August 27, 2009 -- Noise is a common and pervasive problem in electronics design and debug. At one time or another, almost every designer and debugger of electrical circuits will spend some time dealing with noise, either finding its source to fix it or reducing its impact on measurements. Noise can come from countless internal or external sources, often obscuring signals of interest.

Noise can make it difficult to perform measurements on a millivolt-range signal, such as in a radar transmission or heart-rate monitor. Another noise-related challenge is finding the true voltage of a signal. Moreover, noise may increase jitter, making it difficult to perform timing measurements.

Or there are times when you need a clean, noise-free trace to focus on the intended signal in a design. Other times, a clean trace is useful for reports and documentation to clearly show how a design works. Noise is pervasive in nearly all electrical design and debug work, though, so modern oscilloscopes offer filters to help reduce unwanted noise in measurements—and each filtering approach has its own pros and cons.

By Randy White. (White is serial applications technical marketing manager Tektronix, Inc.)