EP0149065A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
A protection clamp circuit for use in a monolithic circuit which inhibits current transients
Assignee: Motorola Solutions Inc
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Filing: 1984-11-24
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Granted: —
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Expires: 2004-11-24
Abstract
Abstract First and second Schottky diodes are formed in a respective first and second isolated epitaxial (epi) regions of a monolithic integrated circuit to inhibit current spikes that may otherwise occur as the monolithic circuit is inserted or removed from a "hot" socket having both an input signal and an operating potential supplied thereto. The monolithic circuit includes a floating resistor formed in a first isolated epi region which is connected between the input of the monolithic circuit to which the input signal is supplied and the base of a transistor. The transistor is formed in a third epi region which is isolated from both the first and second epi regions. The second epi region, which may contain one or more circuit elements, is contacted to the operating potential. The Schottky diodes provide clamping across the base-emitter junctions of two parasitic transistors which form a SCR that can be rendered conductive by the substrate not being grounded. The SCR is inhibited from being turned on by the two Schottky clamping diodes.
Inventors
- 👤 Paul Jackson Daniels
- 👤 Michael Edward Stanley
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 09:07
CPC Classifications
H; H10; H10D; H10D89/00; H10D89/60; H03; H03K; H03K17/00; H03K17/08; H03K17/081; H03K17/0812; H03K17/08126; H10D84/00; H10D84/60; H10D84/611; H10D84/613
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
239 words
In a monolithic integrated circuit formed by a substrate (50) of a first semiconductor material of a first conductivity type, an epitaxial layer (52) of a second semiconductor material of a second conductivity type, a plurality of regions (60, 62) of a semiconductor material of the first conductivity type formed in the circuit for isolating predetermined regions of the epitaxial layer from other of such epitaxial regions, and including at least one transistor (26) formed in a first one of the isolated epitaxial regions and a resistor (40) formed in a second one (64) of the isolated regions, conducting means (74) for connecting the resistor between a first terminal at which is intended to be supplied an input signal and a first circuit node, and means for supplying an operating potential to the circuit, a protection circuit for inhibiting current transients that can otherwise occur when the substrate is not maintained at a fixed reference potential when the input signal and the operating potential are simultaneously applied to the circuit, comprising: , a first Schottky diode (88) formed in the second one of the isolated epitaxial regions; and a second Schottky diode (90) formed in a third one of the isolated epitaxial region such that said first and second Schottky diodes inhibit turn on of any parasitic device that may be formed between the resistor and said third isolated epitaxial region through the substrate to inhibit the current transients.
Claim 2
Dependent Claim
239 words
In a monolithic integrated circuit formed by a substrate (50) of a first semiconductor material of a first conductivity type, an epitaxial layer (52) of a second semiconductor material of a second conductivity type, a plurality of regions (60, 62) of a semiconductor material of the first conductivity type formed in the circuit for isolating predetermined regions of the epitaxial layer from other of such epitaxial regions, and including at least one transistor (26) formed in a first one of the isolated epitaxial regions and a resistor (40) formed in a second one (64) of the isolated regions, conducting means (74) for connecting the resistor between a first terminal at which is intended to be supplied an input signal and a first circuit node, and means for supplying an operating potential to the circuit, a protection circuit for inhibiting current transients that can otherwise occur when the substrate is not maintained at a fixed reference potential when the input signal and the operating potential are simultaneously applied to the circuit, comprising: , a first Schottky diode (88) formed in the second one of the isolated epitaxial regions; and a second Schottky diode (90) formed in a third one of the isolated epitaxial region such that said first and second Schottky diodes inhibit turn on of any parasitic device that may be formed between the resistor and said third isolated epitaxial region through the substrate to inhibit the current transients.
Claim 3
Dependent Claim
212 words
In a monolithic integrated line receiver circuit (10) including a floating resistor (40) formed in a first epitaxial region (64) thereof, a second epitaxial region -(66) which is isolated from the first epitaxial region, means for connecting (74, 78) one end of the resistor to a first external terminal and connecting the second epitaxial region to a second external terminal at which are supplied an input signal (V 1 ) and an operating potential (V cc ) respectively, an amplifier stage (26) formed in a third epitaxial region which is isolated from both the first and second epitaxial regions, the amplifier stage being connected to the other end of the resistor, a protection circuit for inhibiting current transients that otherwise may occur if the substrate of the line receiver circuit is not grounded when both the input signal and the operating potential are simultaneously applied thereto due to a parasitic device (12) being rendered conductive, the parasitic device being formed between the resistor, the first epitaxial region, and the second epitaxial region through the substrate, comprising: a first Schottky diode (88) formed in the first epitaxial region; and a second Schottky diode (90) formed in the second epitaxial region, said first and second Schottky diodes inhibiting turn on of the parasitic device.
Claim 4
Dependent Claim
212 words
In a monolithic integrated line receiver circuit (10) including a floating resistor (40) formed in a first epitaxial region (64) thereof, a second epitaxial region -(66) which is isolated from the first epitaxial region, means for connecting (74, 78) one end of the resistor to a first external terminal and connecting the second epitaxial region to a second external terminal at which are supplied an input signal (V 1 ) and an operating potential (V cc ) respectively, an amplifier stage (26) formed in a third epitaxial region which is isolated from both the first and second epitaxial regions, the amplifier stage being connected to the other end of the resistor, a protection circuit for inhibiting current transients that otherwise may occur if the substrate of the line receiver circuit is not grounded when both the input signal and the operating potential are simultaneously applied thereto due to a parasitic device (12) being rendered conductive, the parasitic device being formed between the resistor, the first epitaxial region, and the second epitaxial region through the substrate, comprising: a first Schottky diode (88) formed in the first epitaxial region; and a second Schottky diode (90) formed in the second epitaxial region, said first and second Schottky diodes inhibiting turn on of the parasitic device.
Claim 5
Dependent Claim
215 words
A monolithic integrated circuit including a substrate (50) of a first conductivity semiconductor material, an epitaxial layer (52) of a second conductivity semiconductor material disposed on the substrate, a plurality of isolating regions (60, 62) of said first conductivity semiconductor material formed through the epitaxial layer in contact with the substrate which produce a plurality of separate isolated epitaxial regions (64, 66) in the epitaxial layer, a resistor (40) formed in a first one of the isolated epitaxial regions, electrical conductivity means (74, 78) for both connecting one end of the resistor and a second one of the isolated epitaxial regions to first and second terminals respectively, the first and second terminals being adapted to receive respectively an input voltage signal and an operating potential, the improvement comprising a protection circuit including: first Schottky diode means (88) formed in the first isolated epitaxial region; and second Schottky diode means (90) formed in the second isolated epitaxial layer region, said first and second Schottky diode means forming a clamp circuit for inhibiting turn on of a parasitic silicon controlled rectifier that can otherwise be turned on if the substrate of the monolithic integrated circuit is not at ground reference potential when the input voltage signal and the operating potential are applied to the monolithic integrated circuit.
Claim 6
Dependent Claim
215 words
A monolithic integrated circuit including a substrate (50) of a first conductivity semiconductor material, an epitaxial layer (52) of a second conductivity semiconductor material disposed on the substrate, a plurality of isolating regions (60, 62) of said first conductivity semiconductor material formed through the epitaxial layer in contact with the substrate which produce a plurality of separate isolated epitaxial regions (64, 66) in the epitaxial layer, a resistor (40) formed in a first one of the isolated epitaxial regions, electrical conductivity means (74, 78) for both connecting one end of the resistor and a second one of the isolated epitaxial regions to first and second terminals respectively, the first and second terminals being adapted to receive respectively an input voltage signal and an operating potential, the improvement comprising a protection circuit including: first Schottky diode means (88) formed in the first isolated epitaxial region; and second Schottky diode means (90) formed in the second isolated epitaxial layer region, said first and second Schottky diode means forming a clamp circuit for inhibiting turn on of a parasitic silicon controlled rectifier that can otherwise be turned on if the substrate of the monolithic integrated circuit is not at ground reference potential when the input voltage signal and the operating potential are applied to the monolithic integrated circuit.
References Cited (Backward Citations)
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