A Compact Wideband Simultaneous Noise and Input Matching Method Based on Three-Coil Transformer With Capacitor Assistance for LNA Design

A method for achieving wideband simultaneous noise and input matching (SNIM) based on traditional higher order networks has been analyzed and improved through capacitor-assisted techniques. Subsequently, a new wideband SNIM approach, utilizing a three-coil transformer combined with capacitor assistance, is proposed. Without altering the conventional topological structure, the introduction of the coupling factor significantly reduced the chip area and the noise contribution from passive components, thereby lowering the overall noise figure (NF). To validate the design, a C-band two-stage current-reused low-noise amplifier (LNA) was designed with a 55-nm CMOS process. The measurement results indicate that S11 is below −10dB across a wideband of 2.5–8.5 GHz. A power gain of 24.6dB is achieved at 5 GHz with −3-dB bandwidth of 4.8 GHz. The noise matching discrepancy (NF-NF_min) remains 0.15dB within the band range of 4.2–8.5 GHz, and NF maintains below 2dB, while the power consumption is only 9.1 mW.