Monolithic Broadband Gilbert Micromixer With an Integrated Marchand Balun Using Standard Silicon IC Process

A single-ended wideband downconversion Gilbert micromixer is demonstrated in this paper using 0.35-<formula formulatype="inline"><tex>$\mu$</tex></formula>m SiGe BiCMOS technology. A transimpedance amplifier with resistive feedback is utilized in the IF stage while a broadband Marchand balun is employed to generate wideband differential local oscillator signals. The planar Marchand balun topology employed in this paper can generate truly balanced signals even in the presence of the lossy low-resistivity (<formula formulatype="inline"> <tex>${\sim} {\hbox{10}}\ \Omega\cdot{\hbox{cm}}$</tex></formula>) silicon substrate. A systematic approach to measure the frequency response of each individual stage in a Gilbert mixer is developed in this paper. This single-ended wideband mixer has the conversion gain of 15 dB, <formula formulatype="inline"> <tex>${\rm IP}_{1{\rm{dB}}}$</tex></formula> of <formula formulatype="inline"> <tex>${-}$</tex></formula>19 dBm, <formula formulatype="inline"><tex>${\rm IIP}_{3}$</tex></formula> of <formula formulatype="inline"><tex>${-}$</tex> </formula>7 dBm, and the noise figure of 13 dB. The mixer works from 3.5 to 14.5 GHz.