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:

• Four IDSS grading options for design flexibility

• Tight matching: IVGS1-2 ≤ 15mV max

• High gain: Gfs = 20mS (typ)

• Low capacitance: 25pF (typ)

• Available in SOIC-8 and TO-71 packages

Part of a Complete Low-Noise JFET Family

The LSK389 is the cornerstone of our low-noise JFET lineup:

• LSK170 – N-channel single version

• LSJ74 – P-channel equivalent

• LSK489 – N-channel dual (lower capacitance, slightly higher noise)

• LSJ689 – P-channel dual version

Each is part of Linear Systems' Improved Standard Products®, offering lower noise than competitors' equivalents.

📞 For more information, contact us at (510) 490-9160 or sales@linearsystems.com🌐 Visit: www.linearsystems.com