Low-Noise Measurements with QuietChannel Technology on the 7 Series Oscilloscope

If you've ever measured high-speed signals in real-world channels, you know how challenging it can be. Lossy cables, fixtures, and connectors blur the signal before it even reaches the oscilloscope. That's why engineers resort to de-embedding—a mathematical process that removes channel effects so the signal can be observed as if it were coming directly from the transmitter.

However, there's a catch: while de-embedding restores lost high-frequency components, it also increases oscilloscope noise. It's like sharpening a blurry photograph—you restore detail, but graininess and artifacts also become more visible. During compliance testing and design verification, this additional noise can be the difference between a validated eye pattern and costly rework.

Why Traditional De-Embedding Amplifies Noise in Oscilloscope Measurements

Modern oscilloscopes make great efforts to maintain low noise levels, but when using a de-embedding filter, both the signal and the oscilloscope noise are amplified simultaneously. As a result, signal edges are not as clean as they should be, and jitter measurements can be misleading.

On short traces, this may only amount to a loss of a few percent of margin. However, as data rates increase and channel lengths increase, the increased noise can cause carefully de-embedding traces to "slam shut," obscuring the true performance of your design.

QuietChannel Technology: Noise Reduction for Accurate Oscilloscope Measurements

Tektronix engineers realized that the bottleneck isn't just the channel, but also the way the instrument manages noise during de-embedding.

That's why the 7 Series DPO oscilloscope features QuietChannel™ technology—a patented combination of hardware and digital signal processing (DSP) that shapes the oscilloscope's noise floor, preventing it from growing uncontrollably.

Test Rig: A Bit Error Rate Generator (BERT) is used to inject PRBS test signals through channels of varying lengths. The 7 Series DPO oscilloscope with QuietChannel technology is used to measure the resulting signal.

Operating principle:

The oscilloscope's preamplifier applies a form of continuous-time linear equalization (CTLE) to boost high-frequency components before digitization. After the ADC, the DSP undoes this equalization, restoring a flat frequency response. This method preserves the signal while shaping the noise floor so that it remains lower at high frequencies.

The result is as if you were putting noise-canceling headphones on the oscilloscope: the de-embedded waveform suddenly becomes cleaner, jitter is reduced, and noise margins are more reliable.

Experimental Results: Improved Eye Patterns, Jitter, and Signal-to-Noise Ratio

Tektronix conducted a series of experiments to demonstrate the impact of QuietChannel technology at various channel lengths.

17-inch trace, 20 Gbps data rate. A modest increase in eye pattern height by 3% and width by 1% was observed. This improvement is minor, but sufficient to tip the scales in favor of passing the compliance test.

A 24-inch trace. The eye pattern height increased by 34%, and the width by 31%. Even more impressive, random jitter decreased by almost 40%: from 1.4 ps to 860 fs.

A 31-inch trace with a data rate of 16 Gbps. The eye pattern height more than doubled, and the signal-to-noise ratio at high frequencies improved by 5 dB.

In other words, the longer and more lossy your channel, the greater the impact of QuietChannel technology.

Benefits of QuietChannel Technology for Engineers

For compliance testing, these improvements mean greater confidence that a device that should pass does pass, and one that should fail does fail. For design verification, this means faster debug, fewer false failures, and higher yields in manufacturing.

Instead of struggling with measurement system noise, you can finally see the real behavior of your signal.

Accuracy and Clarity in High-Speed ​​Testing and Debug

QuietChannel technology isn't just another filter: it's a rethinking of how oscilloscopes manage noise in de-embedding environments. By shaping the noise floor itself, the Tektronix 7 Series DPO oscilloscope makes testing lossy channels more accurate, more reliable, and more convenient for engineers.

If you're working with serial links running at 16, 20, or even 28 Gbps, QuietChannel technology may be the extra clarity you've been missing.