Sense FET having a selectable sense current ratio and method of manufacturing the same
First Claim
1. A sense FET comprising:
- a main cell array having a plurality of MOSFET cells connected in parallel;
a main pad electrically connected to sources of the MOSFET cells of the main cell array;
a plurality of sense cell arrays composed of a plurality of unit sense cells having drains and gates connected to drains and gates respectively of the MOSFET cells of the main cell array, wherein the sense cell arrays are composed of different numbers of unit sense cells; and
a plurality of sense pads corresponding to each of the plurality of sense cell arrays, each sense pad being electrically connected to sources of the unit sense cells of the corresponding sense cell array.
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Accused Products
Abstract
A sense FET is provided that is capable of achieving one of many available sense current ratios after manufacture, and a method of manufacturing the same. The sense FET includes a main cell array of MOSFET cells connected in parallel, and a main pad connected to the sources of the main cells. A plurality of unit sense cells are arranged in arrays, and also optionally in groups corresponding to portions of the arrays. A plurality of sense pads are electrically insulated from each other. Each sense pad is connected to the sources of the unit sense cells of either a complete sense cell array, or of a group corresponding to a portion of an array. Every sense pad is connected either to the sense resistor or to the main pad. When connected to a sense resistor, the corresponding unit cells are used as sense cells. For every different combination of sense pads that are connected to the sense resistor, a different number of unit cells are used as sense cells, and therefore a different sense current ratio is effectuated for the device. Connection to the sense resistor is by a reconfigurable wire bonding process, or by cutting electrically metal thin film fuses that initially connect the sense pads. The fuses can also initially join the sense pads to the main pad. This way the unit cells of unused sense pads can act instead as main cells.
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Citations
24 Claims
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1. A sense FET comprising:
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a main cell array having a plurality of MOSFET cells connected in parallel;
a main pad electrically connected to sources of the MOSFET cells of the main cell array;
a plurality of sense cell arrays composed of a plurality of unit sense cells having drains and gates connected to drains and gates respectively of the MOSFET cells of the main cell array, wherein the sense cell arrays are composed of different numbers of unit sense cells; and
a plurality of sense pads corresponding to each of the plurality of sense cell arrays, each sense pad being electrically connected to sources of the unit sense cells of the corresponding sense cell array. - View Dependent Claims (2, 3, 4)
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5. A sense FET comprising:
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a main cell array having a plurality of MOSFET cells connected in parallel;
a main pad electrically connected to sources of the MOSFET cells of the main cell array;
a sense cell array composed of a plurality of unit sense cells arranged in groups, each unit sense cell having a gate and drain connected to gates and drains respectively of the MOSFET cells of the main cell array;
a plurality of sense pads each of which has at least one center sense pad to which a wire is to be connected and at least one auxiliary sense pad to which the wire is not connected, corresponding to each of the plurality of the groups, each source pad electrically connected to sources of the unit sense cells of the corresponding group; and
at least one metal thin film fuse capable of being electrically cut for connecting the center sense pad to the auxiliary sense pad, respectively. - View Dependent Claims (6, 7, 8, 9, 10, 11)
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12. A sense FET comprising:
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a main cell array having a plurality of MOSFET cells connected in parallel;
a main pad electrically connected to sources of the MOSFET cells of the main cell array;
a plurality of sense cell arrays composed of a plurality of unit sense cells having gates and drains connected to gates and drains respectively of the MOSFET cells of the main cell array;
a plurality of sense pads corresponding to each of the plurality of sense cell arrays, each sense pad being electrically connected to sources of the unit sense cells of the corresponding sense cell array; and
a plurality of metal thin film fuses capable of being electrically cut for connecting the sense pads to each other and to the main pad. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method of forming a sense FET comprising the steps of:
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forming a main cell array having a plurality of MOSFET cells connected in parallel and a plurality of unit sense cells, the unit sense cells arranged in a plurality of groups and having drains and gates connected to drains and gates respectively of the MOSFET cells of the main cell array;
forming a main pad electrically connected to sources of the MOSFET cells of the main cell array and a plurality of sense pads, each sense pad being electrically connected to sources of the unit sense cells of a single group; and
forming at least one fuse connecting one of the sense pads to one of the main pad and another one of the sense pads. - View Dependent Claims (19, 20, 21, 22)
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23. A method of forming a sense FET comprising:
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forming a main cell array having a plurality of MOSFET cells connected in parallel and a plurality of unit sense cells, the unit sense cells arranged in a plurality of groups and having drains and gates connected to drains and gates respectively of the MOSFET cells of the main cell array;
forming a main pad electrically connected to sources of the MOSFET cells of the main cell array and a plurality of sense pads, each sense pad being electrically connected to sources of the unit sense cells of a single group;
forming at least one fuse connecting one of the sense pads to one of the main pad and another one of the sense pads; and
wire bonding at least one of the sense pads to a terminal of a sense FET package. - View Dependent Claims (24)
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Specification