Precision Matters: Why the LSK389 Remains the Benchmark in Ultra-Low Noise JFET Design

When it comes to designing ultra-sensitive analog systems, noise performance isn’t a feature—it’s a necessity. At Linear Systems, we understand the critical role that low-noise discrete components play in high-performance signal chains. That’s why our LSK389 Series Ultra-Low Noise, Monolithic Dual N-Channel JFET continues to set the standard for analog engineers across the globe.

100% Noise Tested – The Industry First

Originally re-released in 2020, the LSK389 is now 100% noise tested to guarantee it meets or exceeds both 1/f and broadband noise specifications. Using the world’s only large-scale sub-nanovolt testing capability, Linear Systems screens each unit to ensure:

No burst noise (RTN or popcorn)
Ultra-low noise performance down to 1.3nV/√Hz (typ)

Whether you're building high-end audio equipment, ultra-sensitive sensors, or low-noise op amps, you can rely on consistent, production-grade noise performance.

Trusted in Underwater Acoustic Systems

The LSK389 and its single-device counterpart, the LSK170, are widely used in underwater acoustic applications where extremely low-noise signal amplification is essential. These applications include:

Sonobuoys used in anti-submarine warfare (ASW)
Towed array sonar systems for naval surveillance
Hydrophones for marine research and underwater audio detection
Underwater modems and transducers for acoustic communication and navigation
Passive and active sonar systems used in defense and industrial marine applications

In all of these systems, signals travel farther and faster underwater than through air, and JFET-based amplifier circuits are required to cleanly capture and process those signals. The LSK389’s ultra-low noise, tight matching, and high input impedance make it a top choice for these precision front-end amplifiers that are vital to sonar and underwater communications equipment.

Why the LSK389?

The LSK389 isn’t just another low-noise JFET. Its monolithic interleaved dual construction provides superior IDSS matching, better thermal tracking, and performance advantages that discrete or non-monolithic dual JFETs can’t match.

Key Features: