High-Gain High-Linearity Band-Switchable CMOS Mixer Using Multipath Active Superposition

This article presents a compact 27-/39-GHz band-switchable upconversion mixer with enhanced gain and linearity for 5G frequency range 2 (FR2) communications. The proposed mixer employs a Hartley high intermediate frequency (IF) superheterodyne architecture with integrated IF switch, enabling reconfigurable spectral through dynamic sideband suppression across dual 24–30- and 36–42-GHz bands. To address the degradation of gain and linearity in high-IF topology, the multipath active superposition (MPAS) is implemented in the proposed mixer. It demonstrates a 6-dB enhancement in conversion gain (CG) and a 3.5-dBm increase in output 1-dB compression point (OP ${}_{1\,\text {dB}}$ ) and third-order output intercept point (OIP3) relative to conventional mixers, effectively decoupling the inherent gain–linearity tradeoff. The proposed mixer is fabricated in 40-nm bulk CMOS technology, featuring a compact core area of merely 0.12 mm² while consuming 35.8 mW at 1-V supply voltage. It achieves 1.3-/0.8-dBm OP ${}_{1\,\text {dB}}$ and 10.9-/9.7-dBm OIP3 with 11-/9.6-dB CG at 26.5/38.5 GHz, respectively. The measured image rejection ratio (IRR) reaches the peak values of 36.7 and 32.8 dBc in the 27- and 39-GHz bands. Symmetrical layout enables better than 40-dBc LO-to-RF isolation. To the best of our knowledge, this work demonstrates the highest CG with competitive linearity in K-/Ka-bands upconversion mixers without RF output buffers.