US 6,756,834 B1 · Direct power-to-ground ESD protection with an electrostatic common-discharge line

Abstract

ESD protection is provided by local ESD-protection devices between each pad and a common-discharge line (CDL). Each ESD-protection device has p-well or p-substrate taps to a local ground rather than to the CDL, reducing noise coupling from the I/O's through the CDL. Another ESD clamp that bypasses the CDL is provided between each pair of internal power and ground buses. Better protection of core circuits during power-to-ground ESD events is provided by bypassing the CDL since only one ESD clamp rather than two ESD-protection devices must turn on. The ESD clamps and ESD-protection devices can be gate-coupled n-channel transistors with coupling capacitors between the pad and the transistor gate. Devices can also be substrate-triggered transistors or active ESD clamps that include an inverter between a coupling capacitor to the CDL and the n-channel transistor gate.

Claims20

Dependent claims

An electro-static-discharge (ESD) protected integrated circuit comprising:

first core circuitry connected between a first power bus connected to a first power pad and a first ground bus connected to a first ground pad;
second circuitry connected between a second power bus connected to a second power pad and a second ground bus connected to a second ground pad;
a common-discharge line that is not directly connected to power or ground;
a plurality of indirect ESD-protection devices coupled to the common-discharge line, each indirect ESD-protection device coupled to conduct ESD current between a pad and the common-discharge line;
and
a first direct ESD clamp between the first power bus and the first ground bus, for bypassing the common-discharge line and directly conducting ESD current from the first power bus to the first ground bus when an ESD pulse is applied between the first power pad and the first ground pad, whereby ESD current is conducted through two of the plurality of indirect ESD-protection devices and the common-discharge line, or bypassing the common-discharge line through the first direct ESD clamp.

3 more elements

An electro-static-discharge (ESD) protection circuit comprising:

a common-discharge line;
a plurality of external signal pads;
a first power pad and a second power pad;
a first ground pad and a second ground pad;
a first direct power-ground clamp that comprises:
a direct capacitor connected between the first power pad and a direct-gate node;
a direct n-channel transistor having a drain connected to the first power pad,
a source connected to the first ground pad, and a gate connected to the direct-gate node;
a direct resistor for discharging the direct capacitor, the direct resistor having a terminal connected to the direct-gate node;
a plurality of protection devices coupled between the plurality of external signal pads and the common-discharge line, wherein each protection device between a protected pad and the common-discharge line comprises:
a coupling capacitor connected between the protected pad and a coupled-gate node;
a conducting n-channel transistor having a drain connected to the protected pad, a source connected to the common-discharge line, and a gate connected to the coupled-gate node;
a discharge resistor for discharging the coupling capacitor, the discharge resistor having a terminal connected to the coupled-gate node.

10 more elements

An integrated circuit comprising:

common-discharge line means for discharging electro-static-discharges between pads of the integrated circuit;
a plurality of input/output I/O pads;
a first power pad and a second power pad;
a first ground pad and a second ground pad;
first active-clamp means, between the first power pad and the common-discharge line means, for conducting electro-static-discharges from the first power pad to the common-discharge line means;
second active-clamp means, between the second power pad and the common-discharge line means, for conducting electro-static-discharges from the second power pad to the common-discharge line means;
first gate-coupled device means, between a first I/O pad in the plurality of I/O pads and the common-discharge line means, for conducting electro-static-discharges from the first I/O pad to the common-discharge line means;
second gate-coupled device means, between a second I/O pad in the plurality of I/O pads and the common-discharge line means, for conducting electro-static-discharges from the second I/O pad to the common-discharge line means;
third gate-coupled device means, between a third I/O pad in the plurality of I/O pads and the common-discharge line means, for conducting electro-static-discharges from the third I/O pad to the common-discharge line means;
first ground gate-coupled device means, between the first ground pad and the common-discharge line means, for conducting electro-static-discharges between the first ground pad to the common-discharge line means:
second ground gate-coupled device means, between the second ground pad and the common-discharge line means, for conducting electro-static-discharges between the second ground pad to the common-discharge line means.

8 more elements

Dependencies are inferred from the claim text.

Direct power-to-ground ESD protection with an electrostatic common-discharge line

Life of this patent

Direct power-to-ground ESD protection with an electrostatic common-discharge line

Life of this patent

Abstract

Claims20