EOS/ESD Protection circuit for an integrated circuit with operating/test voltages exceeding power supply rail voltages
First Claim
1. An electrical overstress protection circuit for protecting an active circuit from electrical overstress, the electrical overstress protection circuit having first and second inputs for respectively receiving first and second reference voltages, first and second outputs for respectively providing the first and second reference voltages to the active circuit, first and second signal pads for respectively connecting to an external circuit and the active circuit, the electrical overstress protection circuit comprising:
- first and second clamping circuits series connected between the first input and the first signal pad of the electrical overstress protection circuit, the first clamping circuit including a breakdown device that is constructed and arranged to conduct current in a first direction when a voltage across the breakdown device exceeds a forward conduction threshold, the second clamping circuit including a breakdown device constructed and arranged such that in a first direction of current through the breakdown device, the breakdown device has an active mode of operation and a breakdown mode of operation, the breakdown mode of operation occurring when a voltage across the breakdown device exceeds a reverse breakdown threshold, the breakdown device switching from breakdown mode to active mode when a magnitude of current through the breakdown device in the first direction exceeds a current threshold level; and
third and fourth clamping circuits series connected between the first output and the second signal pad of the electrical overstress protection circuit.
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Accused Products
Abstract
An electrical overstress (EOS) protection circuit for protecting an active circuit of an integrated circuit including first and second clamping circuits series connected between a first input and a first input/output of the EOS protection circuit and third and fourth clamping circuits connected between a first output of the protection circuit and a second input/output. In embodiments of the present invention an EOS protection circuit provides protection for an active circuit while enabling a voltage at an input pad to the active circuit to exceed a power supply reference by more than several volts and to be less than a ground reference by more than several volts.
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Citations
36 Claims
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1. An electrical overstress protection circuit for protecting an active circuit from electrical overstress, the electrical overstress protection circuit having first and second inputs for respectively receiving first and second reference voltages, first and second outputs for respectively providing the first and second reference voltages to the active circuit, first and second signal pads for respectively connecting to an external circuit and the active circuit, the electrical overstress protection circuit comprising:
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first and second clamping circuits series connected between the first input and the first signal pad of the electrical overstress protection circuit, the first clamping circuit including a breakdown device that is constructed and arranged to conduct current in a first direction when a voltage across the breakdown device exceeds a forward conduction threshold, the second clamping circuit including a breakdown device constructed and arranged such that in a first direction of current through the breakdown device, the breakdown device has an active mode of operation and a breakdown mode of operation, the breakdown mode of operation occurring when a voltage across the breakdown device exceeds a reverse breakdown threshold, the breakdown device switching from breakdown mode to active mode when a magnitude of current through the breakdown device in the first direction exceeds a current threshold level; and third and fourth clamping circuits series connected between the first output and the second signal pad of the electrical overstress protection circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. An electrical overstress protection circuit for protecting an active circuit from electrical overstress, the electrical overstress protection circuit comprising:
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first and second inputs for receiving first and second reference voltages of the active circuit; first and second outputs for providing the first and second reference voltages to the active circuit; first and second signal pads for respectively connecting to an external circuit and the active circuit; and first means for protecting the active circuit from an electrical overstress voltage at the first input having one of a positive or negative polarity with respect to the first signal pad, the first means for protecting having an off mode in which the first means for protecting has substantially no effect on the operation of the active circuit, and an on mode in which the first means for protecting limits an absolute value of a voltage at the first output with respect to the second signal pad to less than a predetermined clamping voltage value, the first means for protecting including switching means for switching from the off mode to the on mode when an absolute value of an electrical overstress voltage at the first input with respect to the first signal pad exceeds a first threshold value, the first threshold value being greater than the first reference voltage value by at least approximately two volts. - View Dependent Claims (36)
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Specification