Affordable 150 MHz Differential Probe in Development That Works on Any Oscilloscope

Differential probes enable oscilloscopes to measure differential signals or non-ground referenced measurements like the switching loss of a power converter's MOSFET. Usually, these probes are specific to one manufacturer's oscilloscope, designed for high-voltage operation, or expensive. Craig of Milky Way Systems aims to make differential measurements accessible to anyone with a 150 MHz differential probe named PD150.

The PD150's design is slim and compact. At one end is a 2.54-millimeter header for the differential input, and at the other is a USB-C for power and an SMA connector providing signal output.

Most oscilloscope vendors offer a variety of differential probes, but they tend to only connect to their proprietary power and controller ports. And third-party differential probes options usually focus on niche measurements like high-voltage or very low bandwidth. Both tend to have a very high cost associated with them. (e.g., Thousands of dollars per probe.)

PD150's mechanical size and electrical specifications make it a general-purpose probe. Milk Way Systems says the target is for the probe to cost less than $300 USD.

Its key electrical specifications are:

The PD150 testing page details how some specifications were tested and how the probe performed.

Several features improve the probe's usability. For example, DC offset adjustment is automated, and there is a semi-automated adjustment for low-frequency common-mode rejection ratio (CMRR). Additionally, a multi-color LED lets you match the color to the oscilloscope channel to make identification easier.

This probe works with almost any oscilloscope. The probe's output terminates into 50 ohms. So, your oscilloscope needs a 50 ohm termination. Look at the front panel of your oscilloscope to determine if it supports 50 ohm inputs. There will be a max voltage rating specific to 50 ohms. On other oscilloscopes with only a 1 megaohm input, you can use a 50-ohm termination adapter.

Milk Way Systems is still in the prototype stage with the PD150. They expect shipments to happen in 2024. While you cannot pre-order one today, you can join the mailing list on the PD150 product page to know when more news is available.