Patent US5955894A successfully refreshed from Google Patents.
US5955894A
Expired / Lapsed
US
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Method for controlling the impedance of a driver circuit
Assignee: Oracle America Inc
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Filing: 1997-06-25
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Granted: 1999-09-21
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Expires: 2017-06-25
Abstract
Abstract A method for controlling the impedance of drivers controls the output impedance of drivers by coupling the drivers to a impedance control circuit. Accordingly, a desired driver output impedance can advantageously be established and maintained over a wide range of variations in operating conditions and manufacturing processes. Thereby shortening the signal settling time and increasing the attainable signaling frequency.
Inventors
- 👤 Sai V. Vishwanthaiah
- 👤 Jonathan E. Starr
- 👤 Alexander D. Taylor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:21
CPC Classifications
H; H03; H03K; H03K19/00; H03K19/0005
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
126 words
A method for controlling a driver circuit having a base bit element and a controllable bit element to have an output impedance having a known resistance, the method comprising selectively enabling an impedance control bit element using a bit element control signal, the selectively enabled impedance control bit element providing an impedance control bit element resistance; comparing the impedance control bit element resistance to a known resistance to determine when the resistance of the impedance control bit element substantially equals the known resistance; determining whether the controllable bit element is enabled when the resistance of the impedance control bit elements substantially equals the known resistance; and controlling the controllable bit element of the driver circuit based upon whether of the impedance control bit element is enabled.
Claim 2
Independent Claim
126 words
A method for controlling a driver circuit having a base bit element and a controllable bit element to have an output impedance having a known resistance, the method comprising selectively enabling an impedance control bit element using a bit element control signal, the selectively enabled impedance control bit element providing an impedance control bit element resistance; comparing the impedance control bit element resistance to a known resistance to determine when the resistance of the impedance control bit element substantially equals the known resistance; determining whether the controllable bit element is enabled when the resistance of the impedance control bit elements substantially equals the known resistance; and controlling the controllable bit element of the driver circuit based upon whether of the impedance control bit element is enabled.
Claim 3
Dependent Claim
35 words
The method of claim 1 further comprising holding the bit element control signal; and providing a bit control signal to the controllable bit element of the driver circuit based upon the bit element control signal.
Claim 4
Dependent Claim
47 words
The method of claim 2 further comprising determining when the bit element control signal is toggling between two states; and wherein the bit control signal is provided to the controllable bit element of the driver circuit when the bit element control signal is toggling between two states.
Claim 5
Dependent Claim
36 words
The method of claim 1 wherein the driver circuit includes a plurality of controllable bit elements; and further comprising providing a plurality of controllable impedance control bit elements corresponding to the plurality of controllable bit elements.
Claim 6
Dependent Claim
28 words
The method of claim 4 wherein the plurality of controllable bit elements and the plurality of controllable impedance control bit elements are controlled using a thermometer coding scheme.
Claim 7
Dependent Claim
60 words
The method of claim 1 wherein the driver circuit includes a pull up driver circuit, the base bit element and the controllable bit element being within the pull up driver circuit; and the base bit element and the controllable impedance control bit element correspond to the base bit element and the controllable bit element of the pull up driver circuit.
Claim 8
Dependent Claim
33 words
The method of claim 6 further comprising controlling the controllable bit element of the driver circuit such that the output impedance of the pull up driver circuit is slightly above the known resistance.
Claim 9
Dependent Claim
60 words
The method of claim 1 wherein the driver circuit includes a pull down driver circuit, the base bit element and the controllable bit element being within the pull down driver circuit; and the base bit element and the controllable impedance control bit element correspond to the base bit element and the controllable bit element of the pull down driver circuit.
Claim 10
Dependent Claim
33 words
The method of claim 8 further comprising controlling the controllable bit element of the driver circuit such that the output impedance of the pull down driver circuit is slightly below the known resistance.
Claim 11
Independent Claim
177 words
A method for controlling a driver circuit having a base bit element and a plurality of controllable bit element to have an output impedance having a known resistance, the method comprising providing an impedance control base bit element and a plurality of impedance control controllable bit elements; selectively enabling one of the plurality of impedance control controllable bit elements using a bit element control signal, the selectively enabled impedance control controllable bit element providing an impedance control bit element resistance; comparing the impedance control bit element resistance to a known resistance to determine whether the resistance of the impedance control bit element substantially equals the known resistance; repeating the selectively enabling and comparing steps until the resistance of the impedance control bit element resistance substantially equals the known resistance determining which of the plurality of controllable bit elements are enabled when the resistance of the impedance control bit elements substantially equals the known resistance; and controlling the controllable bit elements of the driver circuit based upon which of the plurality of impedance control bit elements are enabled.
Claim 12
Independent Claim
177 words
A method for controlling a driver circuit having a base bit element and a plurality of controllable bit element to have an output impedance having a known resistance, the method comprising providing an impedance control base bit element and a plurality of impedance control controllable bit elements; selectively enabling one of the plurality of impedance control controllable bit elements using a bit element control signal, the selectively enabled impedance control controllable bit element providing an impedance control bit element resistance; comparing the impedance control bit element resistance to a known resistance to determine whether the resistance of the impedance control bit element substantially equals the known resistance; repeating the selectively enabling and comparing steps until the resistance of the impedance control bit element resistance substantially equals the known resistance determining which of the plurality of controllable bit elements are enabled when the resistance of the impedance control bit elements substantially equals the known resistance; and controlling the controllable bit elements of the driver circuit based upon which of the plurality of impedance control bit elements are enabled.
Claim 13
Dependent Claim
28 words
The method of claim 10 wherein the plurality of controllable bit elements and the plurality of controllable impedance control bit elements are controlled using a thermometer coding scheme.
Claim 14
Dependent Claim
60 words
The method of claim 10 wherein the driver circuit includes a pull up driver circuit, the base bit element and the controllable bit element being within the pull up driver circuit; and the base bit element and the controllable impedance control bit element correspond to the base bit element and the controllable bit element of the pull up driver circuit.
Claim 15
Dependent Claim
33 words
The method of claim 12 further comprising controlling the controllable bit element of the driver circuit such that the output impedance of the pull up driver circuit is slightly above the known resistance.
Claim 16
Dependent Claim
60 words
The method of claim 10 wherein the driver circuit includes a pull down driver circuit, the base bit element and the controllable bit element being within the pull down driver circuit; and the base bit element and the controllable impedance control bit element correspond to the base bit element and the controllable bit element of the pull down driver circuit.
Claim 17
Dependent Claim
33 words
The method of claim 14 further comprising controlling the controllable bit element of the driver circuit such that the output impedance of the pull down driver circuit is slightly below the known resistance.
Claim 18
Independent Claim
387 words
A method for controlling a driver circuit having a pull up driver circuit having a pull up base bit element and a plurality of controllable pull up bit elements and a pull down driver circuit having a pull down base bit element and a plurality of controllable pull down bit elements to have an output impedance having a known resistance, the method comprising providing an impedance control pull up base bit element and a plurality of impedance control controllable pull up bit elements, an impedance control pull down base bit element and a plurality of impedance control controllable pull down bit elements; selectively enabling one of the plurality of impedance control controllable pull up bit elements using a pull up bit element control signal, the selectively enabled impedance control controllable pull up bit element providing an impedance control pull up bit element resistance; comparing the impedance control pull up bit element resistance to a known resistance to determine whether the impedance control pull up bit element resistance substantially equals the known resistance; repeating the selectively enabling and comparing steps until the impedance control pull up bit element resistance substantially equals the known resistance; determining which of the plurality of impedance control controllable pull up bit elements are enabled when the impedance control pull up bit element resistance substantially equals the known resistance; and selectively enabling one of the plurality of impedance control controllable pull down bit elements using a pull down bit element control signal, the selectively enabled impedance control controllable pull down bit element providing an impedance control pull down bit element resistance; comparing the impedance control pull down bit element resistance to a known resistance to determine whether the impedance control pull down bit element resistance substantially equals the known resistance; repeating the selectively enabling and comparing steps until the impedance control pull down bit element resistance substantially equals the known resistance; determining which of the plurality of controllable pull down bit elements are enabled when the impedance control pull down bit element resistance substantially equals the known resistance; and controlling the controllable pull up bit elements and the controllable pull down bit elements of the driver circuit based upon which of the plurality of impedance control pull up bit elements and which of the plurality of impedance control pull down bit elements are enabled.
Claim 19
Independent Claim
387 words
A method for controlling a driver circuit having a pull up driver circuit having a pull up base bit element and a plurality of controllable pull up bit elements and a pull down driver circuit having a pull down base bit element and a plurality of controllable pull down bit elements to have an output impedance having a known resistance, the method comprising providing an impedance control pull up base bit element and a plurality of impedance control controllable pull up bit elements, an impedance control pull down base bit element and a plurality of impedance control controllable pull down bit elements; selectively enabling one of the plurality of impedance control controllable pull up bit elements using a pull up bit element control signal, the selectively enabled impedance control controllable pull up bit element providing an impedance control pull up bit element resistance; comparing the impedance control pull up bit element resistance to a known resistance to determine whether the impedance control pull up bit element resistance substantially equals the known resistance; repeating the selectively enabling and comparing steps until the impedance control pull up bit element resistance substantially equals the known resistance; determining which of the plurality of impedance control controllable pull up bit elements are enabled when the impedance control pull up bit element resistance substantially equals the known resistance; and selectively enabling one of the plurality of impedance control controllable pull down bit elements using a pull down bit element control signal, the selectively enabled impedance control controllable pull down bit element providing an impedance control pull down bit element resistance; comparing the impedance control pull down bit element resistance to a known resistance to determine whether the impedance control pull down bit element resistance substantially equals the known resistance; repeating the selectively enabling and comparing steps until the impedance control pull down bit element resistance substantially equals the known resistance; determining which of the plurality of controllable pull down bit elements are enabled when the impedance control pull down bit element resistance substantially equals the known resistance; and controlling the controllable pull up bit elements and the controllable pull down bit elements of the driver circuit based upon which of the plurality of impedance control pull up bit elements and which of the plurality of impedance control pull down bit elements are enabled.
Claim 20
Dependent Claim
35 words
The method of claim 16 further comprising controlling the controllable pull up bit elements of the driver circuit such that the output impedance of the pull up driver circuit is slightly above the known resistance.
Claim 21
Dependent Claim
35 words
The method of claim 16 further comprising controlling the controllable pull down bit element of the driver circuit such that the output impedance of the pull down driver circuit is slightly below the known resistance.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-09-20 | 2003-03-22 | 2003-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-09-20 | 2007-03-22 | 2007-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-09-20 | 2011-03-22 | 2011-09-21 | $7700.00 | Window Closed / Lapsed |