Influence of Interrupting Buried Layers and Ring-Loops on Electromagnetic Coupling in RFICs

Isolation degradations in BiCMOS RFICs resulting from low-resistivity buried layers and floating ring-loops have been investigated using the full-wave hybrid transverse waves formulation (TWF) method. To reduce such isolation degradations trenched-sinkers are introduced to interrupt the buried layers in order to increase impedance paths of noisy signals. The existence of "privileged directions" for the interruption of both buried layers and floating ring-loops has been demonstrated. The simulation results were in satisfactory agreement with measurements data, and with those obtained with commercial design tools