A Flicker Noise/IM3 Cancellation Technique for Active Mixer Using Negative Impedance

This paper presents an approach to simultaneously cancel flicker noise and IM3 in Gilbert-type mixers, utilizing negative impedances. For proof of concept, two prototype double-balanced mixers in 0.16- μm CMOS are fabricated. The first demonstration mixer chip was optimized for full IM3 cancellation and partial flicker noise cancellation; this chip achieves 9-dB flicker noise suppression, improvements of 10 dB for IIP3, 5 dB for conversion gain, and 1 dB for input P
_{1 dB}
while the thermal noise increased by 0.1 dB. The negative impedance increases the power consumption for the mixer by 16% and increases the die area by 8% (46 × 28 μm
²
). A second demonstration mixer chip aims at full flicker noise cancellation and partial IM3 cancellation, while operating on a low supply voltage (0.67 × V
_DD
); in this chip, the negative impedance increases the power consumption by 7.3% and increases the die area by 7% (50 × 20 μm
²
). For one chip sample, measurements show >10-dB flicker noise suppression within ±200% variation of the negative impedance bias current; for ten randomly selected chip samples, >11-dB flicker noise suppression is measured.