Variable resistance to reduce gate votlage oscillations in gallium nitride transistors

1. A semiconductor transistor device, comprising:

a GaN transistor including a drain, a gate, and a source, the GaN transistor having a driving voltage applied across the gate and the source and configured to switch between an on-voltage associated with an on-state of the GaN transistor and an off-voltage associated with an off-state of the GaN transistor, wherein the driving voltage oscillates in response to a transition between the on-state and the off-state, and the driving voltage oscillations have a resonance frequency higher than a switching frequency of the driving voltage; and

a variable gate-source resistor connected between the gate and the source and having a variable resistance that varies in response to changes in the driving voltage when switching between the on-state and the off-state of the GaN transistor,

wherein the variable gate-source resistor includes a resistive dielectric region with a resistivity that varies directly with the driving voltage of the GaN transistor and indirectly with a driving frequency of the driving voltage.

2. The semiconductor transistor device of claim 1 , wherein the variable resistance varies directly with a magnitude of the driving voltage within a switching frequency range of the switching.

3. The semiconductor transistor device of claim 2 , wherein the variable resistance varies within a range corresponding to a driving voltage range between the on-voltage and the off-voltage.

4. The semiconductor transistor device of claim 1 , wherein the driving voltage switches at a switching frequency, and oscillates in response to a transition between the on-state and the off-state with a resonance frequency higher than the switching frequency, and further wherein the variable gate-source resistor is configured to filter the driving voltage within the resonance frequency.

5. The semiconductor transistor device of claim 1 , further comprising a gate resistor connected at the gate of the GaN transistor.

6. The semiconductor transistor device of claim 5 , wherein a resistance value of the gate resistor varies directly with a driving frequency of the driving voltage.

7. The semiconductor transistor device of claim 1 , wherein the variable gate-source resistor is configured to maintain the driving voltage oscillations relative to a threshold voltage of the GaN transistor to prevent turn-off of the GaN transistor during the on-state, or turn-on of the GaN transistor during the off-state.

8. A semiconductor transistor device, comprising:

a GaN transistor including a drain, a gate, and a source, the GaN transistor having a driving voltage applied across the gate and the source that switches between an on-voltage associated with an on-state of the GaN transistor and an off-voltage associated with an off-state of the GaN transistor, wherein the driving voltage oscillates in response to a transition between the on-state and the off-state, the driving voltage oscillations have a resonance frequency higher than a switching frequency of the driving voltage; and

a variable gate-source resistor connected between the gate and the source, the variable gate-source resistor including a resistive dielectric region with a resistivity that varies directly with the driving voltage of the GaN transistor and indirectly with a driving frequency of the driving voltage and thereby provides a low-pass filter that filters the driving voltage oscillations at the resonance frequency and during a transition between the off-state and the on-state.

9. The semiconductor transistor device of claim 8 , wherein a resistance value of the variable gate-source resistor is matched to a driving voltage range of the driving voltage, and reaches a maximum value at the on-voltage and a minimum value at the off-voltage.

10. The semiconductor transistor device of claim 8 , wherein the variable gate-source resistor is configured to pull the driving voltage oscillations to the off-voltage following a transition between the on-state and the off-state.

11. The semiconductor transistor device of claim 8 , further comprising a gate resistor connected at the gate of the GaN transistor.

12. The semiconductor transistor device of claim 11 , wherein a resistance of the gate resistor varies directly with a driving frequency of a driving voltage of the GaN transistor.

13. A semiconductor transistor device, comprising:

a GaN transistor including a drain, a gate, and a source, the GaN transistor having a driving voltage applied across the gate and the source and configured to switch with a switching frequency between an on-voltage associated with an on-state of the GaN transistor and an off-voltage associated with an off-state of the GaN transistor, the driving voltage oscillating in response to a transition between the on-state and the off-state, the driving voltage oscillations having a resonance frequency higher than the switching frequency; and

a variable gate-source resistor connected between the gate and the source, the variable gate-source resistor including a resistive dielectric region with a resistivity that varies indirectly with a driving frequency of the driving voltage and thereby provide a low-pass filter that filters the driving voltage oscillations at the resonance frequency.

14. The semiconductor transistor device of claim 13 , wherein the variable gate-source resistor has a resistance value that varies directly with the driving voltage.

15. The semiconductor transistor device of claim 13 , wherein the variable gate-source resistor is configured to maintain the driving voltage oscillations relative to a threshold voltage of the GaN transistor to prevent turn-off of the GaN transistor during the on-state, or turn-on of the GaN transistor during the off-state.