Power distribution system design methodology and capacitor selection for modern CMOS technology

Power systems for modern complementary metaloxide-semiconductor (CMOS) tech nology are becoming harder to design. One design methodology is to identify a target impedance to be met across a broad frequency range and specify co mponents to meet that impedance. The impedance versus frequency profiles of the power distribution system components including the voltage regulator m odule, bulk decoupling capacitors and high frequency ceramic capacitors are defined and reduced to simulation program with integrated circuit emphasis (SPICE) models. A sufficient number of capacitors are placed in parallel t o meet the target impedance. Ceramic capacitor equivalent series resistance (ESR) and ESL are extremely important parameters in determining how many c apacitors are required. SPICE models are then analyzed in the time domain t o find the response to load transients.