Lab equipment that measures frequency response should produce a flat noise profile when measuring a known flat white noise generator. Using white noise in this fashion can quickly expose unexpectedīehavior such as weird frequency spurs, strange harmonics, and undesirable frequency response artifacts.įurthermore, a white noise generator allows a careful engineer to test a tester. The expected response of the DUT to white noise is frequency-shaped noise.

Using more averaging and longer acquisition times produces a more accurate output response across the frequency range of interest. Simply connect the DUT output to a spectrum analyzer and watch. In this case, there is no need for expensive or complex swept sine wave generators. Imposing white noise at the input of a device under test (DUT) can quickly produce an overview of the frequency response over an entire frequency range. Testing fewer discrete frequencies can be faster, but increases the risk of skipping over critical frequencies where high Q phenomena reside.Ī white noise generator is simpler and faster than a swept sine wave because it effectively produces all frequencies at the same time with the same amplitude. A processor, DAC, and some complex, precise filtering can produce relatively clean sine waves, but for each frequency step, the system must settle, making slow work of sequential full sweeps featuring many frequencies. Extremely low frequency sine waves (below 10 Hz) are difficult to produce cleanly. Input sweeps can be composed of discrete input frequencies or a swept sine.

The outputs of many circuits can be characterized by sweeping the input signal across a range of frequencies and observing the response of the design. Nevertheless, there are cases where a well-characterized source of noise with no other signal is entirely the desired output.Ĭircuit characterization is such a case.

Noise in electrical circuits is typically the enemy, and any self-respecting circuit should output as little noise as possible. Pocket-Size White Noise Generator for Quickly Testing Circuit Signal ResponseĬan you produce a frequency spectrum for all frequencies at the same time? Answer:

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