A wideband down conversion mixer with dual cross-coupled loops for software defined radio

The paper presents a proposed wideband down conversion mixer with dual cross-coupled loops for software defined radio applications. The proposed wideband mixer employs common-gate structure for wideband matching characteristic. Two cross-coupled loops are implemented within it. One is capacitively cross-coupled and the other is directly cross-coupled. The first loop is to enhance the effective transconductance of amplifier stage while the second one is to provide the negative transconductance for the switching stage. Both of them work for gain enhancement without any penalty of power dissipation. To validate the proposed wideband mixer, a wideband mixer has been designed through TSMC 0.18-μm RF CMOS. Simulated results show that it has 16.8 dB voltage gain, 3dB bandwidth range from 2 GHz to 5 GHz, minimum 6 dB NF and -10.4dBm IIP3 with 1.2 mA current consumption from 1.8 V voltage supply.