Low-voltage differential probe recommendations——Product comparison between PMK and Tektronix

In test and measurement, various test probes are often used, and probes fall into many types to meet various test environments. How to choose a suitable probe

has become a troubling issue for engineers,This article compares low-voltage differential probes from two brands to provide selection recommendations.

First, what is a differential probe? In some specific tests, floating measurements are required, and the probes used for isolated measurement to handle this measurement environment

are differential probes,Differential probes are divided into low-voltage differential probes and high-voltage differential probes.

Low-voltage differential probes are mainly used to measure low-voltage differential signals. Low-voltage differential signals are common in high-speed digital circuits, generally with bandwidth above 1GHz,

and the voltage is relatively small, with a common amplitude of ±8V;High-voltage differential probes, however, target high-voltage differential signal measurements with voltages as high as the kV range; such signals are

common in switching power supply measurements. Differential signals are referenced to each other, not to groundas the reference point. Ordinary single-ended probes can also

measure differential signals, but the obtained signal differs greatly from the actual signal, and the “ground bounce” phenomenon may occur.Differential probes can measure not only differential signals

but also single-ended signals. Moreover, when measuring single-ended signals, differential probes have the following advantages: higher input impedance, reducing thecircuit under test's

loading effect; effectively suppressing common-mode noise and improving the signal-to-noise ratio of the signal; avoiding ground loops or ground conflicts and preventing interference with measurement results;

allowing flexible selection of test points,without being limited by oscilloscope grounding.

This article mainly provides selection recommendations for low-voltage differential probes; low-voltage differential probes have many applications in measurement, such asCommon high-speed serial bus

design, verification, debugging, and validation;signal integrity, jitter, and timing analysis; manufacturing engineering and test; disk drive read channel designetc.

The main brands recommended in this article are Tektronix (US) and PMK (Germany); both are relatively strong brands in the industry.

Tektronix's low-voltage differential probes include the TDP series and the P6000 series.

The specifications of Tektronix TDP series low-voltage differential probes are as follows:

The probe specifications of the P6000 series are as follows:

The specifications of PMK HSDP series probes are as follows:

After comparing the specifications of the two, it was found that each has advantages and disadvantages, so a comparison table was made based on their specifications, as follows:

From this comparison chart, we find that PMK's maximum input voltage and bandwidth are superior, and the common-mode rejection ratio specifications are clearer,

but the common-mode rejection ratio of the HSDP series at 1 MHzlags somewhat behind that of Tektronix's low-voltage differential probes.

Overall, the PMK HSDP series is superior in performance to Tektronix's TDP low-voltage differential series.

The common-mode rejection of Tektronix P6000 series low-voltage differential probes at 1x attenuation ratio is about 10% higher than that of the HSDP series, but at 10x attenuation

the common-mode rejection ratio is about 10% lower.PMK's HSDP2050 has higher bandwidth, and its maximum input voltage is also much higher than Tektronix's, but the HSDP series

does not have specific DC accuracy specifications, only noise specifications.The HSDP series bandwidth starts at a minimum of 1.8 GHz and reaches a maximum of 4 GHz;

Tektronix low-voltage differential probe products have a bandwidth range from 400 MHz to 3.5 GHz; Tektronix low-voltage differential probes offer a wider selection of bandwidths.

The Tektronix P6000 series also offers two attenuation ratios, whereas the HSDP does not offer multiple attenuation ratios.

At the same level, the HSDP series offers wider bandwidth and a wider voltage measurement range,Its input resistance is higher and its input capacitance is smaller.

In summary, the two brands each have advantages and disadvantages, but Tektronix low-voltage differential probes require a Tektronix oscilloscope with a TekVPI interface for power,

This creates compatibility issues with oscilloscopes from other brands,whereas the HSDP does not have this problem, but it requires a matching power supply; its compatibility is better.

If other questions arise during selection, you can contact us directly for technical consultation.