The J2111B current injector is possibly the most versatile of the Picotest Signal Injectors for power integrity and power electronics testing applications.
This current injector can be used for:
3-port impedance testing in the frequency domain
Stability analysis via output impedance and Non-Invasive Stability Measurement (NISM)
Transient time domain load step testing
This injector is not designed to replace an electronic load; however, it is capable of performing a small signal step loading at switching speeds and bandwidths that electronic loads cannot achieve, such as 40 MHz or 20ns Rise/Fall times.
The capacitance of an electronic load, which is generally too high and impacts the measurement, is not an issue for the current injector. Incorporating a 40MHz current monitor, the current injector can also be used to measure output impedance, as well as the stability of a three-terminal regulator or a filter combined with the negative resistance of a switching converter or power supply.
The key benefit is that step, stability, and impedance measurements can all be made non-invasively while connected to hardware already integrated into its production form.
For example, the control loop for a fixed output LDO cannot be broken, and its stability is directly measured since the loop is within the IC. Load step testing is currently the only way to check stability besides simulation. Such testing does produce an exact phase margin result. While the J2111B current injector can perform the load step testing, it can also record the output impedance, and from that, an exact phase margin result can be computed.
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