Questions on J2111A and J2130A
Hello,
I have two additional questions.
I understand that the J2111A Current Injector applies a small AC current to the output of a device when using the Voltage / Current measurement. The intent is to make a small signal measurement. What guidance is there when the load of the converter is well less than a 1A? Should I define "small signal perturbation" as "10% of the DC load"? If this is correct, then should I inject my own signal at 10mA/V when I have a DC load less than 250mA to maintain a small signal measurement?
When using a DC block to isolate the DUT from the 50 ohm termination inside the Bode 100, it has been mentioned to watch out for inrush into the Bode 100 to prevent damage to the device. Is there any guidance on this, such as limiting the turn on ramp rate of the converter (such as perhaps 1V/ms)?
Thanks!
Small signal is really defined by the limits of the instrument. While your 10% is reasonable, you could probably use much smaller signals than that. The J2112A is much harder to keep stable, but has a larger current.
The input voltage to the instrument depends on the instrument and they are not often well documented. I did just have a $6,000 repair on one of my scopes due to damaging the front end. The Bode 100 is pretty robust, but not all instruments are. A simple trick is to power up with the scope in High Z. The DC block will charge through the scope 1MOhm input impedance. After a few seconds it will be fully charged and you can safely switch to 50 Ohms.