A Study of second-order nonlinearity in a single-ended RF input Gilbert mixer

This paper investigates the second-order input intercept point (IIP₂) of a 2.6 GHz Gilbert mixer RFIC with a signal-ended RF input. The 2.6 GHz Gilbert mixer is designed and implemented in 0.15-¿m InGaAs pseudomorphic high electron mobility transistor (PHEMT) foundry process. The IIP₂ of the single-ended RF input Gilbert mixer is degraded by 12 dB due to unbalanced RF signal when compared to the fully differential RF input Gilbert mixer. The adaptive biasing in a switching stage of a Gilbert mixer is used to compensate the IIP₂. The proposed technique improves the IIP₂ by 19 dB without at cost of the conversion gain.