Wideband CMOS Low-Noise Amplifier Using RC Feedback and Inductor for Resonance

In this study, we design a CMOS wideband low-noise amplifier (LNA) with staggered tuning technique. In a wideband LNA, a design technique that can secure the gain flatness using RC feedback and inductor for resonance is proposed. The common-source (CS) structure with an RC feedback and an inductor is analyzed using equivalent circuits, and it was verified that the gain could be flattened by adjusting the resonance frequency and the resistance of the RC feedback. In addition, a high-pass filter (HPF) structure and an adaptive bias circuit (ABC) are applied to obtain a reasonable noise figure (NF) and linearity in a wide frequency range. A designed wideband LNA is fabricated using 65-nm RFCMOS process. As a measured result, the 1-dB bandwidth is approximately 15.6GHz from 20.1 to 35.7GHz. The 3-dB bandwidth is measured at 18.4 GHz. In the range of 25–35 GHz, the NF is lower than 3.45 dB.