Power amplifier modules including transistor with grading and semiconductor resistor

A power amplifier module comprising:

• a power amplifier on a substrate, the power amplifier including a bipolar transistor having a collector, a base, and an emitter, the collector having a doping concentration of at least 3×1016 cm−3 at an interface with the base, the collector also having a grading in which doping concentration increases away from the base;
• and
• a semiconductor resistor on the substrate, the semiconductor resistor including a resistive layer that includes the same material as a layer of the bipolar transistor.

A power amplifier module comprising:

• a power amplifier on a gallium arsenide substrate, the power amplifier including a heterojunction bipolar transistor having a collector, a base, and an emitter, the collector having a doping concentration of at least 3×1016 cm−3 at an interface with the base, the collector also having a grading in which doping concentration increases away from the base;
• and
• a semiconductor resistor on the gallium arsenide substrate, the semiconductor resistor including a resistive layer that includes the same material as a layer of the heterojunction bipolar transistor, and the resistive layer being disposed laterally from and being electrically isolated from the layer of the heterojunction bipolar transistor.

A power amplifier module comprising:

• a power amplifier on a gallium arsenide substrate, the power amplifier including a heterojunction bipolar transistor having a collector, a base, and an emitter, the collector having a doping concentration in a range from 5×1016 cm−3 to 9×1016 cm−3 at an interface with the base, the collector also having a grading in which doping concentration increases away from the base;
• and
• a semiconductor resistor on the gallium arsenide substrate, the semiconductor resistor including a plurality of differently doped gallium arsenide layers, the plurality of differently doped gallium arsenide layers include a resistive layer that includes the same material as a layer of the heterojunction bipolar transistor, and the resistive layer is disposed laterally from and is electrically isolated from the layer of the heterojunction bipolar transistor.