Power Integrity

Created; 5/01/2020Last update: 5/09/2020


Power supply and its delivery path must met the load voltage ripple requirements in order for the product to operate reliably. Power integrity is an analysis on how well power supply deliver its power to  the load in terms of voltage ripple, Load voltage regulation and target current path impedance.


Measurement Analysis

Time Domain

Frequency Domain


Power Distribution Network (PDN)

Basic Power Supply Components


Bulk Capacitor

Decoupling Capacitor

Voltage Regulator

Remote Sensing

Design overview

Voltage Regulator power integrity design

Reduce output ripple

Reduce DC resistance

Load Power Integrity Design

Reduce input ripple

Measurement Technique 

Oscilloscope for time measurements

VNA for impedance vs frequency measure


Does capacitor packaging affect impedance vs frequency curve?

Yes! A larger capacitor with the same capacitance compared to a smaller package has higher parasitic inductance due to longer leads. high parasitic inductance has higher impedance at higher frequency, lowering the rise up frequency point,  resulting in width reduction of the bathtub curve. Hence the rule of thumb in design is use capacitor with smallest package with the same capacitance.

How do you lower DCR?

Summary & Conclusion

Power integrity ensures voltage ripple swing and power supply capability are met for the high speed digital electronics (complex load) to operate properly in all functional states.