Qorvo US, Inc.

Rf Micro Devices, Inc.

Jing Zhang

Brian G Moser

Peter J Zampardi

Thomas James Rogers

Dheeraj Mohata

Robert Saxer

A transistor includes a sub-collector, a base, a collector between the sub-collector and the base, and an emitter on the base opposite the collector. The collector includes a first region adjacent to the base and a second region between the first region and the sub-collector. The first region has a graduated doping profile such that a doping concentration of the first region decreases in proportion to a distance from the base. The second region has a substantially constant doping profile. By providing the collector with a doping profile as described, the linearity of the transistor is significantly improved while maintaining the radio frequency (RF) gain thereof.

Heterojunction bipolar transistor architecture

The present disclosure relates to heterojunction bipolar transistors for improved radio frequency (RF) performance. In this regard, a heterojunction bipolar transistor includes a base, an emitter, and a collector. The base is formed over the collector such that a base-collector junction is formed between the base and the collector. The base-collector junction is configured to become forward-biased at a first turn-on voltage. The emitter is formed over the base such that a base-emitter junction is formed between the base and the emitter. The base-emitter junction is configured to become forward-biased at a second turn-on voltage, as opposed to the first turn-on voltage. Notably, the second turn-on voltage is lower than the first turn-on voltage.

Heterojunction bipolar transistors for improved radio frequency (RF) performance

A heterojunction bipolar transistor includes a base mesa, an emitter assembly formed over the base mesa, and a base contact. The emitter assembly includes multiple circular sectors. Each circular sector is spaced apart from one another such that a sector gap is formed between radial sides of adjacent circular sectors. The base contact, which is formed over the base mesa, has a central portion and multiple radial members. Each radial member extends outward from the central portion of the base contact along a corresponding sector gap. As such, each of the circular sectors of the emitter assembly is separated by a radial member of the base contact. The number of circular sectors may vary from one embodiment to another. For example, the emitter assembly may have three, four, six, or more circular sectors.

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Jing Zhang