Abstract
A miniaturized multi-layer symmetrical stacked balun designed and fabricated in a commercial CMOS technology are presented. The measured performance of the compensated single-ended drive balun, in good agreement with simulation, covers the frequency range of 800MHz~2.5GHz with the amplitude mismatching less than 0.4dB and phase errs less than 3.2 degrees. The die size of the balun is only 270µmX270µm.