A Coupled-RTWO-Based Subharmonic Receiver Front End for 5G E-Band Backhaul Links in 28-nm Bulk CMOS

Abstract

An E-band direct-conversion subharmonic receiver (SHRX) is designed exploring a coupled-rotary-traveling-wave-oscillator-based (coupled-RTWO-based) architecture. Distributed oscillators are leveraged to generate N=8 differential phases at fLO=fRF/4. Current-mode passive mixers (MXs) are adopted to enable <1-V supply operation and greatly simplify the layout. An inductively degenerated neutralized common source (DCS) low-noise amplifier (LNA) is embedded in a fourth-order transformer-based matching network to allow broadband impedance scaling and high reverse isolation. Implemented in a 28-nm bulk CMOS technology without ultra-thick top metal option, the realized prototype outperforms prior reported CMOS designs in terms of phase noise, figure of merit (FOM), and tuning range. The SHRX front end achieves 8.3-dB noise figure (NF), 12.5 GHz-3-dB RF bandwidth (BW), and-25-dBm ICP1 dB, while consuming <100 mW.