Distributed matched bypassing for board-level power distribution networks

Power-distribution networks need to provide impedance response with specified shape/value over a wide frequency band. Bypass capacitors with different values, and capacitors and planes may create resonance peaks, unless the capacitor parameters are selected properly. Distributed matched bypassing (DMB) is suggested to create a smooth impedance profile. DMB requires components with Q/spl Lt/1, which in turn requires user-defined ESR. Different options are shown to set (increase) the ESR of bypass capacitors. The concepts of bypass quality factor (BQF) and bypass resistor (BR) are introduced.