Low forward voltage rectifier
First Claim
1. An electronic device comprising:
- a current transformer having a first winding and a second winding, the first winding having a first end and a second end, the second winding having a first end and a second end;
a bipolar transistor having a first terminal, a second terminal, and a third terminal, wherein the second terminal is a base terminal, wherein the second end of the first winding of the current transformer is coupled to the second terminal of the bipolar transistor, and wherein the second end of the second winding of the current transformer is coupled to the first terminal of the bipolar transistor;
a diode having an anode and a cathode, wherein the anode is coupled to the first terminal of the bipolar transistor, and wherein the cathode is coupled to the third terminal of the bipolar transistor; and
a package having a first package terminal and a second package terminal, wherein the first package terminal is coupled to the first end of the first winding of the current transformer, wherein the first package terminal is coupled to the first end of the second winding of the current transformer, wherein the second package terminal is coupled to the third terminal of the bipolar transistor, wherein the package encapsulates the current transformer, the bipolar transistor, and the diode, wherein the first winding has a first number of turns, wherein the second winding has a second number of turns, wherein the first number is at least twice as large as the second number, and wherein an increase in a first current flow from the first package terminal through the second winding to the first terminal of the bipolar transistor results in an increase in a second current flow from the first package terminal through the first winding to the second terminal of the bipolar transistor.
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Accused Products
Abstract
A Low Forward Voltage Rectifier (LFVR) includes a bipolar transistor, a parallel diode, and a base current injection circuit disposed in an easy-to-employ two-terminal package. In one example, the transistor is a Reverse Bipolar Junction Transistor (RBJT), the diode is a distributed diode, and the base current injection circuit is a current transformer. Under forward bias conditions (when the voltage from the first package terminal to the second package terminal is positive), the LFVR conducts current at a rated current level with a low forward voltage drop (for example, approximately 0.1 volts). In reverse bias conditions, the LFVR blocks current flow. Using the LFVR in place of a conventional silicon diode rectifier in the secondary of a flyback converter reduces average power dissipation and increases power supply efficiency.
19 Citations
17 Claims
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1. An electronic device comprising:
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a current transformer having a first winding and a second winding, the first winding having a first end and a second end, the second winding having a first end and a second end; a bipolar transistor having a first terminal, a second terminal, and a third terminal, wherein the second terminal is a base terminal, wherein the second end of the first winding of the current transformer is coupled to the second terminal of the bipolar transistor, and wherein the second end of the second winding of the current transformer is coupled to the first terminal of the bipolar transistor; a diode having an anode and a cathode, wherein the anode is coupled to the first terminal of the bipolar transistor, and wherein the cathode is coupled to the third terminal of the bipolar transistor; and a package having a first package terminal and a second package terminal, wherein the first package terminal is coupled to the first end of the first winding of the current transformer, wherein the first package terminal is coupled to the first end of the second winding of the current transformer, wherein the second package terminal is coupled to the third terminal of the bipolar transistor, wherein the package encapsulates the current transformer, the bipolar transistor, and the diode, wherein the first winding has a first number of turns, wherein the second winding has a second number of turns, wherein the first number is at least twice as large as the second number, and wherein an increase in a first current flow from the first package terminal through the second winding to the first terminal of the bipolar transistor results in an increase in a second current flow from the first package terminal through the first winding to the second terminal of the bipolar transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An electronic device comprising:
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a bipolar transistor having an emitter, a base, and a collector; a diode having an anode and a cathode, wherein the anode is coupled to the collector of the bipolar transistor, and wherein the cathode is coupled to the emitter of the bipolar transistor; a package having a first package terminal and a second package terminal, wherein the second package terminal is coupled to the emitter of the bipolar transistor; and means for injecting a base current IB from the first package terminal into the base of the bipolar transistor when a collector current IC is flowing from the first package terminal and through the bipolar transistor from the collector to the emitter, wherein the package encapsulates the bipolar transistor, the diode and the means for injecting, and wherein the means injects the base current such that a voltage drop from the first package terminal, through the bipolar transistor, and to the second package terminal is less than 0.7 volts at a time when the collector current IC is flowing. - View Dependent Claims (12, 13, 14, 15, 16)
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17. An electronic device comprising:
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a bipolar transistor having an emitter, a base, and a collector; a diode having an anode and a cathode, wherein the anode is coupled to the collector of the bipolar transistor, and wherein the cathode is coupled to the emitter of the bipolar transistor; a package having a first package terminal and a second package terminal, wherein the second package terminal is coupled to the emitter of the bipolar transistor; and means for injecting a base current IB from the first package terminal into the base of the bipolar transistor when a collector current Ic is flowing from the first package terminal and through the bipolar transistor from the collector to the emitter, wherein the package encapsulates the bipolar transistor, the diode and the means for injecting, wherein a voltage drop from the first package terminal to the second package terminal is substantially less than 0.7 volts when a current greater than a predetermined critical current is flowing from the first package terminal to the second package terminal, and wherein a voltage drop from the first package terminal to the second package terminal is limited by the diode to approximately 0.8 volts when a current less than the predetermined critical current is flowing from the first package terminal to the second package terminal.
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Specification