Integrated level shifter
GaN-based half bridge power conversion circuits employ control, support and logic functions that are monolithically integrated on the same devices as the power transistors. In some embodiments a low side GaN device communicates through one or more level shift circuits with a high side GaN device. Both the high side and the low side devices may have one or more integrated control, support and logic functions. Some devices employ electro-static discharge circuits and features formed within the GaN-based devices to improve the reliability and performance of the half bridge power conversion circuits.
1. A level shift circuit comprising:
a GaN-based level shift transistor, comprising:
a gate connected to a gate terminal,
a drain connected to a drain terminal, and
a source connected to a source terminal,
wherein the level shift transistor is configured to receive an input referenced to a ground at the gate terminal and to generate an output at the drain terminal, wherein the output is referenced to a floating voltage.
2. The level shift circuit of claim 1 , further comprising an electronically conductive element between the source terminal and a ground.
3. The level shift circuit of claim 1 , further comprising:
a first conductive element connected between the drain terminal and a floating power supply; and
a first pull up transistor connected between the drain terminal and the floating power supply.
4. The level shift circuit of claim 1 , wherein the level shift transistor is configured to receive a pulsed input signal, and wherein a duration of one or more pulses of the pulsed input signal is less than 500 nanoseconds.
5. The level shift circuit of claim 1 , wherein the level shift transistor is configured to receive a pulsed input signal, and wherein a duration of one or more pulses of the pulsed input signal is less than 200 nanoseconds.
6. The level shift circuit of claim 1 , wherein the level shift transistor is configured to receive a pulsed input signal, and wherein a duration of one or more pulses of the pulsed input signal is less than 100 nanoseconds.
7. The level shift circuit of claim 1 , wherein the level shift transistor is configured to receive a pulsed input signal, and wherein a duration of one or more pulses of the pulsed input signal is less than 75 nanoseconds.
8. The level shift circuit of claim 1 , wherein a channel width of the level shift transistor is less than 100 microns.
9. The level shift circuit of claim 1 , wherein a channel width of the level shift transistor is less than 50 microns.
10. The level shift circuit of claim 1 , wherein a channel width of the level shift transistor is less than 10 microns.
11. The level shift circuit of claim 1 , wherein a channel width of the level shift transistor is less than 5 microns.
12. The level shift circuit of claim 1 , wherein the level shift transistor is configured to conduct not more than 2 milliamps.
13. The level shift circuit of claim 1 , wherein the level shift transistor is rated for 650V.
14. The level shift circuit of claim 1 , wherein the level shift transistor has less than 25 picocoulombs of output charge (Qoss).
15. The level shift circuit of claim 1 , wherein the level shift transistor includes a source ohmic contact area connected to a source terminal, wherein the source terminal is connected to a metal pad that is adjacent to the source terminal, and wherein the metal pad has an area greater than 100 times area of the source ohmic contact.
16. The level shift circuit of claim 1 , wherein the level shift transistor includes a drain ohmic contact area connected to a drain terminal, and the drain terminal is connected to a metal pad that is that is adjacent to the source terminal, and wherein the metal pad has an area greater than 100 times area of the drain ohmic contact.
17. The level shift circuit of claim 16 , further comprising a conductive shield underneath the metal pad.
18. The level shift circuit of claim 17 , wherein the conductive shield is referenced to the floating supply.
19. The level shift circuit of claim 17 , wherein the conductive shield is referenced to ground.
20. The level shift circuit of claim 1 , wherein the level shift transistor comprises a source area and a drain area and the source area does not encircle the drain area.