PNP AlGaAs/GaAs HBT low noise amplifiers

This paper describes the performance of PNP AlGaAs/GaAs HBT-based low noise amplifiers. A 2 GHz narrow-band noise matched LNA achieves a min, NF=2.2 dB and an associated gain of 9.3 dB while consuming only 4 mW through a -2 V supply. A DC-4.5 GHz wideband direct-coupled LNA achieves 20 dB gain, and NFs of 2.0, 2.4, and 2.8 dB at 1, 2, and 4 GHz, respectively. The GaAs PNP HBTs of this work employ an exponentially graded base doping profile to enhance the device f/sub T/ and improve the high frequency NF performance. The resulting PNP HBT LNAs obtain noise figure-bandwidth performance which is better than Si-BJT LNAs, and comparable to NPN HBT LNAs for frequencies up to 4 GHz.