PASSIVE INTEGRATORS

Passive integrators are electronic devices designed to recover the original waveform measured by derivative sensors such as B-dot, D-dot, or V-dot probes. These sensors produce signals proportional to the time derivative of the measured quantity. A passive integrator performs analog integration, allowing engineers to reconstruct the real electromagnetic transient waveform.

A passive integrator converts a derivative signal into the original physical quantity by performing an analog integration of the input signal. When connected to a derivative sensor, it processes the output (proportional to dE/dt, dB/dt, or dV/dt) and reconstructs the corresponding waveform. This provides a stable and broadband response, particularly useful for very fast transients.

Passive integrators perform integration directly in hardware, providing a real-time representation of the reconstructed waveform. This simplifies measurement setups and improves stability for very fast pulses or high-bandwidth signals. Passive integration also avoids numerical noise, sampling limitations, or post-processing errors that may occur with digital integration.

A passive integrator is installed between a derivative sensor and the measurement instrument, typically a high-speed oscilloscope. The sensor output connects to the integrator input (usually 50-ohm impedance); the integrator outputs the reconstructed signal to the oscilloscope, often through a high-impedance connection.

Montena passive integrators feature compact design for easy integration into experimental setups, broadband response for accurate reconstruction of fast signals, and specific optimisation to work with Montena derivative sensors. Combined with Montena’s sensors, fibre-optic links, and measurement software, they form a complete solution for capturing and analysing fast electromagnetic transients.

Integrators can be tested by measuring their transfer function using a vector analyser. Note that the transfer function of a passive integrator designed for a 1 MΩ load impedance will show limitations in the low-frequency range when measured with a 50-ohm vector analyser. A simpler method: measure the values of internal components with a multimeter. Detailed instructions are in the user’s manuals.