Down-Conversion Mixer Using λ/4-TL-C-based Coupler and BSFB Technique for 28 GHz 5G NR

We report a low-voltage (V
DD
) and low-power (P
DC
) wideband CMOS down-conversion mixer with high conversion gain (CG) for 28 GHz 5G new radio (NR). Body-self-forward-bias (BSFB) technique, i.e., connection of the transconductance (gm)-stage transistors’ body to their drain via a large body resistance, is used for threshold voltage (V
th
) and V
DD
reduction, and substrate leakage suppression. CG and noise figure (NF) enhancement in the condition of the same (or even a lower) P
DC
is achieved because lower V
DD
and higher gm (due to larger bias current) are used. To achieve harmonic-suppression and near perfect coupling from the RF gm stage to the LO switch transistors, two λ/4 transmission-lines (TLs) in conjunction with two coupling capacitors (C
c
), named λ/4-TL-C-based coupler, are used. The mixer consumes 4.5 mW and achieves CG of 11.1±1.5 dB for 12.4-32 GHz (i.e., 3 dB bandwidth (f
3dB
) of 19.6 GHz), noise figure (NF) of 10.6 dB, and figure-of-merit (FOM) of 0.0193, one of the best results ever reported for millimeter-wave down-conversion mixers with f
3dB
greater than 10 GHz and P
DC
lower than 10 mW.