Active Cold-Load Gate Terminations in a 220 GHz Distributed Amplifier for Baseband Noise Figure Reduction in 35-nm InGaAs-mHEMT Technology

This study provides proofs of concepts of active gateterminations to a 220 GHz distributed amplifier (DA) in 35-nmInGaAs-mHEMT technology. The noise figure of the DA has asurge spanning the first 60 GHz, originating from a terminationresistor. The resistor has been replaced with an 85 K activecold-load (ACL) and a matched-cell (MC), a method inspiredby the work of Kevin W. Kobayashi et al. The NF has beenreduced by {3.3, 5.9} dB for a baseband bandwidth of 10 GHzand {1.8, 3,3} dB for bandwidth of 60 GHz, for the ACL andMC respectively, with a negligible impact on the input matchingand gain. The ACL demonstrates a a dip in IIP3 of 4 dB around20 GHz. It’s further proven that the MC makes it impossibleto simultaneously match the input and the output ports of theDA, implying further modifications outside the scope of thisproject are required. The ACL and MC increase the total powerconsumption by 58% and 73% respectively.