Bidirectional two-base bipolar junction transistor operation, circuits, and systems with collector-side base driven
Methods, systems, circuits, and devices for power-packet-switching power converters using bidirectional bipolar transistors (BTRANs) for switching. Four-terminal three-layer BTRANs provide substantially identical operation in either direction with forward voltages of less than a diode drop. BTRANs are fully symmetric merged double-base bidirectional bipolar opposite-faced devices which operate under conditions of high non-equilibrium carrier concentration, and which can have surprising synergies when used as bidirectional switches for power-packet-switching power converters. BTRANs are driven into a state of high carrier concentration, making the on-state voltage drop very low.
1. A method for switching a power semiconductor device which includes first emitter/collector and base contact regions on a first surface of a semiconductor die, and second emitter/collector and base contact regions on a second surface of the die; wherein the emitter/collector regions both have a first conductivity type, and the base contact regions and the semiconductor die all have a second conductivity type; comprising the steps:
in the ON state, when an external voltage difference applied between the first and second emitter/collector regions has a polarity such that the first and second emitter/collector regions can act as collector and emitter respectively, flowing base current through the first base contact region, but substantially not through the second base contact region; and
in the OFF state, not flowing external current through either of the base contact regions;
whereby bidirectional switching is achieved with an on-state voltage drop which is less than a diode drop between the semiconductor die and a respective one of the emitter/collector regions.
2. The method of claim 1 , wherein the semiconductor die is silicon.
3. The method of claim 1 , wherein the step of flowing current through the base contact region draws current from the base contact region.
4. The method of claim 1 , wherein the step of flowing current through the base contact region supplies current to the base contact region.
5. The method of claim 1 , further comprising, in the OFF state, floating one of the base contact regions.
6. The method of claim 1 , further comprising, in the ON state, conducting current as a diode, before the step of flowing base current.
7. A method for switching a power semiconductor device which includes distinct first and second first-conductivity-type emitter/collector regions which are not electrically connected together except through the semiconductor die itself and also includes distinct first and second second-conductivity-type base contact regions which are not electrically connected together except through the semiconductor die itself, the emitter/collector regions and the base contact regions all lying within two surfaces of a common semiconductor die, comprising:
in the ON state, when the applied voltage polarity is such that the first emitter/collector region, on a first of said surfaces, can act as the collector of, and the second emitter/collector region on a second of said surfaces can act as the emitter of, a bipolar transistor, driving the first base contact toward a voltage different from the first emitter/collector region by flowing base current through the first base contact region, on said first surface, while NOT flowing base current through the second base contact region, on said second surface; and
in the OFF state, floating at least one of the base contact regions, while not applying external current to either of the base contact regions;
whereby bidirectional switching is achieved with an on-state voltage drop which is less than a diode drop between the semiconductor die and a respective one of the emitter/collector regions.
8. The method of claim 7 , wherein the semiconductor die is silicon.
9. The method of claim 7 , wherein the step of flowing current through the base contact region draws current from the base contact region.
10. The method of claim 7 , wherein the step of flowing current through the base contact region supplies current to the base contact region.