Overview of some options to create low-Q controlled-ESR bypass capacitors

Abstract

Low-Q bypass capacitors with controlled ESR offer the advantage of creating resonance-free power distribution networks (PDN) with low sensitivity to component tolerances, and achieving a predictable impedance profile with the minimum number of components. Low Q bypass capacitors, termed bypass resistors, can be created either by reducing the inductance of the part, and/or by raising the equivalent series resistance (ESR). In multi-layer capacitors, ESR can be raised by using resistive plates, and/or resistive terminations, or by adding resistance externally with low inductance. Low-resistance capacitor plates can be patterned outside the high-frequency current loop. In thin-film capacitors, ESR can also be raised by reducing the thickness of capacitor plates.