Isolation issues in multifunctional Si/SiGe ICs at 24 GHz

In this paper, the authors present the study of isolation issues appearing within circuits realized on 20 Ωcm silicon substrate and at high frequencies. Several aspects of substrate noise injection and reception have been analyzed. Experimental results, based on test structures, have been used to give an estimate of substrate coupling noise influence. Several techniques are described in order to improve the isolation within circuits. The isolation in a fully integrated, fully differential 24 GHz oscillator/16:1 divider block, which uses these methods, is presented.