Solid-state high power device and method
A high-power solid-state transistor structure comprised of a plurality of emitter or gate fingers arranged in a uniform or non-uniform manner to provide improved high power performance is disclosed. Each of the fingers is associated with a corresponding one of a plurality of sub-cells. In an exemplary embodiment, the fingers may be arranged in a 1-D or 2-D form having a “hollow-center” layout where one or more elongated emitter fingers or subcells are left out during design or disconnected during manufacture. In another exemplary embodiment, the fingers may be arranged in a 1-D or 2-D form having one or more “arc-shaped” rows that includes one or more elongated emitter fingers or subcells. The structure can be practically implemented and the absolute thermal stability can be maintained for very high power transistors with reduced adverse effects due to random variation in the manufacturing and design process.
1. A transistor comprising:
a collector;
a base, at least a portion of the base disposed on a portion of the collector;
an emitter; and
a first plurality of emitter subcells extending from the emitter, the first plurality of emitter subcells formed on a first portion of the base, an emitter subcell including an emitter finger;
wherein the first plurality of emitter subcells are arranged to extend generally parallel to each other and to form a first arc-shaped row;
wherein the first plurality of emitter subcells includes a first emitter subcell, a second emitter subcell, and a third emitter subcell, wherein the first emitter subcell is closer to a center of the first arc-shaped row than either of the second emitter subcell and the third emitter subcell, and further wherein the third emitter subcell is farther from the center of the first arc-shaped row than either of the first emitter subcell and the second emitter subcell, wherein a first distance between the first emitter subcell and the second emitter subcell is greater than a second distance between the second emitter subcell and the third emitter subcell.
2. The transistor of claim 1 , wherein the first plurality of emitter subcells are symmetrically arranged with respect to each other about a first axis.
3. The transistor of claim 1 , further comprising a ballast resistor electrically connected in series with at least one of the emitter fingers.
4. The transistor of claim 1 , wherein the second emitter subcell includes a greater number of emitter fingers than the first emitter subcell.
5. The transistor of claim 1 , further comprising:
a second plurality of emitter subcells extending from the emitter, the second plurality of emitter subcells formed on the first portion of the base;
wherein the second plurality of emitter subcells are arranged in a second arc-shaped row.
6. The transistor of claim 5 , wherein the second arc-shaped row is a mirror image of the first arc-shaped row relative to a plane extending between the first arc-shaped row and the second arc-shaped row.
7. The transistor of claim 5 , further comprising:
a third plurality of emitter subcells extending from the emitter, the third plurality of emitter subcells formed on the first portion of the base;
wherein the third plurality of emitter subcells are arranged in a third row, the third row arranged between the first arc-shaped row and the second arc-shaped row.
8. The transistor of claim 7 , wherein the third plurality of emitter subcells are arranged in the third row on either side of a central gap.
9. A transistor comprising:
a collector;
a base, at least a portion of the base disposed on a portion of the collector;
an emitter; and
a first plurality of emitter sub cells extending from the emitter, the first plurality of emitter subcells formed on a first portion of the base, an emitter subcell including an emitter finger;
wherein the first plurality of emitter sub cells are arranged to extend generally parallel to each other on either side of a central gap and in a first arc-shaped row; and
further wherein the first plurality of emitter subcells includes a first emitter subcell, a second emitter subcell, and a third emitter subcell, wherein the second emitter subcell includes a greater number of emitter fingers than the first emitter subcell; and further wherein the first emitter subcell is closer to a center of the first row than either of the second emitter subcell and the third emitter subcell, and further wherein the third emitter subcell is farther from the center of the first row than either of the first emitter subcell and the second emitter subcell, wherein a first distance between the first emitter subcell and the second emitter subcell is greater than a second distance between the second emitter subcell and the third emitter subcell.
10. The transistor of claim 9 , further comprising a ballast resistor electrically connected in series with at least one of the emitter fingers.
11. The transistor of claim 9 , further comprising a ballast resistor electrically connected in series with at least one of the emitter fingers wherein a resistance of the ballast resistor is selected based on at least one of the first distance and the second distance.
12. The transistor of claim 9 , wherein the first plurality of emitter subcells are symmetrically arranged with respect to each other about a first axis.
13. The transistor of claim 9 , further comprising:
a second plurality of emitter sub cells extending from the emitter, the second plurality of emitter subcells formed on the first portion of the base;
wherein the second plurality of emitter subcells are arranged in a second row.
14. The transistor of claim 13 , further comprising:
a third plurality of emitter subcells extending from the emitter, the third plurality of emitter subcells formed on the first portion of the base;
wherein the third plurality of emitter subcells are arranged in a third row, the third row arranged between the first arc-shaped row and the second row.
15. The transistor of claim 13 , wherein the second plurality of emitter subcells are arranged in the second row on either side of a second central gap.
16. The transistor of claim 13 , wherein the second row is arc-shaped.
17. The transistor of claim 16 , wherein the first plurality of emitter subcells and the second plurality of emitter subcells are symmetrically arranged with respect to each other about a first axis.
18. A transistor comprising:
a collector;
a base, at least a portion of the base disposed on a portion of the collector;
an emitter;
a first emitter subcell including an emitter finger extending from a first portion of the emitter, the first emitter sub cell formed on a first portion of the base and further including a first lateral side and a second lateral side opposite the first lateral side; and
a second emitter subcell including an emitter finger extending from a second portion of the emitter, the second emitter subcell formed on a second portion of the base and further including a first lateral side and a second lateral side opposite the first lateral side, wherein the first lateral side of the second emitter subcell is proximate the second lateral side of the first emitter subcell;
a third emitter subcell including an emitter finger extending from a third portion of the emitter, the third emitter subcell formed on a third portion of the base and further including a first lateral side and a second lateral side opposite the first lateral side, wherein the first lateral side of the third emitter subcell is proximate the second lateral side of the second emitter subcell;
wherein the first emitter subcell, the second emitter subcell, and the third emitter subcell are arranged in a row;
wherein the first lateral side of the first emitter subcell and the first lateral side of the second emitter subcell are separated by a first distance;
wherein the first lateral side of the second emitter subcell and the first lateral side of the third emitter sub cell are separated by a second distance, and
further wherein the first distance is greater than twice the second distance.
19. A transistor comprising:
a collector;
a base, at least a portion of the base disposed on a portion of the collector;
an emitter; and
a first plurality of emitter subcells extending from the emitter, the first plurality of emitter subcells formed on a first portion of the base, an emitter subcell including an emitter finger;
wherein the first plurality of emitter subcells are arranged to extend generally parallel to each other on either side of a central gap and in a first row; and
further wherein the first plurality of emitter subcells includes a first emitter subcell, a second emitter subcell, and a third emitter subcell, wherein the first emitter subcell is closer to a center of the first row than either of the second emitter subcell and the third emitter subcell, and further wherein the third emitter subcell is farther from the center of the first row than either of the first emitter subcell and the second emitter subcell, wherein a first distance between the first emitter subcell and the second emitter subcell is greater than a second distance between the second emitter subcell and the third emitter subcell.
20. The transistor of claim 19 , wherein the second emitter subcell includes a greater number of emitter fingers than the first emitter subcell.
21. The transistor of claim 20 , further comprising a ballast resistor electrically connected in series with at least one of the emitter fingers wherein a resistance of the ballast resistor is selected based on at least one of the first distance and the second distance.