The HVFO is an affordable, optimally designed probe for measurement of small signals floating on an HV bus in power electronics designs or for EMC, EFT, ESD, and RF immunity testing sensor monitoring. It far surpasses the measurement capabilities and signal fidelity of both conventional HV differential probes and acquisition systems that rely on galvanic high voltage isolation. Furthermore, it mitigates the need to rely on dangerous test setups that require floating the oscilloscope and probe.

Key Features

• 60 MHz bandwidth
• Common-mode (safety) voltage virtually unlimited (optical isolation)
• Superior Noise and Rejection
  • 140 dB CMRR
  • Low loop inductance
  • Low attenuation
• Reduced DUT loading, better pulse response compared to conventional HV differential probes
• Selectable tips for from +/-1V to +/-40V
• Eliminates need to "float" the oscilloscope
• ProBus-compatible with many Teledyne LeCroy oscilloscopes

Upper-side gate drive signals will be faithfully reproduced without loading and distortion or mysterious ringing, overshoots and transients, providing a clear view of the Miller effect on the gate drive signal. Any conventional HV differential probe with high tip capacitance in parallel with C_GE or C_GS, and/or high impedance and large loop inductance in series with the gate drive impedance will at best load the gate drive signal or pick up interference and at worst cause circuit malfunction. The HVFO performs much better for these measurements.

The HVFO measures only the low voltage sensor voltage across its high impedance input leads. Total load on the device under test (DUT) is very small. Furthermore, the low lead loop inductance, >100dB CMRR, and low attenuation provide superior signal fidelity, noise and rejection.

AC and DC sensor signals floating at a high voltage or in the presence of EMC disturbance signals can be acquired with high signal fidelity and correctly correlated to in-circuit and control activities.

Optical isolation between the probe tip and the oscilloscope input reduces adverse loading of the DUT, provides faithful pulse response, and increases confidence in the measurement. Safety against dangerous high voltage levels can be ensured and unsafe "floating" of the oscilloscope can be avoided.

High CMRR (>100 dB) provides more accurate representation of the measured signal despite the presence of high dV/dt or dA/dt events elsewhere in the circuit. The test lead is optimized to limit loop inductance and radiated pickup. Tip attenuations are optimized for a wide range of signal amplitudes.

The HVFO103 is small enough to fit in tight spaces, provides just enough performance for real-world needs, and is affordable enough to fit the tightest of equipment budgets. A single laser and fiber optic cable is used for optical isolation and modulated signal + data communication, and multiple tips achieve different operating voltage ranges.