A 50–70.9-GHz LNA With Configured Coupled Transformer Achieving Sub-4 dB NF and 298.6-GHz GBW for 5GNR-FR2-2 and SATCOM

This article presents a 50–70.9-GHz low-noise amplifier (LNA) with a configured coupled transformer (CCT). Millimeter-wave (mm-wave) signals at the gate and source are out of phase due to the opposite coupling polarities of the input-to-gate and input-to-source, thereby enabling <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{m}$</tex-math> </inline-formula>-boosting. Meanwhile, the thermal noise of the first-stage MOS is fed back inversely from the source to the gate, achieving noise self-reduction. According to theoretical analysis, under the above conditions, source-to-gate coupling weakens the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{m}$</tex-math> </inline-formula>-boosting and noise-reduction effects. Hence, the CCT structure is proposed to employ coupling cancellation, minimizing this specific coupling in a three-winding transformer. The source-to-gate coupling in the input CCT network is suppressed to achieve wideband simultaneous noise and input matching. Furthermore, neutralized <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${\textrm {G}}_{m}$</tex-math> </inline-formula> cells and fourth transformer-based magnetically coupled resonators (MCRs) are utilized to provide high gain, good stability, and wideband interstage matching. Verified in a conventional 40-nm bulk CMOS process, the proposed LNA achieves 3.5 dB minimum NF and 298.6-GHz gain-bandwidth (GBW), while consuming 33 mW. The input-matching range covers 47–73.4 GHz. The input P1dB (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text {IP}_{\text {1 dB}}$</tex-math> </inline-formula>) is measured as −11.8 to −17.5 dBm in the 50–72-GHz frequency range. The proposed LNA supports a 4 Gb/s 256-QAM modulation signal with −30.8-dB error vector magnitude (EVM) at 59 GHz. Benefiting from the CCT, the proposed LNA demonstrates the highest figure of merit (FoM) compared to state-of-the-art mm-wave LNAs.