US6405347B1
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Method and apparatus for determining the maximum permitted and minimum required width of a feedback FET on a precharge node
Assignee: Hewlett Packard Development Co LP
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Filing: 1999-06-30
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Granted: 2002-06-11
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Expires: 2019-06-30
Abstract
Abstract In accordance with one aspect of the invention a method is provided for determining a minimum FET width for a feedback FET on a precharge node. In one embodiment, the method identifies the NFET (ignoring evaluation NFETs) of each NFET tree having the largest width value. then sums width the values of these largest NFETs in at least one NFET tree associated with the precharge node, to determine an effective NFET width (N) of NFETs in the at least one NFET tree. Then, the method computes a minimum value of a PFET width (P) for the feedback FET, for a specified N:P ratio (R), in accordance with the equation: P=N/R. In accordance with another aspect of the invention a method is provided for determining a maximum FET width for a feedback FET on a precharge node. In one embodiment, the method evaluates at least one NFET tree, in accordance with a second circuit model, to determine an effective NFET width (N). This evaluation includes computing an effective width value of each NFET tree, and determining which NFET tree has the largest effective width. The method then computes a maximum value of an effective PFET width (P 2 ) for the feedback FET tree, for a specified N 2 :P 2 ratio (R 2 ), in accordance with the equation P 2 =N 2 /R 2.
Inventors
- 👤 John G McBride
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 22:57
CPC Classifications
G; G06; G06F; G06F30/00; G06F30/30; G06F30/32; G06F30/33
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
145 words
A method for determining a maximum FET width and a minimum FET width for a feedback FET on a precharge node, comprising the steps of: identifying a precharge node; detecting a feedback FET tree on the precharge node; evaluating at least one NFET tree, in accordance with a first circuit model, to determine an effective NFET width (N) of FETs in the at least one NFET tree; computing a minimum value of a PFET width (P) for the feedback FET tree, for a specified N:P ratio; evaluating the at least one NFET tree, in accordance with a second circuit model, to determine an effective NFET width (N 2 ) of the FETs in the at least one NFET tree; and computing a maximum value of an effective PFET width (P 2 ) for the feedback FET tree, for a specified N 2 :P 2 ratio.
Claim 2
Independent Claim
145 words
A method for determining a maximum FET width and a minimum FET width for a feedback FET on a precharge node, comprising the steps of: identifying a precharge node; detecting a feedback FET tree on the precharge node; evaluating at least one NFET tree, in accordance with a first circuit model, to determine an effective NFET width (N) of FETs in the at least one NFET tree; computing a minimum value of a PFET width (P) for the feedback FET tree, for a specified N:P ratio; evaluating the at least one NFET tree, in accordance with a second circuit model, to determine an effective NFET width (N 2 ) of the FETs in the at least one NFET tree; and computing a maximum value of an effective PFET width (P 2 ) for the feedback FET tree, for a specified N 2 :P 2 ratio.
Claim 3
Dependent Claim
39 words
The method as defined in claim 1 , wherein the step of detecting a feedback FET tree more specifically includes detecting at least one feedback PFET, the feedback FET tree being an effective FET including at least one PFET.
Claim 4
Dependent Claim
56 words
The method as defined in claim 1 , wherein the step of evaluating at least one NFET tree, in accordance with a first circuit model, to determine an effective NFET width (N), includes approximating an effective FET width to be equal to the FET width of the largest FET in the at least one NFET tree.
Claim 5
Dependent Claim
23 words
The method as defined in claim 3 , further including the step of determining whether a given, individual NFET is an evaluation FET.
Claim 6
Dependent Claim
31 words
The method as defined in claim 4 , wherein the step of approximating an effective FET width more specifically includes ignoring the value of those NFETs determined to be evaluation FETs.
Claim 7
Dependent Claim
47 words
The method as defined in claim 1 , wherein the step of computing a minimum value of a PFET width (P) more particularly includes retrieving the specified (N:P) ratio, wherein the specified N:P ratio is a design ratio that is specified by a user of the method.
Claim 8
Dependent Claim
74 words
The method as defined in claim 1 , wherein the step of evaluating at least one NFET tree, in accordance with a second circuit model, to determine an effective NFET width (N), includes combining series connected FETs by dividing the product of their widths by the sum of their widths, and further includes combining parallel connected FETs by approximating an effective width equal to a larger width value of the channel parallel connected FETs.
Claim 9
Dependent Claim
101 words
The method as defined in claim 7 , wherein the step of evaluating at least one NFET tree, in accordance with a second circuit model, to determine an effective NFET width (N), includes accumulating width values of individual NFETs in accordance with the following equation: N 2 =1/((1 /w 1 )+(1 /w 2 )+ . . . +(1 /wn )). where w 1 , w 2 , . . . , wn are width values for a first NFET, a second NFET, . . . , and an nth NFET in the NFET tree identified as having the maximum width summation.
Claim 10
Dependent Claim
151 words
The method as defined in claim 7 , wherein the step of evaluating at least one NFET tree, in accordance with a second circuit model, to determine an effective NFET width (N), includes accumulating width values of individual NFETs in accordance with the following equation: N 2 = Lp /(( L 1 / w 1 )+( L 2 / w 2 )+ . . . +( Ln/wn )), where w 1 , w 2 , . . . , wn are width values for a first NFET, a second NFET, . . . , and an nth NFET, where Lp is a FET length specified by a fabrication process, and L 1 , L 2 , . . . , Ln are FET length values for the first NFET, the second NFET, . . . , and the nth NFET, in the NFET tree identified as having the maximum width summation.
Claim 11
Dependent Claim
35 words
The method as defined in claim 1 , further including the step of determining whether the FET width of the feedback FET tree exceeds the value P, and generating a warning message if it does.
Claim 12
Dependent Claim
39 words
The method as defined in claim 1 , further including the step of determining whether the FET width of the feedback FET tree is smaller than the value P 2 , and generating a warning message if it does.
Claim 13
Independent Claim
79 words
A method for determining a minimum FET width for a feedback FET on a precharge node, comprising the steps of: summing width values of individual NFETs in at least one NFET tree associated with the precharge node, to determine an effective NFET width (N) of NFETs in the at least one NFET tree; and computing a minimum value of a PFET width (P) for the teedback FET, for a specified N:P ratio (R), in accordance with the equation: P=N/R.
Claim 14
Independent Claim
79 words
A method for determining a minimum FET width for a feedback FET on a precharge node, comprising the steps of: summing width values of individual NFETs in at least one NFET tree associated with the precharge node, to determine an effective NFET width (N) of NFETs in the at least one NFET tree; and computing a minimum value of a PFET width (P) for the teedback FET, for a specified N:P ratio (R), in accordance with the equation: P=N/R.
Claim 15
Dependent Claim
23 words
The method as defined in claim 12 , further including the step of determining whether a given, individual NFET is an evaluation FET.
Claim 16
Dependent Claim
42 words
The method as defined in claim 13 , wherein the step of summing width values more specifically includes summing width values of the largest NFET in each of the at least one NFET tree, except those NFETs determined to be evaluation FETs.
Claim 17
Dependent Claim
36 words
The method as defined in claim 12 , further including the step of determining whether a FET width of the feedback FET exceeds the minimum FET width value, and generating a warning message if it does.
Claim 18
Independent Claim
159 words
A method for determining a maximum FET width for a feedback FET on a precharge node, comprising the steps of: evaluating at least one NFET tree, in accordance with a first circuit model, to determine an effective NFET width (N), including combining series connected FETs by dividing the product of their widths by the sum of their widths, and further includes combining parallel connected FETs by approximating an effective width equal to a larger width value of the channel parallel connected FETs; accumulating width values of individual NFETs in the at least one NFET tree associated with the precharge node to determine an effective NFET width (N 2 ) of NFETs in the at least one NFET tree; and computing a maximum value of an effective PFET width (P 2 ) for the feedback FET tree, for a specified N 2 :P 2 ratio (R 2 ), in accordance with the equation P 2 =N 2 /R 2 .
Claim 19
Independent Claim
159 words
A method for determining a maximum FET width for a feedback FET on a precharge node, comprising the steps of: evaluating at least one NFET tree, in accordance with a first circuit model, to determine an effective NFET width (N), including combining series connected FETs by dividing the product of their widths by the sum of their widths, and further includes combining parallel connected FETs by approximating an effective width equal to a larger width value of the channel parallel connected FETs; accumulating width values of individual NFETs in the at least one NFET tree associated with the precharge node to determine an effective NFET width (N 2 ) of NFETs in the at least one NFET tree; and computing a maximum value of an effective PFET width (P 2 ) for the feedback FET tree, for a specified N 2 :P 2 ratio (R 2 ), in accordance with the equation P 2 =N 2 /R 2 .
Claim 20
Dependent Claim
92 words
The method as defined in claim 16 , wherein the step of accumulating width values of individual NFETs in the at least one NFET tree, accumulates the value N 2 in accordance with the following equation: N 2 =1/((1 /w 1 )+(1 /w 2 )+ . . . +(1 /wn )), where w 1 , w 2 , . . . , wn are width values for a first NFET, a second NFET, . . . , and an nth NFET in the NFET tree identified as having the maximum width summation.
Claim 21
Dependent Claim
142 words
The method as defined in claim 16 , wherein the step of accumulating width values of individual NFETs in the at least one NFET tree, accumulates the value N 2 in accordance with the following equation: N 2 = Lp /(( L 1 / w 1 )+( L 2 / w 2 )+ . . . +( Ln/wn )), where w 1 , w 2 , . . . , wn are width values for a first NFET, a second NFET, . . . , and an nth NFET, where Lp is a FET length specified by a fabrication process, and L 1 , L 2 , . . . , Ln are FET length values for the first NFET, the second NFET, . . . , and the nth NFET, in the NFET tree identified as having the maximum width summation.
Claim 22
Dependent Claim
38 words
The method as defined in claim 16 , further including the step of determining whether a FET width of the feedback FET is smaller than the minimum FET width value, and generating a warning message if it does.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2005-06-10 | 2005-12-10 | 2006-06-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2009-06-10 | 2009-12-10 | 2010-06-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2013-06-10 | 2013-12-10 | 2014-06-11 | $7700.00 | Window Closed / Lapsed |