Tektronix Oscilloscope Basics丨Signal Integrity Significance丨

The significance of signal integrity

Key to any good oscilloscope system is the ability to accurately reconstruct waveforms, a capability known as signal integrity. A Tektronix oscilloscope is like a camera; it captures an image of the signal that can then be viewed and interpreted. At the heart of signal integrity are two key issues:

1. When filming, is the image captured an accurate representation of what actually happened? Is the image clear or blurry?

2.How many such accurate pictures can be taken per second?

The various systems and performance features of a Tektronix oscilloscope combine to impact its ability to provide the highest signal integrity. Probes also impact the signal integrity of the measurement system. Signal integrity impacts many electronic design disciplines. But until a few years ago, it was not a big issue for digital designers. Designers could rely on logic circuits that operated like Boolean circuits. At the time, RF designers did not have to worry about the noisy, uncertain signals that occurred in high-speed circuits. Digital systems switched slowly, and signals settled in a predictable manner. Since then, processor clock rates have increased by several orders of magnitude. Computer applications such as 3D graphics, video, and server I/O require large amounts of bandwidth. Most of today's telecommunications equipment is digitally based and similarly requires massive bandwidth. Digital high-definition television is no exception. The current generation of microprocessor devices processes data at rates as high as 2GS/, 3GS/, and even 5GS/s (gigasamples per second), and some DDR3 memory devices use clocks in excess of 2GHz and data signals with rise times of 35ps. Importantly, the speed increase has trickled down to common IC devices used in automobiles, consumer electronics, machine controls, and a variety of applications.

The rise time of a signal in a processor running at a 20MHz clock rate is similar to that of a signal in an 800MHz processor. Designers have pushed performance boundaries, and in fact, almost every design is a high-speed design. Without certain preventative measures, high-speed issues can creep into otherwise traditional digital designs. If a circuit experiences intermittent failures or encounters errors at extreme voltages and temperatures, there may be some hidden signal integrity issues. These issues can affect product development cycles, product reliability, EMI compliance, and more. These high-speed issues can also affect the integrity of the serial data stream in the system, requiring some way to correlate specific patterns in the data with characteristics observed in the high-speed waveform.