The Non-invasive Stability Measurement (‘NISM') software brings the unique stability measurement capability to the Keysight E5061B vector network analyzer. The software add-on, available now for new or existing customers, allows the instrument to perform stability margin measurement of op amps, voltage references, voltage regulators, LDOs, switching amplifiers, POLs, input filters and all types of power converters through their output impedance.
NISM is an alternative to a Bode plot measurement that allows the user to assess circuit or filter stability even when the control loop is not accessible. It determines phase margin from an output impedance measurement. The software guides the user through a few simple steps to obtain the stability margin from a circuit's output impedance. The measurement results can be saved or printed as with other E5061B measurements.
E5061B users can use one, two, and three port impedance measurements (1-port reflection, 2-port shunt thru, 2-port series thru,3-port voltage/current, etc.). The software supports the gain-phase frequency and high frequency S parameter ports to assess the stability of all types of the aforementioned circuits ranging from mohms to kohms and up to the full frequency range of the VNA.
Testing Stability Where No One Has Gone BeforeVery often you cannot make a Bode plot for a number of reasons. For example, the stability of linear or switching regulators, whose control loops are not exposed externally from the IC, cannot be assessed using a traditional Bode plot test. In those cases, the non-invasive stability margin measurement is the only way to verify stability for these types of circuits. Whether traditional loop breakage is not possible or not, NISM can perform the stability assessment and now the Keysight E5061B has the capability.
