EP0382124A2
Expired / Lapsed
EP
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Output buffer with ground bounce control
Assignee: National Semiconductor Corp
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Filing: 1990-02-03
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Granted: —
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Expires: 2010-02-03
Abstract
Abstract An output buffer is described which includes a plurality of pull up transistors (54) connected in parallel and/or a plurality of pull down (64) transistors connected in parallel. A desired amount of resistance (53, 63) is included in the path connecting the gates of the pull up transistors, and in the path connecting the gates of the pull down transistors, thereby providing a distributed RC network causing pull up and pull down transistors to turn on in sequence. This the rate of change of the pull up and pull down current constant, thus reducing ground and Vcc bounce. In another embodiment, a single pull up transistor and/or a single pull down transistor is used. The single transistors have a relatively high gate resistance such that along the channel width of the transistor, the gate capacitance and the gate resistance operates as a distributed RC network. In this manner, portions of the channel begin conducting sequentially, as is the case where a plurality of pull up and pull down transistors are used.
Inventors
- 👤 Mark William Knecht
- 👤 Scott Oliver Frake
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 02:34
CPC Classifications
H; H03; H03K; H03K19/00; H03K19/003; H03K19/00346; H03K19/00361; G; G11; G11C; G11C7/00; G11C7/10; G11C7/1051; H10; H10D; H10D84/00; H10D84/90; H10D84/998
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
138 words
An output circuit comprising: a first supply terminal for receiving a first supply voltage; an input terminal for receiving an input signal; an output terminal for providing an output signal as a result of said input signal; a first plurality of transistors, each having a first current carrying lead coupled to said first supply terminal, a second current carrying lead coupled to said output terminal, and a control lead having a capacitance associated therewith; and a plurality of resistors coupled in series between said control leads of adjacent ones of said plurality of transistors, one of said plurality of resistors also being coupled to said input terminal, wherein said plurality of resistors and said capacitances form a distributed RC network which causes said first plurality of transistors to turn on in sequence in response to said control signal.
Claim 2
Dependent Claim
138 words
An output circuit comprising: a first supply terminal for receiving a first supply voltage; an input terminal for receiving an input signal; an output terminal for providing an output signal as a result of said input signal; a first plurality of transistors, each having a first current carrying lead coupled to said first supply terminal, a second current carrying lead coupled to said output terminal, and a control lead having a capacitance associated therewith; and a plurality of resistors coupled in series between said control leads of adjacent ones of said plurality of transistors, one of said plurality of resistors also being coupled to said input terminal, wherein said plurality of resistors and said capacitances form a distributed RC network which causes said first plurality of transistors to turn on in sequence in response to said control signal.
Claim 3
Dependent Claim
22 words
An output circuit as in claim 1 wherein said resistors comprise resistances associated with said control leads of said plurality of transistors.
Claim 4
Dependent Claim
24 words
An output circuit as in claim 1 wherein said resistors comprise resistances coupled between control leads of adjacent ones of said plurality of transistors.
Claim 5
Dependent Claim
22 words
An output circuit as in claim 3 wherein said resistances comprise polycrystalline silicon interconnects, polycrystalline silicon resistors, diffused resistors, or load devices.
Claim 6
Dependent Claim
26 words
An output circuit as in claim 2 wherein said resistors further comprise additional resistances coupled between control leads of adjacent ones of said plurality of transistors.
Claim 7
Dependent Claim
70 words
An output circuit as in claim 2 wherein each of said transistors comprise MOS transistors having a first source/drain lead serving as said first lead of said transistor, a second source/drain lead serving as said second lead of said transistor, and a gate serving as said control lead of said transistor, wherein said capacitance comprises the gate capacitance of said transistor and said resistance comprises the resistance of said gate.
Claim 8
Dependent Claim
18 words
An output circuit as in claim 1 wherein the resistances of said resistors are of approximately equal values.
Claim 9
Dependent Claim
25 words
An output circuit as in claim 1 wherein the resistance of each of said resistors is greater as its distance from said input terminal increases.
Claim 10
Dependent Claim
25 words
An output circuit as in claim 1 wherein the resistance of each of said resistors is less as its distance from said input terminal increases.
Claim 11
Dependent Claim
22 words
10 . An output circuit as in claim 1 wherein the current carrying capabilitity of each of said transistors is approximately equal.
Claim 12
Dependent Claim
27 words
An output circuit as in claim 1 wherein the current carrying capablitity of each of said transistors is greater as its distance from said input terminal increases.
Claim 13
Dependent Claim
27 words
An output circuit as in claim 1 wherein the current carrying capablitity of each of said transistors is less as its distance from said input terminal increases.
Claim 14
Dependent Claim
57 words
An output circuit as in claim 1 which further comprises one or more turn off switch means, each comprising: a first current carrying terminal coupled to said first supply voltage; a second current carrying terminal coupled to the control lead of a selected one of said switch means; and a control terminal coupled to said input terminal.
Claim 15
Dependent Claim
124 words
An output circuit as in claim 1 which further comprises: a second supply terminal for receiving a second supply voltage; a second plurality of transistors, each having a first current carrying lead coupled to said second supply terminal, a second current carrying lead coupled to said output terminal, and a control lead having a capacitance associated therewith; and a plurality of resistors coupled in series between said control leads of adjacent ones of said second plurality of transistors, one of said second plurality of resistors also being coupled to said input terminal, wherein said second plurality of resistors and said capacitances form a distributed RC network which causes said second plurality of transistors to turn on in sequence in response to said control signal.
Claim 16
Dependent Claim
123 words
An output circuit comprising: a first supply terminal for receiving a first supply voltage; an input terminal for receiving an input signal; an output terminal for providing an output signal as a result of said input signal; and a first MOS transistor having a first source/drain lead coupled to said first supply terminal, a second source/drain lead coupled to said output terminal, a channel located between said first and second source/drain regions, and a control gate coupled to said input terminal and having a capacitance and a resistance associated therewith; wherein said resistance and said capacitance forms a distributed RC network which causes portions of said channel of said first MOS transistor to turn on in sequence in response to said control signal.
Claim 17
Dependent Claim
123 words
An output circuit comprising: a first supply terminal for receiving a first supply voltage; an input terminal for receiving an input signal; an output terminal for providing an output signal as a result of said input signal; and a first MOS transistor having a first source/drain lead coupled to said first supply terminal, a second source/drain lead coupled to said output terminal, a channel located between said first and second source/drain regions, and a control gate coupled to said input terminal and having a capacitance and a resistance associated therewith; wherein said resistance and said capacitance forms a distributed RC network which causes portions of said channel of said first MOS transistor to turn on in sequence in response to said control signal.
Claim 18
Dependent Claim
15 words
An output circuit as in claim 6 or claim 15 said gate comprises polycrystalline silicon.
Claim 19
Dependent Claim
20 words
An output circuit as in claim 16 wherein said polycrystalline silicon is not strapped with metal to reduce its resistance.
Claim 20
Dependent Claim
23 words
An output circuit as in claim 17 wherein said polycrystalline silicon has sheet resistance within the range of approximately 10 to 40 ohms/square.
Claim 21
Dependent Claim
49 words
19 . An output circuit as in claim 17 in combination with other circuitry, said combination further comprising additional portions of polycrystalline silicon not serving as said gate of said first MOS transistor, said additional portions having a sheet resistance with the range of approximately 2 to 10 ohms/square.
Claim 22
Dependent Claim
24 words
An output circuit as in claim 19 wherein said additional portions of polycrystalline silicon are strapped with metal to provide a low resistivity interconnect.
Claim 23
Dependent Claim
29 words
An output circuit as in claim 19 wherein said additional portions of polycrystalline silicon further comprise a refractory metal in order to reduce the resistivity of said additional portions.
Claim 24
Dependent Claim
28 words
An output circuit as in claim 15 wherein the resistance of said gate per unit width of said channel is approximately equal over the length of said gate.
Claim 25
Dependent Claim
29 words
An output circuit as in claim 15 wherein the resistance of said gate per unit width of said channel is greater as its distance from said input terminal increases.
Claim 26
Dependent Claim
29 words
An output circuit as in claim 15 wherein the resistance of said gate per unit width of said channel is less as its distance from said input terminal increases.
Claim 27
Dependent Claim
52 words
An output circuit as in claim 15 which further comprises one or more turn off switch means, each comprising: a first current carrying terminal coupled to said first supply voltage; a second current carrying terminal coupled to a selected location of said gate; and a control terminal coupled to said input terminal.
Claim 28
Dependent Claim
105 words
An output circuit as in claim 15 which further comprises: a second supply terminal for receiving a second supply voltage; and a second MOS transistor having a first source/drain lead coupled to said second supply terminal, a second source/drain lead coupled to said output terminal, a channel located between said first and second source/drain regions, and a control gate coupled to said input terminal and having a capacitance and resistance associated therewith; wherein said resistance and said capacitance forms a distributed RC network which causes portions of said channel of said second MOS transistor to turn on in sequence in response to said control signal.
References Cited (Backward Citations)
No citation records indexed.
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