Radio frequency transistor amplifiers having engineered instrinsic capacitances for improved performance
AssigneeWolfspeed, Inc.
InventorsQianli Mu, Zulhazmi Mokhti, Jia Guo, Scott Sheppard
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Abstract
Gallium nitride based RF transistor amplifiers include a semiconductor structure having a gallium nitride based channel layer and a gallium nitride based barrier layer thereon, and are configured to operate at a specific direct current drain-to-source bias voltage. These amplifiers are configured to have a normalized drain-to-gate capacitance at the direct current drain-to-source bias voltage, and to have a second normalized drain-to-gate capacitance at two-thirds the direct current drain-to-source bias voltage, where the second normalized drain-to-gate capacitance is less than twice the first normalized drain-to-gate capacitance.
Claims17
A radio frequency (“RF”) transistor amplifier, comprising:
- a semiconductor structure that includes a gallium nitride based channel layer and a gallium nitride based barrier layer that has a higher bandgap than the gallium nitride based channel layer on the gallium nitride based channel layer;
- a source contact on the gallium nitride based barrier layer;
- a drain contact on the gallium nitride based barrier layer;
- and
- a gate contact on the gallium nitride based barrier layer between the source contact and the drain contact,
- wherein the RF transistor amplifier is configured to operate at a first direct current drain-to-source bias voltage,
- wherein the RF transistor amplifier is configured to have a normalized drain-to-source capacitance that maintains at least 85% symmetry for a range of drain-to-source voltages about the first direct current drain-to-source bias voltage that is equal to 50% of the first direct current drain-to-source bias voltage, and
- wherein a normalized drain-to-gate capacitance response of the RF transistor amplifier varies by less than a factor of four for all values of the drain-to-source voltage that are between one half the first direct current drain-to-source bias voltage and twice the first direct current drain-to-source bias voltage.
A radio frequency (“RF”) transistor amplifier, comprising:
- a semiconductor structure that includes a gallium nitride based channel layer and a gallium nitride based barrier layer that has a higher bandgap than the gallium nitride based channel layer on the gallium nitride based channel layer;
- a source contact on the gallium nitride based barrier layer;
- a drain contact on the gallium nitride based barrier layer;
- and
- a gate contact on the gallium nitride based barrier layer between the source contact and the drain contact,
- wherein the RF transistor amplifier is configured to operate at a first direct current drain-to-source bias voltage,
- wherein the RF transistor amplifier is configured to have a normalized drain-to-source capacitance that maintains at least 85% symmetry for a range of drain-to-source voltages about the first direct current drain-to-source bias voltage that is equal to 50% of the first direct current drain-to-source bias voltage, and
- wherein the RF transistor amplifier is configured so that a normalized drain-to-gate capacitance response varies by less than 100% for drain-to-source voltages in a range from the first direct current drain-to-source bias voltage to 20 volts below the first direct current drain-to-source bias voltage.
Dependencies are inferred from the claim text.