DCDC power ripple test

1、 Oscilloscope probe

1.1、 Probe selection

priority （ From high to low ）	advantage	Inferiority
Power ripple probe	Minimize the noise of measuring tools , At the same time, it can also provide more bandwidth , In order to view more signal contents .	Expensive
Coaxial cable
1:1 Passive probe plus ground ring
10:1 Passive probe plus ground ring		As the signal passes through the attenuation of the probe , In order to restore the size of the real signal , The signal will be further amplified inside the oscilloscope , At this time, the background noise of the probe and the local noise of the oscilloscope will be amplified , The magnification is the reciprocal of the attenuation ratio . So the greater the attenuation factor , The more the background noise of the measurement system is amplified .

1.2、 Earth ring （ must ）

correct （√）	error （×）

1.3、 Why not choose an active probe ？

2、 Oscilloscope setting

Coupling mode	AC coupling , No concern DC component
Input impedance	50Ω（ The probe is coaxial cable ）
Bandwidth limitation	20MHz, Remove unnecessary noise effects
Sampling time	Manually adjust until the ripple shape is clearly seen
DC offset	0
Sampling methods	Real time sampling , Cumulative 300 A little bit

Reference material

Measure the power ripple with an oscilloscope , Have you really measured it ？