  As ASIC supply voltages approach one volt, the source-impedance goals for
power distribution networks are driven ever lower as well. One approach to
achieving these goals is to add decoupling capacitors of various values until
the desired impedance profile is obtained. An unintended consequence of this
approach can be reduced power supply stability and even oscillation. In this
paper, we present a case study of a system design which encountered these
problems and we describe how these problems were resolved. Time-domain and
frequency-domain analysis techniques are discussed and measured data is
presented.
