Systems, circuits, devices, and methods with bidirectional bipolar transistors
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 power-packet-switching power converter, comprising:
a plurality of phase legs which each include two bidirectional switches which can connect a respective external line to either side of a link inductor which is paralleled by a capacitor, each said bidirectional switch comprising:
first and second first-conductivity-type emitter regions on opposing faces of a second-conductivity-type semiconductor mass, and
first and second second-conductivity-type base contact regions, in proximity to said first and second emitter regions respectively;
control circuitry which, repeatedly, turns on a selected one or two of said bidirectional switches to drive energy from one or more input lines into said inductor, and then turns off all of said switches to disconnect said inductor, and then turns on a different selected one or two of said bidirectional switches to drive energy from said inductor onto one or two output lines; and
a drive circuit which, when the control circuitry selects one of said bidirectional switches for turn-on, drives the first and second base contact regions of that switch differently, to thereby permit current to flow in a predetermined direction between said first and second emitter regions on the opposing faces of said respective semiconductor mass;
wherein the drive circuit applies sufficient current between to the selected base contact region and at least one said emitter region to generate a nonequilibrium carrier concentration, in the interior of said semiconductor mass, which is more than thirty times as great as the off-state equilibrium majority carrier concentration in the semiconductor mass, to thereby lower the voltage drop across the switch.
2. The power-packet-switching power converter of claim 1 , wherein, when one said bidirectional switch is conducting in a first direction from one said face, the emitter regions on the opposing face act as collector regions.
3. The power-packet-switching power converter of claim 1 , wherein said bidirectional switches are driven in a regime of high carrier densities.
4. The power-packet-switching power converter of claim 1 , wherein the second-conductivity-type base contact regions in said bidirectional switches are more highly doped than the respective second-conductivity-type semiconductor mass.
5. The power-packet-switching power converter of claim 1 , said bidirectional switches further comprising a thin layer of tunnel oxide between each said first-conductivity-type emitter region and the respective second-conductivity-type semiconductor mass.
6. The power-packet-switching power converter of claim 1 , said bidirectional switches further comprising a thin layer of tunnel oxide between each said first-conductivity-type emitter region and a respective emitter metallization.
7. The power-packet-switching power converter of claim 1 , wherein emitter-base junctions of said bidirectional switches are heterojunction.
8. The power-packet-switching power converter of claim 1 , wherein the first-conductivity-type emitter regions of said bidirectional switches are amorphous silicon, and the respective second-conductivity-type semiconductor mass is substantially monocrystalline silicon.
9. The power-packet-switching power converter of claim 1 , wherein the first-conductivity-type emitter regions of said bidirectional switches are polycrystalline silicon, and the respective second-conductivity-type semiconductor mass is substantially monocrystalline silicon.
10. The power-packet-switching power converter of claim 1 , said bidirectional switches further comprising oxide-filled trenches between each said first-conductivity-type emitter region and respectively adjacent second-conductivity-type base contact regions.
11. The power-packet-switching power converter of claim 1 , each said bidirectional switch further comprising a respective edge termination structure which comprises a first-conductivity-type region in a second-conductivity-type region.
12. A power-packet-switching power converter, comprising:
a plurality of phase legs which each include two bidirectional switches which can connect a respective external line to either side of a link inductor which is paralleled by a capacitor, each said bidirectional switch comprising:
first and second first-conductivity-type emitter regions on opposing faces of a second-conductivity-type semiconductor mass, and
first and second second-conductivity-type base contact regions, in proximity to said first and second emitter regions respectively;
control circuitry which, repeatedly, turns on a selected one or two of said bidirectional switches to drive energy from one or more input lines into said inductor, and then turns off all of said switches to disconnect said inductor, and then turns on a different selected one or two of said bidirectional switches to drive energy from said inductor onto one or two output lines; and
a drive circuit which, when the control circuitry selects one of said bidirectional switches for turn-on, drives the first and second base contact regions of that switch differently, to thereby permit current to flow in a predetermined direction between said first and second emitter regions on the opposing faces of said respective semiconductor mass;
wherein the drive circuit applies sufficient current between the selected base contact region and at least one said emitter region to drive the beta down to less than one-quarter of its small-signal value.
13. The power-packet-switching power converter of claim 12 , wherein, when one said bidirectional switch is conducting in a first direction from one said face, the emitter regions on the opposing face act as collector regions.
14. The power-packet-switching power converter of claim 12 , wherein said bidirectional switches are driven in a regime of high carrier densities.
15. The power-packet-switching power converter of claim 12 , wherein the second-conductivity-type base contact regions in said bidirectional switches are more highly doped than the respective second-conductivity-type semiconductor mass.
16. The power-packet-switching power converter of claim 12 , said bidirectional switches further comprising a thin layer of tunnel oxide between each said first-conductivity-type emitter region and the respective second-conductivity-type semiconductor mass.
17. The power-packet-switching power converter of claim 12 , said bidirectional switches further comprising a thin layer of tunnel oxide between each said first-conductivity-type emitter region and a respective emitter metallization.
18. The power-packet-switching power converter of claim 12 , wherein emitter-base junctions of said bidirectional switches are heterojunction.
19. The power-packet-switching power converter of claim 12 , wherein the first-conductivity-type emitter regions of said bidirectional switches are amorphous silicon, and the respective second-conductivity-type semiconductor mass is substantially monocrystalline silicon.
20. A power-packet-switching power converter, comprising:
a plurality of phase legs which each include two bidirectional switches which can connect a respective external line to either side of a link inductor which is paralleled by a capacitor, each said bidirectional switch comprising:
first and second first-conductivity-type emitter regions on opposing faces of a second-conductivity-type semiconductor mass, and
first and second second-conductivity-type base contact regions, in proximity to said first and second emitter regions respectively;
control circuitry which, repeatedly, turns on a selected one or two of said bidirectional switches to drive energy from one or more input lines into said inductor, and then turns off all of said switches to disconnect said inductor, and then turns on a different selected one or two of said bidirectional switches to drive energy from said inductor onto one or two output lines; and
a drive circuit which, when the control circuitry selects one of said bidirectional switches for turn-on, drives the first and second base contact regions of that switch differently, to thereby permit current to flow in a predetermined direction between said first and second emitter regions on the opposing faces of said semiconductor mass;
wherein the drive circuit applies sufficient current between the selected base contact region and at least one said emitter region to generate a nonequilibrium carrier concentration, in the interior of said semiconductor mass, which is more than thirty times as great as the off-state equilibrium majority carrier concentration, to thereby lower the voltage drop across the switch to less than half a diode drop.