Saelig Micsig SigOFIT series opto-isolated probes

19th May 2023

Harry Fowle

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Saelig has introduced the Micsig SigoFIT Series Opto-isolated Probes with amplitude/frequency characteristics and deliver a common mode rejection ratio (CMRR up to 112dB at 100MHz, over 100dB at 500MHz).

The full-range noise floor is 1.1mVrms max, and the 24-hour zero drift is less than 50uV. These SigOFIT probes feature Micsig's exclusive SigOFIT optical isolation technology, remotely powered by laser light or battery, offering extremely high isolation voltage to help engineers to see true, uncorrupted signals within their specified bandwidths.

Five bandwidth models are available for signals from 100Hz to 1GHz, with the measurement heads either battery-powered or opto-isolated LED laser-powered. The input test leads of the SigOFIT probes are short and have coaxial cables for transmission from the measurement heads. They present less than 3pF input capacitance load, which makes these probes ideal for testing SiC and GaN devices that can switch high voltages in a few nanoseconds and produce very high-energy high-frequency harmonics. Unlike traditional differential probes which can only test high-voltage signals, the SigOFIT series probes can be used with different attenuator tips to test differential mode signals from ±1V to ±2500V, achieving full-range output and high signal-to-noise ratio. Smaller in size than traditional differential probes, and with more precise probe tips, SigOFIT-isolated probes are easier and more versatile to use than conventional differential probes. With a fast response, signals can be tested immediately after power-on, with no need to wait for a warm-up period. Autozeroing in less than 1 second ensures accurate signal measurements in real-time. Even at the highest bandwidth, the SigOFIT probes still have approximately 100dB CMRR to perfectly suppress oscillations caused by high-frequency common-mode noise.