A Compact Millimeter-Wave Reconfigurable Dual-Band LNA With Image-Rejection in 28-nm Bulk CMOS for 5G Applications

This article presents a reconfigurable dual-band low noise amplifier (LNA) for 5G millimeter-wave (mmWave) applications in the TSMC 28-nm bulk CMOS process. The reconfigurable LNA is based on a two-stage amplifier design with switchable triple-coupled transformer and capacitor technologies applied to the inter-stage and output matching networks. The switchable triple-coupled transformer can change the self-inductance of the transformer coils by tuning the magnetic flux entering the coils. To suppress the image frequency interference, magnetic–electric hybrid coupling is integrated into the inter-stage matching network, which introduces a transmission zero, resulting in a high image rejection ratio. The measured result shows that the low band has a peak gain of 18.1 dB with a 3-dB bandwidth of 23.8–33.5 GHz, and the high band has a peak gain of 18.9 dB with a 3-dB bandwidth of 34.4–41.4 GHz. The image rejection ratio is better than 32.7 dBc with an intermediate frequency of 8 GHz. The measured NF is better than 3.5 dB at both bands. The IP1dB is <tex-math notation="LaTeX">$-$</tex-math> 19 to <tex-math notation="LaTeX">$-$</tex-math> 15.1/ <tex-math notation="LaTeX">$-$</tex-math> 18.5 to <tex-math notation="LaTeX">$-$</tex-math> 15.2 dBm in the low/high band. The fabricated LNA has a very compact core size of 0.09 mm <tex-math notation="LaTeX">²</tex-math> , and the total power consumption is only 14 mW.