The SQG15-DC is a 10:1 passive low impedance probe with DC coupling, measuring from 0 Hz to above 1.5 GHz. Through its BNC connector it works with any instrument that has a 50 Ω input, or with a high impedance input through a 50 Ω feed-through termination, and it reaches high-speed digital and RF test points on the PCB without soldered wires.
With no DC block in the signal path, the probe shows the true DC level together with the edges, so offsets and baseline shifts stay visible. The response is flat within ±0.5 dB from DC to 1.5 GHz, so slow and fast parts of the same signal are shown on the same amplitude scale.
Typical measurements include logic levels and threshold margins on high-speed digital lines, pulse amplitude, overshoot and settling on clocks and data lines up to 3 Gbps, supply rails where ripple and DC level are seen together, and RF signals on 50 Ω lines and RF front-ends where the DC operating point is part of the measurement. Besides oscilloscopes, the probe works with sampling oscilloscopes, network analyzers, spectrum and modulation analyzers, receivers, power meters and millivoltmeters with a 50 Ω input.
At DC the 500 Ω tip impedance also acts as a load, so the probe draws a small current from the node it touches. It is best used on low impedance points such as 50 Ω lines, terminated outputs and supply rails, while a biased high impedance node is better measured with the SQG15-AC. The typical tip capacitance is 0.35 pF, the return loss for the probed line is typically -26 dB to -11.5 dB up to 1.5 GHz and the transition time is below 190 ps.
The probe comes 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 lines up with board-mounted RF connectors and tight signal and ground pairs. The ground spring covers ground points 6.5 mm (0.26 in) away, and on the SQG15 both options keep the full 1.5 GHz bandwidth. A spare spring-loaded test needle is included, so a worn needle can be swapped on the spot.
Each SQG15-DC has its own serial number (SPID), and the S-parameters measured on that individual 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 complete probe with its 1.2 m (47 in) cable weighs 34 g (1.2 oz), and the low center of gravity holds it still in a PCBite holder during long captures. It works handheld as well and is delivered in a storage case with the probe holder, 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 16.4 V RMS at the probe tip.
