Today’s technologies continue to reach higher frequencies and wider bandwidths. Take, for instance, 5G in the U.S.—it will utilize 28- and 39-GHz frequency bands with 1.2 GHz of bandwidth. The IEEE 802.11ay standard makes use of frequencies between 60 and 70 GHz with 2-GHz bandwidths. Satellite-communication (satcom) systems routinely extend beyond 70 GHz with bandwidths greater than 5 GHz. The list of these emerging high-frequency and high-bandwidth technologies grows every year.
While it’s exciting to think about the possibilities surrounding millimeter-wave (mmWave) frequencies and above, advances such as these stress the overall capabilities of today’s test-and-measurement equipment. To truly show that the technology is working, one must measure it. Test-and-measurement instrument classes such as spectrum analyzers have limitations above 50 GHz, which necessitates finding another option to test at these high frequencies.
One class of instrument that’s gaining traction is the real-time oscilloscope. While rarely considered in the past, real-time oscilloscopes continue to make major strides in terms of both bandwidth and signal integrity performance, and thus could be an excellent choice for emerging markets among RF instruments.
The Easy Specification to Consider: Bandwidth
The first and most important specification centers around having the bandwidth to make measurements at very high frequencies (i.e., above 50 GHz). As recently as 2010, oscilloscope bandwidths were limited to just 30 GHz. Of course, that bandwidth spans dc to 30 GHz, so even as early as 2010 one could measure very wide bands with an oscilloscope. Unfortunately, reaching frequencies greater than 30 GHz required a downconverter. Extra calibration was also needed to remove loss and maintain a flat magnitude.