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Products > NISM Software
NEW Non-Invasive Measurement Information
NISM (Non-invasive Stability Measurement) Software
  • Easy-to-Use - Convert Output Impedance to Phase Margin
  • Add stability testing to the Keysight E5061B vector network analyzer
  • Filters, Opamp, Regulators (Linear and Switching), POLs, Amplifiers, References
  • Works with 1, 2 and 3 Port measurements (high and low frequency ports)
  • Print and Save Results
  • Works even when you can’t break the control loop
  • Works In-Circuit
  • Within 1 degree of Bode Plot Results (from 1 to 65 degrees).
  • Measure what Bode Plots can't

If the video does not appear below, click here to watch the Measuring Stability Margin with the E5061B VNA Video presented by Picotest.



  • Product Information
  • Application Notes
Model Description Price  
E5061B NISM NISM Software for the Keysight E5061B (SINGLE USER License*)
E5061B NISM/PB01 NISM Software for the Keysight E5061B with 1 Port Probe (SINGLE USER License*)
E5061B NISM/PB02 NISM Software for the Keysight E5061B with Probe Bundle (SINGLE USER License*)

Model Description Price  
E5071C NISM NISM Software for the Keysight E5071C (SINGLE USER License*)
E5071C NISM/PB01 NISM Software for the Keysight E5071C with 1 Port Probe (SINGLE USER License*)
E5071C NISM/PB02 NISM Software for the Keysight E5071C with Probe Bundle (SINGLE USER License*)

*Please inquire for the cost of multi-instrument or corporate licenses.

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 Before
Very 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.

Picotest PDN Probes Eases Output Impedance Testing
In many instances, the power converter’s output capacitor is very small and the stress of soldering a cable might lift the capacitor from the PCB, assuming there is even sufficient physical access for the cable. In the case of an opamp, test connections can alter the measurement. Fortunately, now there is a better way to gather impedance data.  Picotest’s 1-port and 2-port PDN handheld probes allow easy access to the output test point and maintain a true 50Ω transmission line characteristic from the VNA to the part being measured (i.e. no loading of the measurement).  The 1-port probe can be used to measure the impedance using the 1-port reflection method and the 2-port probe can be used to measure the impedance using the 2-port shunt or series thru method. Once the impedance is measured, the NISM software provides the associated phase margin.