Linear Systems Learning Series: Understanding 1/f Noise: Why Low-Frequency Noise Matters

Not all noise is created equal.

When engineers compare low-noise devices, they often focus on the 1 kHz noise specification. While that's an important benchmark, it doesn't tell the whole story.

At lower frequencies, many semiconductor devices exhibit 1/f noise, also known as flicker noise. As frequency decreases, this noise increases, making it especially important in applications that measure slow-changing or very small signals.

Examples include:

• Precision instrumentation

• Medical electronics

• Seismic sensors

• Hydrophones

• Geophysical equipment

• Condenser microphone preamplifiers

• High-resolution data acquisition systems

In these applications, low-frequency noise can limit measurement resolution long before broadband noise becomes the dominant factor.

That's why engineers evaluate both broadband noise and 1/f noise when selecting input devices for precision analog front ends.

Devices such as the LSK389 are designed with exceptionally low broadband and low-frequency noise, making them well suited for demanding analog applications where preserving weak signals is critical. The LSK389 is specifically designed for ultra-low-noise applications and is 100% tested to meet its 1/f and broadband noise specifications.

Engineering Tip

If your circuit measures slow-changing signals, don't stop at the 1 kHz noise specification. Evaluate low-frequency (1/f) noise as well—it can have a significant impact on real-world performance.

Linear Systems Learning Series: Helping engineers better understand precision analog design.