Ka -/ K -Band Frequency-Reconfigurable Single-Input Differential-Output Low-Noise Amplifier for 5G Applications

This letter describes the design, analysis, and performance measurements of a Ka -and K -band frequency-reconfigurable single-input differential-output (SIDO) low-noise amplifier (LNA) with a compact core size of 0.157 mm ^2 . At 28 and 39 GHz, respectively, the noise figures of the LNA were 2.8 and 4.4 dB; it had high differential gains of 20.1 and 14.9 dB. The proposed LNA was fabricated using the 65-nm CMOS process. The LNA includes a two-stage common-source (CS) buffer amplifier to achieve low noise and an active balun for converting single-ended signals into differential signals. Moreover, a substrate-shield-based inductor and tunable matching networks were used to achieve the frequency reconfiguration function of the LNA. The gain and phase imbalances were 0.3 and 0.2 dB, and 5.4 ^\circ and 6 ^\circ at 28 and 39 GHz, respectively. Compared with published multiband SIDO LNAs, the proposed amplifier achieved higher figures of merit (FoMs) of 3.52 and 1.77 while maintaining a compact core size. Therefore, the LNA is suitable for K -and Ka -band 5G communication applications.