Field-effect transistor device with partial finger current sensing FETs
First Claim
1. A lateral semiconductor field-effect transistor (FET) device fabricated on a substrate comprising:
- a high-voltage main FET having interdigitated, elongated source and drain electrode fingers each of which is electrically connected to a respective interdigitated, elongated source and drain region disposed in the substrate;
first and second sense FETs each having a drain region in common with the high-voltage main FET, and respective first and second elongated source electrode fingers each of which is electrically connected to respective first and second elongated source regions of the first and second sense FETs, respectively, the first and second elongated source electrode fingers being disposed length-wise adjacent to one of the elongated drain electrode fingers, the first elongated source finger having a first length, and the second elongated source finger having a second length, the second length being less than the first length;
wherein when the high-voltage main FET and the first and second sense FETs are in an on-state, first and second sense currents respectively flow through the first and second sense FETs, the first current being larger than the second current, with the sum of the first and second currents being a relatively small fraction of a drain current flowing through the high-voltage main FET.
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Abstract
A lateral semiconductor field-effect transistor (FET) device fabricated on a substrate includes a high-voltage main FET having interdigitated, elongated source and drain electrode fingers each of which is electrically connected to a respective interdigitated, elongated source and drain region disposed in the substrate. The FET device further includes first and second sense FETs each having a drain region in common with the high-voltage main FET. The sense FETS also include respective first and second elongated source electrode fingers each of which is electrically connected to respective first and second elongated source regions of the first and second sense FETs, respectively. The first and second elongated source electrode fingers are disposed length-wise adjacent to one of the elongated drain electrode fingers. The first elongated source finger has a first length, and the second elongated source finger has a second length, the second length being less than the first length.
38 Citations
19 Claims
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1. A lateral semiconductor field-effect transistor (FET) device fabricated on a substrate comprising:
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a high-voltage main FET having interdigitated, elongated source and drain electrode fingers each of which is electrically connected to a respective interdigitated, elongated source and drain region disposed in the substrate; first and second sense FETs each having a drain region in common with the high-voltage main FET, and respective first and second elongated source electrode fingers each of which is electrically connected to respective first and second elongated source regions of the first and second sense FETs, respectively, the first and second elongated source electrode fingers being disposed length-wise adjacent to one of the elongated drain electrode fingers, the first elongated source finger having a first length, and the second elongated source finger having a second length, the second length being less than the first length; wherein when the high-voltage main FET and the first and second sense FETs are in an on-state, first and second sense currents respectively flow through the first and second sense FETs, the first current being larger than the second current, with the sum of the first and second currents being a relatively small fraction of a drain current flowing through the high-voltage main FET. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 12)
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11. An integrated circuit in a substrate comprising:
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a high-voltage main field-effect transistor (FET) having interdigitated, elongated source and drain electrode fingers each of which is electrically connected to a respective interdigitated, elongated source and drain region disposed in the substrate, and a gate disposed over a region of the substrate that separates the source and drain regions; first and second sense FETs each sharing a drain region of the high-voltage main FET, the first sense FET having a first elongated source electrode finger electrically connected to a first elongated source region of the first sense FET, the second sense FET having a second elongated source electrode finger electrically connected to a second elongated source region of the second sense FET, the first and second elongated source electrode fingers being disposed length-wise adjacent to one of the elongated drain electrode fingers, the first elongated source finger having a first length, and the second elongated source finger having a second length, the second length being less than the first length, wherein when the high-voltage main FET and the first and second sense FETs are in an on-state, first and second sense currents respectively flow through the first and second sense FETs; first and second sense resistors coupled in series with the first and second sense FETs, respectively, a first sense voltage being produced across the first sense resistor, and a second sense voltage being produced across the second sense resistor, responsive to the first and second sense currents, respectively; a multiplexer coupled to receive the first and second sense voltages at first and second inputs, respectively, the multiplexer also having an output and a switching control input; and a first comparator having an output coupled to drive the switching control input of the multiplexer, and a pair of inputs coupled to compare the first sense voltage with a first limit voltage, when the first sense voltage is less than the first limit voltage the first sense voltage is provided at the output of the multiplexer, and when the first sense voltage exceeds the first limit voltage, the second sense voltage is provided at the output of the multiplexer. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification