Improved efficiency, IP3-bandwidth and robustness of a microwave Darlington amplifier using 0.5/spl mu/m ED PHEMT and a new circuit topology

This paper reports on the first results of a self-biased e-mode PHEMT Darlington amplifier. The e-mode PHEMTs enable a FET Darlington implementation while a new Darlington active bias topology reduces bias variation over temperature and supply, and improves overall efficiency by reducing supply operation. A 3.3V-75mA amplifier achieves a BW of 0.1-14GHz, 12.3dB gain, NF of 3.5dB, IP3 and P1dB of 33.1dBm and 16dBm @ 2GHz, respectively. A 5V-75mA amplifier achieves a 0.1-10 GHz BW, 20.2 dB gain, NF of 2.9 dB, IP3 and P1dB of 34.2dBm and 21.8dBm @ 2 GHz, respectively. The new PHEMT Darlington amplifier design enables a factor of 2 better IP3-bandwidth product and lower voltage operation capability compared to InGaP-based Darlington amplifiers.