Dampening high frequency noise in high performance microprocessor packaging

Abstract

In high performance microprocessors, power supply noise needs to be controlled to ensure reliable high speed bus operation. This is generally done with high quality package capacitors and on die capacitance. These capacitors are generally lower equivalent series inductance (ESL) and lower equivalent series resistor (ESR). Because the ESL is not zero, die capacitance is required to reduce the impact of this ESL on the power supply noise. Alternatively, in this paper, we present a novel approach of using an on-die metal resistor in series with the package capacitance to dampen the high frequency noise. We show by validation on the 90 nm technology that this technique is capable of reducing the noise by nearly 80% without adversely affecting the bus speed.