Low noise figure (NF) and gain flatness over wide frequency band are critical Low Noise Amplifier (LNA) performance parameters in high frequency applications. This paper presents a low-power, cascode feedback compound Sziklai pair LNA operating across 3.4 GHz-39.82 GHz frequency, making it suitable for Ultra-Wideband (UWB) and lower millimeter-wave (mmWave) applications in RF front-end systems. By leveraging a cascode feedback structure with NMOS Sziklai pair and complementary Sziklai pair, the proposed LNA achieves low input and output impedances, leading to improved broadband performance. A V Ref impedance tuning circuit (ITC) is employed to tune the gain and other parameters, further enhancing gain and overall performance. Active bias is used to provide appropriate DC bias to the transistors, which strengthens current feedback and mitigates narrowband limitations. By using a cascode feedback structure with lower transconductance transistors, power consumption is significantly reduced. Simulations performed in CMOS 180nm process shows peak voltage gain of 19.51 dB with a bandwidth of 36.42 GHz and peak current gain of 39.87 dB. These results represent substantial improvements compared to the conventional PMOS Sziklai LNA approach, with nearly double the voltage gain and four times the current gain. Furthermore, the LNA exhibits NF of 0.343 dB at 10 GHz, input third-order intercept point (IIP3) of 1.5 dBm, and chip area of 267.96 μm 2 . The power consumption is 49.28 μW from a 1.5 V DC supply, representing an 84.11% reduction compared to the PMOS Sziklai LNA. The proposed LNA also addresses the shortcomings of high-power consumption, low phase margin, and high harmonic distortions of PMOS Sziklai LNAs and low gain, narrow bandwidth, and high NF of Darlington RF cascode Feedback amplifier.
Arshad et al. (Fri,) studied this question.