A Cascode-Feedback Wideband Low Noise Amplifier in 180nm CMOS using a Compound Sziklai Pair

Conventional Darlington CMOS LNAs suffer from low transconductance, degraded noise figure due to parasitic inductors and limited high-frequency gain. This paper proposes a compound Sziklai pair‑based low‑noise amplifier (LNA) employing a cascode feedback technique for ultra-wideband and lower millimetre-wave applications. The design replaces inductive feedback with resistive feedback to minimise parasitic loss, reduce chip area and improve stability, while the Sziklai pair enhances high-frequency performance, reduces base-emitter voltage and improves linearity over the Darlington LNAs. Cascode feedback structure combined with compound Sziklai pair further improves noise performance. A VRef impedance tuning circuit (ITC) with tuning resistor and tuning inductor is used to optimise the LNA parameters. Active bias provides appropriate DC bias to the transistors, which strengthens current feedback and mitigates narrowband limitations. Implemented in 180 nm CMOS, the design achieves a peak voltage gain of 19.51 dB, a bandwidth of 36.42 GHz, a noise figure of 0.343 dB and power consumption of 49.28 µW only. Compared with recent state-of-the-art CMOS LNAs, the proposed design achieves significantly lower noise figure and power consumption while preserving gain and bandwidth. To the best of our knowledge, no prior CMOS Sziklai pair‑based LNA design is reported with inductorless resistive feedback cascode topology for UWB and lower mmWave RF front-end applications.