Impedance balance control for suppression of fluctuation on ground voltage in LSI package

Simultaneous switching current of a CMOS circuit causes power and ground bounces. The voltage fluctuation is injected into the CMOS substrate, and it degrades the performance of the circuit operation. In this report, we focus on the fact that parasitic couplings in the CMOS substrate and parasitic inductance in the power and ground connection form a bridge circuit, and we demonstrate that the voltage bounce can be suppressed by controlling variable resistances that are inserted between the substrate resistive coupling and the conductor line for the DC supply. The effectiveness of this method is verified with a scaled quad flat package (QFP) and we reduced the measured voltage bounce about 40 dBμV.