US5521783A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrostatic discharge protection circuit
Assignee: Analog Devices Inc
•
Filing: 1993-09-17
•
Granted: 1996-05-28
•
Expires: 2013-09-17
Abstract
Abstract An electrostatic discharge (ESD) protection circuit formed on a semiconductor substrate includes a first stage clamping circuit and a second stage clamping circuit separated by a dissipative circuit. The first and second stage clamping circuits are designed to absorb and dissipate the high and low energy ESD, respectively. The first clamping circuit has a self-regulated current mechanism capable of diverting the electrical current generated by an ESD from a high current density region to a low current density region within the semiconductor substrate, and simultaneously lowers the ESD induced voltage for safe protection.
Inventors
- 👤 Edward L. Wolfe
- 👤 Andrew H. Olney
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 04:46
CPC Classifications
H; H10; H10D; H10D89/00; H10D89/60; H10D89/601; H10D89/811; H10W; H10W72/00; H10W72/90; H10W72/50; H10W72/531; H10W72/536; H10W72/541; H10W72/547; H10W72/5473; H10W72/59; H10W72/931; H10W72/932
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
220 words
An electrostatic discharge protection circuit formed on a semiconductor substrate having an active circuit to be protected, a conductive element that is subject to the receipt of electrostatic discharge, a first power supply conductor and a second power supply conductor, said protection circuit comprising: a first clamping circuit electrically connected to the conductive element, said first clamping circuit comprising a bipolar transistor having a collector-emitter circuit connected between said conductive element and said second power supply conductor, and a resistive base connected in common with its emitter, said bipolar transistor having a breakdown conduction mode with a primary breakdown current conduction path through its base and an active conduction mode with a primary active current conduction path that is substantially more subsurface in said substrate than said primary breakdown current conduction path, said bipolar transistor responding to an electrostatic discharge at said conductive element in excess of a predetermined limit by entering its breakdown conduction mode and conducting a primary breakdown current sufficient to generate a base voltage differential that triggers said transistor into its active conduction mode, said bipolar transistor during its active conduction mode clamping said conductive element at a voltage that is referenced to said second power supply conductor; and a second clamping circuit electrically connected between said first clamping and the active circuit to be protected.
Claim 2
Dependent Claim
220 words
An electrostatic discharge protection circuit formed on a semiconductor substrate having an active circuit to be protected, a conductive element that is subject to the receipt of electrostatic discharge, a first power supply conductor and a second power supply conductor, said protection circuit comprising: a first clamping circuit electrically connected to the conductive element, said first clamping circuit comprising a bipolar transistor having a collector-emitter circuit connected between said conductive element and said second power supply conductor, and a resistive base connected in common with its emitter, said bipolar transistor having a breakdown conduction mode with a primary breakdown current conduction path through its base and an active conduction mode with a primary active current conduction path that is substantially more subsurface in said substrate than said primary breakdown current conduction path, said bipolar transistor responding to an electrostatic discharge at said conductive element in excess of a predetermined limit by entering its breakdown conduction mode and conducting a primary breakdown current sufficient to generate a base voltage differential that triggers said transistor into its active conduction mode, said bipolar transistor during its active conduction mode clamping said conductive element at a voltage that is referenced to said second power supply conductor; and a second clamping circuit electrically connected between said first clamping and the active circuit to be protected.
Claim 3
Dependent Claim
48 words
The electrostatic discharge circuit as set forth in claim 1 wherein the collector of said bipolar transistor is connected to said conductive element and its emitter, base and collector establish a portion of said active current conduction path as a generally vertical path that extends below said base.
Claim 4
Dependent Claim
44 words
The electrostatic discharge protection circuit as set forth in claim 1, wherein said primary breakdown current generates an ohmic voltage potential across the bipolar transistor's base sufficient to trigger said bipolar transistor to switch from said breakdown conduction mode to said active conduction mode.
Claim 5
Dependent Claim
30 words
The electrostatic discharge protection circuit as set forth in claim 1 wherein said second clamping circuit comprises a MOS transistor having a substantially lower breakdown voltage than said bipolar transistor.
Claim 6
Dependent Claim
26 words
The electrostatic discharge protection circuit as set forth in claim 4, further comprising a voltage drop circuit electrically connected between said first and second clamping circuits.
Claim 7
Dependent Claim
24 words
The electrostatic discharge protection circuit as set forth in claim 5 wherein said dissipative circuit comprises an elongated buried layer underneath said breakdown transistor.
Claim 8
Dependent Claim
22 words
The electrostatic discharge protection circuit as set forth in claim 5 wherein said dissipative circuit comprises a resistor on said semiconductor substrate.
Claim 9
Dependent Claim
18 words
The electrostatic discharge protection circuit as set forth in claim 7 wherein said resistor is a polysilicon resistor.
Claim 10
Dependent Claim
25 words
The electrostatic discharge protection circuit as set forth in claim 1 wherein said second clamping circuit is electrically connected to said second power supply conductor.
Claim 11
Dependent Claim
44 words
The electrostatic discharge protection circuit as set forth in claim 9 further comprising: a third clamping circuit electrically connected to the input of said active circuit to be protected, and further electrically connected between said first power supply conductor and said second clamping circuit.
Claim 12
Dependent Claim
20 words
The electrostatic discharge protection circuit as set forth in claim 10 wherein said third clamping circuit comprises a MOS transistor.
Claim 13
Dependent Claim
58 words
The electrostatic discharge protection circuit as set forth in claim 11 wherein said MOS transistor comprises a p-type channel, a gate, a drain and a source, with said gate and said source being electrically connected to said first power supply connector and with said drain being electrically connected to the input of said active circuit to be protected.
Claim 14
Dependent Claim
43 words
The electrostatic discharge protection circuit as set forth in claim 11 further comprising: a fourth clamping circuit electrically connected between said wire-bonding pad and said third clamping circuit, and further electrically connected between said first power supply conductor and said first clamping circuit.
Claim 15
Dependent Claim
35 words
The electrostatic discharge protection circuit as set forth in claim 13 wherein said fourth clamping circuit comprises a bipolar transistor having electrical characteristics substantially the same as the bipolar transistor in said first clamping circuit.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-05-28 | 1999-11-27 | 2000-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-05-28 | 2003-11-27 | 2004-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-05-28 | 2007-11-27 | 2008-05-28 | $7700.00 | Window Closed / Lapsed |