A Novel E-mode PHEMT Linearized Darlington Cascode Amplifier

This paper reports the first results of a new Darlington cascode topology implemented with 0.5mum E-mode PHEMTs. The Darlington cascode employs active self-bias and a linearizing Darlington cascode (DCAS) circuit for achieving robust bias and enhanced gain and IP3-bandwidth performance. The Darlington cascode achieves 12.5 dB gain with a 16 GHz 3-dB BW - a 60% BW improvement over the conventional Darlington. The DCAS obtains an IP3 of 29 dBm with a 13 GHz BW - an 80% improvement in IP3-BW over the conventional Darlington approach. These improvements have been obtained without significantly compromising NF, stability, or bias robustness. The new DCAS amplifier design can be applied to other semiconductor technologies and offers an approach for compacting high microwave performance into a small area without the use of distributed techniques