Low Noise Group Delay Equalization Technique for UWB InGaP/GaAs HBT LNA

This letter describes an ultra-wideband (UWB) LNA designed with the aim of achieving both flat group delay variation and a low noise characteristic. Negative group delay (NGD) circuits are good candidates for compensating the group delay variation; however, they have inherent resistances that deteriorate the noise figure (NF). Therefore, an NGD circuit is applied to the latter part of a prototype amplifier. Similarly, a noise matching circuit is applied to the group-delay-equalized amplifier with consideration for its effect on the group delay variation. The LNA with an NGD circuit and a noise matching circuit is fabricated on an InGaP/GaAs MMIC substrate. The fabricated LNA achieved a group delay variation of 11.2 ps, a NF of 1.95-3.54 dB, a maximum gain of 12.3 dB, and a gain variation of 1.1 dB in the UWB band (3.1-10.6 GHz).