should not only care about the chip's security algorithm module but also the chip's interface. The interface circuit is directly connected to the outside world, so it is most vulnerable to attacks. Attackers can attack the chip through the I / O interface without destroying the chip. [0004] see figure 1 As shown, the traditional input interface circuit is composed of ESD protection circuit, Schmidt circuit and buffer circuit. [0005] The ESD protection circuit is an electrostatic discharge protection circuit, which can solve most of the electrostatic di...

AI Technical Summary

Problems solved by technology

[0009] Traditional input interface circuits are not resistant to attacks

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