Comparison of 24 GHz receiver front-ends using active and passive mixers in CMOS

This study compares the key parameters of two integrated receiver front-end architectures: low noise amplifier (LNA) with active mixer against LNA with passive mixer. The authors discuss the differences in the performance and their impact on system characteristics for radar applications. A low-IF down-conversion receiver implementation is considered. The results are compared in measurement for two 24 GHz receiver front-end chips realised in a 0.13 mum digital CMOS process. Both circuits have been characterised over automotive temperature range -40 to 125degC. The front-end with an active mixer offers lower LO power dependence and exhibits better temperature stability, whereas the front-end with a passive mixer has the advantage of better input-referred linearity and lower flicker noise.