Design of A 2-3 GHz Down-Conversion Active Mixer With Improved Linearity

Abstract

A down-conversion active mixer with high linearity and low noise behavior for 2-3 GHz wireless local area networks (WLAN) applications is presented. This mixer is designed based on the RF-TSMC $0.18\ \mu\mathrm{m}$ CMOS technology. In order to suppress third order nonlinearity, a new fully differential Darlington cell with a cross-connected topology is reported. As a result, the linearity of mixer is increased effectively. In addition, the proposed circuit employs an active load and current bleeding technique to increase the conversion gain (CG) and reduce the noise of the circuit in the frequency of interest. The simulated third-order input intercept point (IIP3) is 12.5 dB while conversion gain is 14.5 dB. The proposed circuit provides a low noise figure of 4.55 dB at 2.4 GHz. Its power consumption is 17.4 mW with power supply of 1.8V.