Enhanced linearity and efficiency of HBT power amplifiers for 5-GHz wireless-LANs

This paper describes two advanced techniques to enhance linearity and efficiency in HBT power amplifiers (PA) for 5-GHz wireless-LANs (W-LANs). The diode-based linearizing circuit successfully compensates the gain expansion of PAs operating at a low quiescent current. The output matching circuit consisting of on-chip MIM capacitors and bond wires effectively reduces the loss of the circuit as well as allowing the miniaturization of the PA module. The PA MMIC fabricated incorporating these techniques achieved an improvement in linear output power and PAE of 2.4 dBm and 4.8%, respectively, compared to our previous PA with the same device dimensions, and exhibited an output power of 22.1 dBm and a PAE of 27.3% at an EVM of 5%, measured with 54Mbps 64-QAM-OFDM signals at 5.25 GHz.