A K_u-Band RF Front-End Employing Broadband Impedance Matching with 3.5 dB NF and 21 dB Conversion Gain in 45-nm CMOS Technology

This paper presents a Ku-band RF receiver front-end with broadband impedance matching and amplification. The major building blocks of the proposed receiver front-end include a wideband low-noise amplifier (LNA) employing a cascade of resistive feedback inverter (RFI) and transformer-loaded common source amplifier, a down-conversion mixer with push-pull transconductor and complementary LO switching stage, and an output buffer. Push-pull architecture is employed extensively to maximize the power efficiency, bandwidth, and linearity. The proposed two-stage LNA employs the stagger-tuned frequency response in order to extend the RF bandwidth coverage. The input impedance of RFI is carefully analyzed, and a wideband input matching circuit incorporating only a single inductor is presented along with useful equivalent impedance matching models and detailed design analysis. The prototype chip was fabricated in 45-nm CMOS technology and dissipates 78 mW from a 1.2-V supply while occupying chip area of 0.29 mm2. The proposed receiver front-end provides 21 dB conversion gain with 7 GHz IF bandwidth, 3.5 dB NF, 15.7 dBm IIP3 while satisfying <10 dB input matching over the whole input band.