Keysight’s UXR1104A Infiniium UXR-Series Oscilloscope captures the record for bandwidth in a real-time sampling oscilloscope at 110 GHz. Now in second place, Teledyne LeCroy’s LabMaster 10 Zi-A reaches 100 GHz while the Tektronix DPO70000SX ATI slips to third place at 70 GHz.
At 110 GHz, Keysight’s UXR1104A Infiniium UXR-Series Oscilloscope is the current bandwidth record-holder for real-time oscilloscopes.
The Keysight announcement comes as little surprise given that the company announced the analog front-end technology in 2016. Until this announcement, Keysight was in third place at 63 GHz.
Keysight and Teledyne LeCroy take different approaches to the bandwidth issue. Teledyne LeCroy uses a technique called digital bandwidth interleaving (DBI). For 100 GHz, this technique divides the incoming signal into three 36-GHz frequency bands. Using RF techniques, the oscilloscope frequency-shifts the middle and upper bands to baseband, then samples all three bands and reassembles them to recreate the original time-domain signal. The analog and sampling hardware need only go to 36 GHz. Can the company add a fourth frequency band? If so, it could jump back into the lead in a big way. Is 150 GHz possible with DBI?
Keysight takes a more traditional approach. Using an analog front end that includes a Faraday cage, the oscilloscope samples at full bandwidth. Even at that, the UXR series boasts 10-bit analog-to-digital converters (ADCs) as opposed to the eight bits of the competitors. It can also measure at full bandwidth while running all four channels. Teledyne LeCroy’s entry can give you just one channel at 100 GHz (four channels at 36 GHz). Tek’s DPS77002SX also provides one channel at 70 GHz, though it’s a two-channel instrument.
Keysight’s 110-GHz real-time oscilloscope uses a Faraday cage over sensitive analog circuits to reduce noise.
Who needs this bandwidth, anyway?
If you're sitting at your bench designing an audio or electromechanical device, you may wonder who would spend hundreds of thousands of dollars for the high bandwidth? The most common use for these top-of-the line instruments is serial data streams. Today, we’re seeing 112-Gbps (56-Gbaud) data streams using PAM4 — four-level pulse-amplitude modulation — being demonstrated. That’s 56 Gbaud. So, 110 GHz doesn’t even cover the second harmonic. Currently, 56 Gbps running PAM4 (28 Gbaud) and 56-Gbps non-return-to-zero (NRZ) signals are running over fiber and copper. 400-Gbps Ethernet uses 8×56-Gbps lanes.
NRZ signals have two levels, producing a single-eye diagram, while PAM4 has four levels and three eyes. PAM4 produces the same data rates at NRZ at half the bandwidth. But the eyes are one-third the height, making them harder to detect.
Speaking of oscilloscopes, nobody loved them more than former EDN technical editor Dan Strassberg, who passed away last week. Dan would have loved Keysight’s announcement but would have questioned the technology as he always did.