The SQG30-DC is a 10:1 passive low impedance probe with DC coupling that measures from 0 Hz to above 3 GHz. The SMA output connects to oscilloscopes and other instruments with a 50 Ω input, and the probe picks up fast digital and RF signals directly on the PCB without soldered wires.
Because nothing blocks DC in the signal path, the DC level, the edges and the high-frequency content appear in the same capture. The response is flat within ±0.5 dB from DC to 2.7 GHz, so a slow drift and a fast transition on the same line are measured on one amplitude scale.
Typical measurements include logic levels, overshoot and settling on clocks and fast data lines up to 6 Gbps at the fundamental, signals at terminated 50 Ω outputs and test points, and supply rails where ripple and transients are seen together with the DC level. On the RF side it covers front-ends below 3 GHz, including the 2.4 GHz band used by Wi-Fi and Bluetooth, with the bias point visible in the same trace. Besides oscilloscopes, the probe works with sampling oscilloscopes, network analyzers, spectrum and modulation analyzers, receivers, power meters and millivoltmeters with a 50 Ω input.
The 500 Ω tip impedance applies at DC as well, so the probe draws a small current from the node it touches. It is best suited to low impedance points such as 50 Ω lines, terminated outputs and supply rails, while a biased high impedance node is better measured with the SQG30-AC. The typical tip capacitance is 0.35 pF, the return loss for the probed line is typically -26 dB to -4.3 dB up to 3 GHz, the transition time is below 103 ps and ringing stays within 0.125 dB at 3 GHz.
The probe ships with dual spring-loaded ground needles and a ground spring. The two ground needles sit 2.3 mm (0.09 in) on each side of the signal needle, 4.6 mm (0.18 in) apart, which fits board-mounted RF connectors and tight signal and ground pairs and keeps the full 3 GHz bandwidth. The ground spring covers ground points 6.5 mm (0.26 in) away with the bandwidth limited to 2 GHz. A spare spring-loaded test needle is included for when the first one wears.
Every SQG30-DC is marked with its own serial number (SPID), and the S-parameters measured on that specific probe can be downloaded for simulation or de-embedding. The insulated head measures 90 mm (3.5 in) by 8.9 mm (0.35 in), the probe weighs 34 g (1.2 oz) including the 1.2 m (47 in) cable, and the low center of gravity keeps it still in a PCBite holder during long captures. It can also be used handheld, and it comes in a storage case with the probe holder, an SMA wrench, color coded cable holders and a tip protection cap.
The probe is rated CAT 0 under IEC 61010-031:2022 for circuits not directly connected to mains, with a maximum continuous input of 15.2 V RMS at the probe tip.
