US4891604A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High speed low input current voltage follower stage
Assignee: Intersil Corp
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Filing: 1988-12-27
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Granted: 1990-01-02
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Expires: 2008-12-27
Abstract
Abstract A voltage follower input stage having a correction or bootstrap circuit to effectively remove the parasitic capacitance by bootstrapping the capacitance so that both sides of the parasitic capacitance follows voltage level changes.
Inventors
- 👤 Gerald M. Cotreau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:57
CPC Classifications
H; H03; H03F; H03F3/00; H03F3/50; H03F3/45; H03F3/45071; H03F3/45076; H03F3/4508; H03F3/45085; H03F3/45089
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
151 words
Low input current voltage follower stage comprising: first transistor having a base connected to an input terminal and having an emitter-collector path connected at a first end to a first reference terminal; a current source means connecting a second end of said first transistor's emitter-collector path to a second reference terminal and including a parasitic capacitance between a first and second terminal; said bootstrap means connected in parallel to said current source means first and second terminal for causing both sides of said parasitic capacitance to follow changes of voltage at said second end of said first transistor's emitter-collector path; and bootstrap means including a second transistor having a base connected to said second end of said first transistor's emitter-collector path and said first terminal of said current source means and having a second end of said second transistor's emitter-collector path connected to said second terminal of said current source means.
Claim 2
Dependent Claim
151 words
Low input current voltage follower stage comprising: first transistor having a base connected to an input terminal and having an emitter-collector path connected at a first end to a first reference terminal; a current source means connecting a second end of said first transistor's emitter-collector path to a second reference terminal and including a parasitic capacitance between a first and second terminal; said bootstrap means connected in parallel to said current source means first and second terminal for causing both sides of said parasitic capacitance to follow changes of voltage at said second end of said first transistor's emitter-collector path; and bootstrap means including a second transistor having a base connected to said second end of said first transistor's emitter-collector path and said first terminal of said current source means and having a second end of said second transistor's emitter-collector path connected to said second terminal of said current source means.
Claim 3
Dependent Claim
43 words
A follower stage according to claim 1, wherein said current source means includes third transistor having a first end of an emitter-collector path connected to said current source means first terminal and having a base connected to said current source means second terminal.
Claim 4
Dependent Claim
32 words
A follower stage according to claim 2, wherein said current source means includes a first current source connecting a second end of said third transistor's emitter-collector path to said second reference terminal.
Claim 5
Dependent Claim
24 words
A follower stage according to claim 3, including a diode connecting said second end of said second transistor's emitter to said first current source.
Claim 6
Dependent Claim
30 words
A follower stage according to claim 4, wherein said third transistor is substantially smaller than said diode so that said second transistor conducts substantially more current than said first transistor.
Claim 7
Dependent Claim
33 words
A follower stage according to claim 5, wherein said third transistor and said diode are sized so that said second transistor conducts at least ten times the current that said first transistor conducts.
Claim 8
Dependent Claim
19 words
A follower stage according to claim 1, including a level shifting means connected to said second transistor's emitter-collector path.
Claim 9
Dependent Claim
70 words
A follower stage according to claim 7, wherein said level shifter means includes: a second current source connecting said first end of said second transistor's emitter-collector path to said first reference terminal; and a fourth transistor having emitter-collector path connected between a first end of said second transistor's emitter-collector path and said second reference terminal and having a base connected to said second end of said second transistor's emitter-collector path.
Claim 10
Dependent Claim
54 words
A follower stage according to claim 1, wherein said bootstrap means includes a second bootstrap means connected in parallel to said emitter-collector path of said second transistor for causing both sides of the base-collector capacitance of said second transistor to follow change of voltage at said second end of said first transistor's emitter-collector path.
Claim 11
Dependent Claim
131 words
Low input current voltage follower stage comprising: first transistor having a base connected to an input terminal and having an emitter-collector path connected at a first end to a first reference terminal; a current source means connecting a second end of said first transistor's emitter-collector path to a second reference terminal, including a parasitic capacitance between a first and second terminal, and including third transistor having a first end of a emitter-collector path connected to said current source means first terminal and having a base connected to said current source means second terminal; and bootstrap means connected in parallel to said current source means first and second terminal for causing both sides of said parasitic capacitance to follow changes of voltage at said second end of said first transistor's emmitter-collector path.
Claim 12
Dependent Claim
131 words
Low input current voltage follower stage comprising: first transistor having a base connected to an input terminal and having an emitter-collector path connected at a first end to a first reference terminal; a current source means connecting a second end of said first transistor's emitter-collector path to a second reference terminal, including a parasitic capacitance between a first and second terminal, and including third transistor having a first end of a emitter-collector path connected to said current source means first terminal and having a base connected to said current source means second terminal; and bootstrap means connected in parallel to said current source means first and second terminal for causing both sides of said parasitic capacitance to follow changes of voltage at said second end of said first transistor's emmitter-collector path.
Claim 13
Dependent Claim
32 words
A follower stage according to claim 10, wherein said current source means includes a first current source connecting a second end of said third transistor's emitter-collector path to said second reference terminal.
Claim 14
Dependent Claim
19 words
A follower stage according to claim 11, including a diode connecting said bootstrap means to said first current source.
Claim 15
Dependent Claim
30 words
A follower stage according to claim 12, wherein said third transistor is substantially smaller than said diode so that said bootstrap means conducts substantially more current than said first transistor.
Claim 16
Dependent Claim
133 words
Low input current voltage follower stage comprising: first transistor having a base connected to an input terminal and having an emitter-collector path connected at a first end to a first reference terminal; a current source means connecting a second end of said first transistor's emitter=collector path to a second reference terminal, including a parasitic capacitance between a first and second terminal, including a first current source connected between said current source means first and second terminals, and including a second current source connected between said current source means second terminal and said second reference terminal; and bootstrap means connected in parallel to said current source means first and second terminal for causing both sides of said parasitic capacitance to follow changes of voltage at said second end of said first transistor's emitter-collector path.
Claim 17
Dependent Claim
133 words
Low input current voltage follower stage comprising: first transistor having a base connected to an input terminal and having an emitter-collector path connected at a first end to a first reference terminal; a current source means connecting a second end of said first transistor's emitter=collector path to a second reference terminal, including a parasitic capacitance between a first and second terminal, including a first current source connected between said current source means first and second terminals, and including a second current source connected between said current source means second terminal and said second reference terminal; and bootstrap means connected in parallel to said current source means first and second terminal for causing both sides of said parasitic capacitance to follow changes of voltage at said second end of said first transistor's emitter-collector path.
Claim 18
Dependent Claim
23 words
A follower stage according to claim 14, wherein said second current source having a substantially larger current capacity than said first current source.
Claim 19
Dependent Claim
32 words
A follower stage according to claim 15, wherein said bootstrap means and said first current source are sized so that said bootstrap means conducts substantially more current than said first current source.
Claim 20
Dependent Claim
129 words
A differential input stage having first and second legs, each connected between a first reference terminal and a first common current source, each leg including: input and output terminals; a first transistor having a base connected to said input terminal and having an emitter-collector path connected at a first end to said first reference terminal; a second transistor having a base connected to a second end of said first transistor's emitter-collector path and having an emitter-collector path connected at a first end to said output terminal; and cancellation means connected between a second end of said second transistor's emitter-collector path, said second end of said first transistor's emitter-collector path and said first common current source for cancelling parasitic capacitance at said second end of said first transistor's emitter-collector path.
Claim 21
Dependent Claim
129 words
A differential input stage having first and second legs, each connected between a first reference terminal and a first common current source, each leg including: input and output terminals; a first transistor having a base connected to said input terminal and having an emitter-collector path connected at a first end to said first reference terminal; a second transistor having a base connected to a second end of said first transistor's emitter-collector path and having an emitter-collector path connected at a first end to said output terminal; and cancellation means connected between a second end of said second transistor's emitter-collector path, said second end of said first transistor's emitter-collector path and said first common current source for cancelling parasitic capacitance at said second end of said first transistor's emitter-collector path.
Claim 22
Dependent Claim
51 words
A differential input stage according to claim 17, wherein said cancellation means includes a third transistor, having a base connected to said second end of said second transistor's emitter-collector path, and having an emitter-collector path connecting said second end of said first transistor's emitter-collector path to said first common current source.
Claim 23
Dependent Claim
35 words
A differential input stage according to claim 18, wherein said second ends of said second transistor's emitter-collector paths of both legs are connected together and to said first common current source by a common diode.
Claim 24
Dependent Claim
33 words
A differential input stage according to claim 19, wherein said third transistors each are substantially smaller than said common diode so that said second transistors conduct substantially more current than said first transistors.
Claim 25
Dependent Claim
54 words
A differential input state according to claim 17, including a second common current source; and wherein each of said legs includes a fourth transistor having a base connected to said second common current source and having an emitter-collector path connected between said output terminal and said first end of said second transistor's emitter-collector path.
Claim 26
Dependent Claim
60 words
A differential input stage according to claim 21, including bootstrap means connected to said fourth transistor's bases and said second ends of said second transistor's emitter-collector path for causing both sides of a parasitic capacitor at said first end of said second transistor's emitter-collector path to follow changes of voltage at said first end of said second transistor's emitter-collector path.
Claim 27
Dependent Claim
46 words
A differential input stage according to claim 22, wherein said bootstrap means includes a fifth transistor having a base connected to said second ends of said second transistor's emitter-collector path and includes an emitter-collector path connected at one end to said bases of said fourth transistors.
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) | 1993-01-01 | 1993-07-03 | 1994-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-01 | 1997-07-03 | 1998-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-01 | 2001-07-03 | 2002-01-02 | $7700.00 | Window Closed / Lapsed |