Pulsed level shift and inverter circuits for GaN devices
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. Various embodiments of level shift circuits and their inventive aspects are disclosed.
1. A level shift circuit, comprising:
a first inverter circuit comprising:
a first input terminal,
a first output terminal,
a first GaN-based transistor having a gate coupled to the first input terminal, a drain coupled to the first output terminal, and a source coupled to a ground, and
a first pull up device coupled between the drain of the first GaN-based transistor and a power supply; and
a second inverter circuit comprising:
a second input terminal,
a second output terminal,
a second GaN-based transistor having a gate coupled to the second input terminal, a drain coupled to the second output terminal, and a source coupled to the ground, and
a second pull up device coupled between the drain of the second GaN-based transistor and the power supply,
wherein the first pull up device comprises a third GaN-based transistor having a gate driven with a voltage based on the voltage at the second output terminal, and wherein the first, second, and third GaN-based transistors are of the same conductivity type.
2. The circuit of claim 1 , wherein the gate of the third GaN-based transistor is coupled to an output of an inverter circuit, and wherein an input of the inverter circuit is coupled to the second output terminal.
3. The circuit of claim 2 , wherein the inverter circuit comprises an inverter, and the input of the inverter is coupled to the second output terminal by one or more additional GaN-based transistors.
4. The circuit of claim 1 , further comprising a second pull up device coupled between the drain of the first GaN-based transistor and the power supply.
5. The circuit of claim 4 , wherein the second pull up device conducts current passively.
6. The circuit of claim 4 , further comprising a third pull up device coupled between the drain of the first GaN-based transistor and the power supply.