What is claimed:
1. A programmable delay cell, comprising:
a cell input;
a cell output;
a plurality of delay elements, each having an element input and an element output, at least one element input being coupled to said cell input; and
a connection matrix having a plurality of inputs and an output, said connection matrix output being coupled to said cell output;
said connection matrix inputs being coupled to one or more of said delay element outputs;
wherein said connection matrix inputs are selectively couplable to said connection matrix output to provide a desired delay at said cell output.
2. A programmable delay cell according to claim 1, further comprising:
a plurality of connection matrices;
a first plurality of delay elements coupled between said cell input and a first connection matrix; and
a second plurality of delay elements coupled between an output of said first connection matrix and a second connection matrix.
3. A programmable delay cell according to claim 1, wherein said connection matrix inputs are disposed closely adjacent said connection matrix output on a circuit layout to inhibit the placing of connection leads in the space between said connection matrix inputs and connection matrix output.
4. A method of designing a logic circuit incorporating a programmable delay cell, comprising the steps of:
(a) laying out logic elements of the logic circuit, wherein at least one logic element comprises a clock circuit;
(b) laying out the programmable delay cell, which comprises a cell input, a cell output, a plurality of delay elements, each having an element input and an element output, at least one element input being coupled to said cell input, a connection matrix having a plurality of inputs and an output, the connection matrix output being coupled to the cell output, the connection matrix inputs being coupled to one or more of the delay element outputs;
(c) routing connection leads from the clock circuit to the programmable delay cell input and from the programmable delay cell output to the remaining logic elements of the logic circuit;
(d) performing a clock tree analysis to determine the delays between the clock circuit and the remaining logic elements; and
(e) configuring the programmable delay cell to balance the delays among the logic elements of the logic circuit.
5. The method according to claim 4, comprising the further steps of:
(f) initially configuring the programmable delay cell to have a minimum delay effect;
(g) thereafter performing step (d); and
(h) thereafter reconfiguring the programmable delay cell to balance the delays among the logic elements.
6. The method according to claim 4, comprising the further step of:
(f) locating the connection matrix inputs closely adjacent the connection matrix output to thereby inhibit the placing of connection leads to remaining logic elements of the logic circuit between the connection matrix inputs and connection matrix output.
7. An integrated circuit, comprising:
a plurality of logic elements, wherein at least one logic element comprises a clock circuit;
a programmable delay cell, having
a cell input,
a cell output,
a plurality of delay elements, each having an element input and an element output, at least one element input being coupled to said cell input,
a connection matrix having a plurality of inputs and an output, the connection matrix output being coupled to the cell output,
the connection matrix inputs being coupled to one or more of the delay element outputs;
means for coupling the clock circuit to the programmable delay cell input; and
means for coupling the programmable delay cell output to at least one of the remaining logic elements;
wherein said connection matrix inputs are selectively couplable to said connection matrix output to provide a desired delay at said cell output.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A cooling system for a gas turbine engine, comprising:
at least one first surface defining at least a portion of the cooling system; and
at least one pin fin extending from the at least one first surface;
wherein the at least one pin fin has a noncircular cross-section taken generally parallel to the at least one first surface, wherein at least part of an outer surface of the cross-section forms at least a quartercircle;
wherein the at least one pin fin comprises at least one three quarter circular outer surface positioned on an upstream side of the at least one pin fin;
wherein the at least one pin fin includes a three quarter circular downstream surface forming a three quarter circular cavity within the at least one pin fin, wherein the three quarter downstream surface is coupled to the outer surface with linear surfaces.
2. A cooling system for a gas turbine engine, comprising:
at least one first surface defining at least a portion of the cooling system; and
at least one pin fin extending from the at least one first surface to a second inner surface;
wherein the at least one pin fin has a noncircular cross-section taken generally parallel to the at least one first surface, wherein at least part of an outer surface of the cross-section forms at least a quartercircle;
wherein the at least one pin fin is formed from first and second sections divided by a cavity generally aligned with a longitudinal axis of cooling fluid flow.
3. The cooling system of claim 2, wherein the at least one pin fin comprises at least one semicircular outer surface positioned on the first section and at least one semicircular outer surface positioned on the second section.
4. The cooling system of claim 3, wherein the first section includes a concave inner surface and the second section includes a concave inner surface, wherein the concave inner surfaces are opposed to each other.
5. The cooling system of claim 3, wherein the first section includes a concave, semicircular inner surface and the second section includes a concave, semicircular inner surface, wherein the concave, semicircular inner surfaces are opposed to each other.
6. The cooling system of claim 2, wherein the first section comprises at least one three eights circular outer surface positioned on an upstream side of the first section, and the second section comprises at least one three eights circular outer surface positioned on an upstream side of the second section.
7. The cooling system of claim 6, wherein the first section further comprises a generally linear side surface positioned on a downstream side of the first section, and the second section further comprises a generally linear side surface positioned on a downstream side of the second section, wherein the downstream, generally linear sides of the first and second sections form a one quarter, pie shaped cavity.
8. The cooling system of claim 6, wherein the first section includes a three eights circular downstream surface forming an inner curved surface coupled to the outer surface with a linear surface, and the second section includes a three eights circular downstream surface forming an inner curved surface coupled to the outer surface with a linear surface.
9. An airfoil for a gas turbine engine, comprising:
a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side wall, a suction side wall positioned generally opposite from the pressure side wall;
a cooling system in the generally elongated hollow airfoil, comprising at least one first surface defining at least a portion of the cooling system; and
at least one pin fin extending from the at least one first surface and contacting a second inner surface;
wherein the at least one pin fin has a noncircular cross-section taken generally parallel to the at least one first surface, wherein at least part of an outer surface of the cross-section forms at least a quartercircle;
wherein the at least one pin fin comprises at least one three quarter circular outer surface positioned on an upstream side of the at least one pin fin and includes a three quarter circular downstream surface forming a three quarter circular cavity within the at least one pin fin, wherein the three quarter downstream surface is coupled to the outer surface with linear surfaces.
10. An airfoil for a gas turbine engine, comprising:
a generally elongated hollow airfoil formed from an outer wall, and having a leading edge, a trailing edge, a pressure side wall, a suction side wall positioned generally opposite from the pressure side wall;
a cooling system in the generally elongated hollow airfoil, comprising at least one first surface defining at least a portion of the cooling system; and
at least one pin fin extending from the at least one first surface and contacting a second inner surface;
wherein the at least one pin fin has a noncircular cross-section taken generally parallel to the at least one first surface, wherein at least part of an outer surface of the cross-section forms at least a quartercircle;
wherein the at least one pin fin is formed from first and second sections divided by a cavity generally aligned with a longitudinal axis of cooling fluid flow.
11. The airfoil of claim 10, wherein the at least one pin fin comprises at least one semicircular outer surface positioned on the first section and at least one semicircular outer surface positioned on the second section, wherein the first section includes a concave inner surface and the second section includes a concave inner surface, wherein the concave inner surfaces are opposed to each other.
12. The airfoil of claim 10, wherein the at least one pin fin comprises at least one semicircular outer surface positioned on the first section and at least one semicircular outer surface positioned on the second section, wherein the first section includes a concave, semicircular inner surface and the second section includes a concave, semicircular inner surface, wherein the concave, semicircular inner surfaces are opposed to each other.
13. The airfoil of claim 10, wherein the first section comprises at least one three eights circular outer surface positioned on an upstream side of the first section, and the second section comprises at least one three eights circular outer surface positioned on an upstream side of the second section, wherein the first section further comprises a generally linear side surface positioned on a downstream side of the first section, and the second section further comprises a generally linear side surface positioned on a downstream side of the second section, wherein the downstream, generally linear sides of the first and second sections form a one quarter, pie shaped cavity.
14. The airfoil of claim 10, wherein the first section comprises at least one three eights circular outer surface positioned on an upstream side of the first section, and the second section comprises at least one three eights circular outer surface positioned on an upstream side of the second section, wherein the first section includes a three eights circular downstream surface forming an inner curved surface coupled to the outer surface with a linear surface, and the second section includes a three eights circular downstream surface forming an inner curved surface coupled to the outer surface with a linear surface.