Common-mode noise comparison study for lateral wire-bonded and vertically integrated power modules

This paper investigates the power module design for better common-mode (CM) noise performance. A high frequency full-bridge diode rectifier is studied as an example. For this circuit, a comprehensive parametric study and a proposed CM equivalent model are first presented to identify the most influential factors in CM noise generation and mitigation. It is shown that proper parasitic value and parasitics symmetry can improve the CM noise performance. A vertical module and a traditional wire-bonded lateral module are compared. The vertical module has smaller ac side CM parasitic capacitances, smaller ac side stray inductances and larger dc side CM parasitic capacitances, which are all favorable towards mitigating CM noise. Both modules are prototyped for verification, and their module parasitics are extracted using finite element method (FEM). A simulation case study shows that with the vertical diode module, over 30 dB CM noise reduction can be achieved below 10 MHz, under 7.4% unbalance between the ac side CM parasitic capacitances. Experimental results are presented to verify the simulation and analysis. It is also shown in thermal simulation that the vertical module exhibits at least 30% reduction on the thermal impedance.