Small Signal Analysis with Oscilloscope Current Probes
應用說明
Probing considerations
If you are measuring the small amplitude of ripple and noise on your power rail or devices, you may need to use an oscilloscope at or near its more sensitive V/div setting. First, try using a probe with a lower attenuation ratio such as 1:1 probe, rather than using the standard passive probe with 10:1 attenuation ratio that shipped with your instrument. With a 10:1 probe, not only is the oscilloscope’s base-line noise floor increased by a factor of 10, but the minimum V/div setting of scope is also ten times higher than with a 1:1 probe.
Another very important tip in probing small signal is to minimize the amount of residual noise picked up by the probe. A 15-cm long ground lead and a hook tip that typically come standard with a general purpose passive probe could pick up noise generated by the target signal or other devices nearby. Use a smaller probe tip and a shorter ground connection such as a BNC adapter on the board or a bayonet type of ground lead reducing noise picked up by minimizing the loop of the connections and also reducing inductive loading.