A 9-21 GHz miniature monolithic image reject mixer in 0.18-μm CMOS technology

A compact 9-21 GHz monolithic image reject mixer (IRM) with a chip dimension of 0.9 × 0.74 mm² has been designed and fabricated using a standard 0.18 μm CMOS technology. The compact configuration is composed of a 90° coupler for local oscillator (LO) and two doubly balanced ring mixers for mixing core. Particularly, a radio frequency (RF) dual balun with advanced intermediate frequency (IF) extraction technique can not only eliminate the use of power divider in IRM design, and simultaneously provide balanced signals for ring mixing, but also obtain high side band suppression without any additional IF low-pass filter. Moreover, the entire passive circuits are constructed by utilizing broad side coupling structure to achieve high-level integration further. From the measured results, the IRM exhibits a 19.4-22.4 dB conversion loss, a maximum image rejection ratio (IRR) of 34 dB, all port-to-port isolations better than 28 dB over RF frequency range of 9 to 21 GHz, and an input 1 dB compression power of 14 dBm.