5.5 GHz Low Voltage and High Linearity RF CMOS Mixer Design

A CMOS mixer was design with a new circuit scheme to realize low voltage and high linearity simultaneously. A double balanced Gilbert cell was adopted as the basic topology and TSMC 0.18 mum 1P6M CMOS process was employed for the on-chip RF circuit fabrication. The proposed new circuit scheme consists of LC-tanks as a capacitively coupled resonator for low voltage and multi-stage parallel RC networks for linearity improvement. Furthermore, multi-gated structure is applied at the RF input as a transconductance amplifier to enhance conversion gain and linearity. The new circuit scheme enables a successful low voltage operation at 1-V for 0.18 mum technology, The measured circuit performance demonstrates superior linearity with IIP3 of 11 dBm and P1dB of 2.2 dBm. The conversion gain can be maintained at 8.1 dB in a wide frequencies of 5 GHz to 6.8 GHz.