A 0.1-to-4.3-GHz Variable-Gain Balun LNA With Dual-Path Noise-Canceling Technique

This article introduces a variable-gain low-noise amplifier (VG-LNA) designed for IoT applications. The VG-LNA utilizes a similar architecture to the gm-boost input topology to address input impedance matching degradation during gain adjustment. In addition, it incorporates a dual noise cancellation (NC) path to reduce thermal noise. Due to the differential output characteristics of this topology, this LNA can simultaneously realize the balun function. Fabricated using a 65-nm CMOS process and without ON-chip inductors, the VG-LNA occupies only 0.002 mm2 of the core area. The VG-LNA achieves a turntable voltage gain range of 4.1–20 dB, an IIP3 range of -5.3–6.2 dBm, and a noise figure (NF) range of 1.8–6.8 dB over a 3-dB bandwidth across 0.1–4.3 GHz.