Oscilloscope for Switching Power Supply Testing: Recommended Models and Setup

A purchasing guide for switching power-supply oscilloscope work, with recommended Keysight, Rohde & Schwarz, and SIGLENT models plus the probe chain required to use them safely.

Last updated: 2026-09-18

What this guide covers

A switching-power bench normally needs to see output ripple, startup, load-step response, gate timing, switch-node overshoot, and intermittent ringing. Buy the oscilloscope and probes as one measurement system. A grounded passive probe is not appropriate for a floating high-side node unless the complete circuit and probe connection make it safe.

Set the purchase requirements first

For an offline flyback, PFC, LLC, or DC-DC converter, document the highest bus voltage, switch frequency, fastest edge, number of simultaneous channels, longest capture window, and the smallest ripple you need to resolve. A practical four-channel bench typically needs a differential voltage probe, a current probe or shunt measurement, short ground accessories for low-voltage ripple, and enough memory to capture startup and the following steady-state event.

Recommended oscilloscope models

| Model | Useful published capability | Best fit |

| --- | --- | --- |

| Keysight InfiniiVision HD304MSO / HD3 series | Four analog channels, 14-bit ADC, 100 Mpts, up to 1.3 M waveforms/s; 200 MHz to 1 GHz configurations | Low-level ripple, control-loop work, and teams that value 14-bit vertical detail |

| Rohde & Schwarz MXO44 | Four channels; 200 MHz to 1.5 GHz options; 12-bit ADC, 400 Mpts standard memory, 2.5 Gsample/s on four channels | Fast fault capture, long startup sequences, and high channel-count power work |

| SIGLENT SDS5000X HD | Chinese brand; eight channels, 12-bit ADC, 350 MHz to 1 GHz options, up to 5 GSa/s and 2.5 Gpts/channel | Multi-rail converters, gate-drive plus current plus output captures, and high channel density |

These are direct recommendations, not a substitute for confirming availability, firmware options, probe compatibility, calibration status, and local safety requirements in the quote.

Probe package to put on the purchase order

Specify the differential probe by maximum differential voltage, common-mode rating, bandwidth, input capacitance, and CAT/derating conditions. Specify a current probe by DC accuracy, bandwidth, range, jaw or conductor geometry, and degauss procedure. For output ripple, specify a low-inductance tip-and-spring or coaxial method rather than a long flying ground lead. The supplier demonstration should reproduce one actual switching-node capture and one output-ripple capture with the proposed accessories.

Acceptance checks

1. Capture the planned load step with all required channels active.

2. Verify memory depth and sample rate at that channel count.

3. Repeat the switch-node measurement with the stated differential probe.

4. Save waveform, probe attenuation, bandwidth limit, time base, and trigger with the test record.