Isolated Oscilloscopes: Why They Are Critical for Power Electronics Measurement

Brown keys

At Embedded World 2026, one particular measurement setup stood out—not because of extreme bandwidth or flashy specifications, but because of a fundamentally different architecture.

It was built around a simple but powerful idea:

Isolation.

This concept is not new, but its implementation in modern oscilloscopes is evolving in a way that directly responds to the challenges of power electronics systems.

The Limitation of Traditional Oscilloscopes

Conventional oscilloscopes are designed with a shared ground architecture.

All input channels are referenced to the same electrical ground, which works well for low-voltage and ground-referenced measurements.

However, in modern applications such as:

  • Motor drives
  • High-voltage DC systems
  • Inverters and switching power supplies

this assumption breaks down.

Engineers are no longer measuring signals in a unified ground domain, but in floating, high-energy environments.

This creates several critical risks:

  • Ground loops
  • Measurement distortion
  • Probe damage
  • Potential short circuits

 

A Different Measurement Architecture

The system observed uses a fundamentally different approach:

Each channel is electrically isolated.

This is not just isolation at the front-end—it is architectural.

Each channel includes:

  • A dedicated ADC
  • An independent ground reference
  • Electrical isolation from all other channels

More importantly, the signal is digitized close to the measurement point.

The signal path becomes:

→ Probe
→ Local ADC (remote digitizer)
→ Optical fiber transmission
→ Main processing unit

 

Why Optical Isolation Matters

The use of optical fiber is not just a design choice—it is essential.

1. Complete Electrical Isolation

Optical transmission eliminates any conductive path between the measurement point and the instrument.

This enables safe measurement in high-voltage systems.

 

2. Immunity to Electromagnetic Interference

Power electronics environments are dominated by:

  • High dv/dt switching
  • Strong EMI
  • Fast transient events

Copper-based transmission is highly susceptible to these effects.

Optical links are not.

 

3. High Common-Mode Capability

In systems like:

  • Three-phase motor drives
  • SiC / GaN switching circuits

common-mode voltages can be extremely high.

Traditional oscilloscopes struggle in these conditions.

Isolated architectures are specifically designed for this.

 

A Shift in Measurement Philosophy

This type of oscilloscope does not compete in the traditional GHz bandwidth race.

Instead, it prioritizes:

  • Measurement integrity
  • High resolution (e.g., 14-bit)
  • Multi-channel accuracy

This reflects a broader industry shift:

From:

→ “How fast can we measure?”

To:

→ “How accurately can we measure in real conditions?”

 

Key Applications

This architecture is particularly relevant for:

  • Motor control systems (FOC, three-phase analysis)
  • Double pulse testing (IGBT, SiC, GaN)
  • Power conversion systems (DC-DC, inverters, UPS)
  • Energy storage and EV platforms

 

Industry Perspective

What may appear as a niche solution is actually a response to a structural change in the industry.

Driven by:

  • Electrification
  • Renewable energy systems
  • High-efficiency power devices

measurement requirements are evolving rapidly.

Oscilloscope design is following.

 

Conclusion

Oscilloscopes are no longer defined only by bandwidth.

In high-voltage, multi-domain systems, isolation is becoming the foundation of reliable measurement.

This is not just an incremental improvement.

It is a shift in how engineers interact with real-world signals.

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