Radio frequency transistor amplifiers having engineered intrinsic capacitances for improved performance

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 first normalized drain-to-gate capacitance at the first direct current drain-to-source bias voltage, and to have a second normalized drain-to-gate capacitance at two-thirds the first direct current drain-to-source bias voltage, and
• wherein the second normalized drain-to-gate capacitance is less than twice the first normalized drain-to-gate capacitance.