Flexible Noninvasive Broadband Voltage Probe as an Anti-Interference Monitoring Tool

Noninvasive measurement methods are gradually gaining attention as a monitoring tool for time-domain signals. In this paper, a novel non-invasive flexible voltage probe with an operating frequency of 1MHz to 1GHz is proposed for monitoring the voltage signals at the input and output ports of a low noise amplifier (LNA) module. The flexible probe design and its performance are verified through simulation and experiments. The probe can be pasted to the trace surface for non-invasive voltage measurement. The probe has been verified to operate properly in a strong electromagnetic environment of 24.3 kV/m. The transmission coefficients obtained at different lengths, bending angles, bending times, and long-term bending show high consistency, with an average error of less than 5%. In addition, the reconstructed voltage time-domain curves closely match the directly measured voltages under an injected double-exponential voltage waveform, with an average error of 2.44%. In the application test, the input and output signals coupled by the probe are calculated by the time-domain reconstruction method. It is highly consistent with the theoretical gain value of the LNA. The experimental results show that the flexible probe can be used as a non-invasive time-varying voltage monitoring tool at the port of the LNA module.