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 electrical quantity (electromagnetic field or voltage), meaning the measured output represents the rate of change rather than the actual signal.

A passive integrator processes this derivative signal and performs analog integration, allowing engineers to reconstruct the real electromagnetic transient waveform.

They are commonly used in pulsed power systems, high-voltage testing, electromagnetic compatibility (EMC) experiments, and transient field measurements, where extremely fast events must be accurately captured and analyzed.

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 sensor’s output signal (proportional to dE/dt, dB/dt, or dV/dt) and reconstructs the corresponding electromagnetic or voltage waveform. This approach provides a stable and broadband response, which is particularly useful when measuring very fast transients.

Passive integrators offer several advantages compared with purely mathematical integration performed in software. Because the integration is carried out directly in hardware, the measurement system provides a real-time representation of the reconstructed waveform. This can simplify measurement setups and improve the stability and reliability of transient measurements, particularly for very fast pulses or high-bandwidth signals.

Passive integration also avoids potential issues related to numerical noise, sampling limitations, or post-processing errors that may occur with digital integration.

However, both methods can be complementary, and some measurement systems allow engineers to choose between hardware integration and software-based processing depending on their application.

A passive integrator is typically installed between a derivative sensor and the measurement instrument, such as a high-speed oscilloscope.

The sensor output is first connected to the integrator input, which is usually designed with 50-ohm impedance to ensure proper signal transmission. The integrator then outputs the reconstructed signal to the oscilloscope, often through a high-impedance connection.

For optimal measurement performance, the integrator should be used within a well-designed measurement chain, potentially including fiber optic links and shielded equipment to reduce electromagnetic interference during high-energy pulse measurements.

Montena passive integrators are designed for high-performance transient measurements in demanding electromagnetic environments.

Their compact design makes them easy to integrate into experimental setups, while their broadband response ensures accurate reconstruction of fast signals. These integrators are specifically optimized to work with Montena derivative sensors, providing a reliable measurement chain for high-speed electromagnetic phenomena.

Another advantage is their robust construction and simple operation, which help researchers and engineers obtain precise measurements with minimal setup complexity.

Combined with Montena’s sensors, fiber-optic links, and measurement software, they form a complete solution for capturing and analyzing fast electromagnetic transients.

Integrators can be tested by measuring their transfer function using a vector analyzer. Please note, however, that the transfer function of a passive integrator designed for a load impedance of 1 MΩ will exhibit limitations in the low-frequency range when measured with a 50-ohm vector analyzer.

A simpler method involves measuring the values of their internal components with a multimeter.

The user’s manuals for Montena Technology passive integrators provide detailed instructions.