A 0.3-15 GHz SiGe LNA with >1 THz Gain-Bandwidth Product

A wideband LNA with a frequency range of 0.3-15 GHz is introduced for space-based applications. The LNA achieves less than 2.2 dB noise figure (NF) at room temperature, with minimum measured NF of 1.8 dB and peak gain of 37.3 dB. To the authors' best knowledge, this is the lowest NF at this bandwidth, with the highest gain-bandwidth product (1.1 THz) reported to date. Moreover, the performance of the LNA was studied across temperature, down to 78 K. The NF improves considerably and achieves a record average value of 1 dB over the whole bandwidth at 78 K, with a minimum NF of 0.74 dB at 1 GHz. Additionally, the bandwidth and gain were enhanced at 78 K without degrading input or output matching. To compensate for small gain variations across temperature, a gain control technique is proposed, which yields more than 15 dB of gain control without breaking the feedback loop and without sacrificing power matching.