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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

🔬 Exploring the Reversed Sziklai Pair  🔍 Check out this clever hybrid design that flips the script on traditional amplifier topology!   📌 What makes it interesting? – Bipolar input = lower input impedance– Wide input range: 0.1mV to 12mV– Frequency response: 100Hz – 620kHz– Voltage gain ≈ 100 | Current gain ≈ 1.5– Distortion as low as 0.89%   This design demonstrates how blending technologies can lead to simple yet effective results in audio and signal processing. A great example of innovation through circuit simplicity.   📄 Source: https://iopscience.iop.org/article/10.1088/1757-899X/225/1/012152/pdf   Explore industry-leading JFETs at: www.linearsystems.com 💡 Follow us for more #FETFriday insights! #AnalogDesign #JFET #BipolarTransistors #AudioEngineering #CircuitDesign #ElectronicsInnovation

Linear Integrated Systems headphone amplifier evaluation board is a complete, low-power stereo audio amplifier for high-fidelity line-level output and headphone applications. It consists of Linear Integrated Systems JFETs along with a number of other parts mounted on a circuit board. Linear Integrated Systems headphone amplifier evaluation board includes the following features: Stereo, single ended input and single ended output 400 mW output power into 100Ω Wide frequency response (10Hz?200kHz; ?1dB) Voltage gain 5 (14dB) Low distortion (THD+N is less than 1% at 10Hz?20kHz at 5Vrms into 100Ω and less than 0.1% from 10 Hz to 20 kHz at 1Vrms into 100Ω load) Short circuit protection Pop reduction (slow start) circuit Defeatable cross feed circuit Volume control Overvoltage and reverse polarity power protection Audio input and output connections: left and right RCA phono jack inputs, ¼” stereo phone jack output External 9V–16V supply input External power supply connector: power jack, inside diameter 2.1mm, outside diameter 5.5mm

Linear Systems specializes in crafting premium semiconductors, enabling customers to create top-tier products. Our product range includes Ultra-Low-Noise JFETs, DMOS Switches, Bipolar Transistors, BIFET Amplifiers, Regulating Diodes, MOSFETs, and more. Utilizing patented processes, Linear Systems delivers high-performance discrete semiconductors. Our primary markets span Audio, Hybrids, Industrial Controls, Instrumentation, Medical Electronics, Military, Space, and Test & Measurement. About Us Our Story Linear Systems was founded in 1987 by John H. Hall. Expertise brought to Linear Systems is based on processes and products developed at Amelco, Union Carbide, Intersil and Micro Power Systems by John H. Hall. Linear Integrated Systems develops and produces the highest performance semiconductors of their kind in the industry. Our goal is to enable our customers to build world-class products based upon our parts. Our product line consists of: Ultra-Low-Noise N-Channel and P-Channel Dual and Single JFETs, High Speed Lateral DMOS Switches, Bipolar Transistors, BIFET Amplifiers, Current Regulating Diodes, Low Leakage Diodes, MOSFETs, PhotoFETS, and Voltage Controlled Resistors. Linear Integrated Systems uses patented and proprietary processes and designs to create its high performance discrete semiconductors. Our primary markets are: Audio; Hybrids; Industrial Controls; Instrumentation; Medical Electronics; Military; Space; and Test & Measurement. Our design and fabrication facilities are located in the heart of California’s Silicon Valley. Let’s Work Together 4042 Clipper Court Fremont, CA 94538-6540 USA E-Mail: info@mysite.com Tel: 510-490-9160, First Name Last Name Email Message Thanks for submitting! Send

Discover an extensive array of application notes and white papers authored by the talented minds at Linear Systems, as well as contributions from our esteemed colleagues and friends. Immerse yourself in our carefully curated selection to stay informed and inspired. Articles & Books This is a space to tell users about yourself and your business. Let them know who you are, what you do, and what this website is all about. Double click to start editing. Articles FET Principles and Circuits, Part 1 to 4, by Ray Martson, Nuts and Volt 5/2000 Ray Marston Read More JFETs The New Frontier Part 1 Erno Borbely Read More Books Designing with Field Effect Transistors (Second Edition) 1990 ISBN 007057537-1 FET Technology and Applications 1989 ISBN 0824780507 View Read More Analog Circuit Design - A Tutorial Guide to Applications and Solution Analog Circuit Design, Volume 2 – Immersion in the Black Art of Analog Design Analog Circuit Design, Volume 3 – Design Note Collection View Read More An Introduction to Field Effect Transistors-by J. Watson PHD, University of Wales, Swansea-1970 Designing with Field Effect Transistors (First Edition) 1981 ISBN 9780070574496 View Read More Some Tips on Making a FETching Discrete Amplifier View Read More Designing Audio Power Amps, 2010, ISBN 007164024X The Audio Power Amplifier Design Handbook (Fifth Edition) View Read More Designing Audio Power Amps, 2010, ISBN 007164024X View Read More Piezoelectric Accelerometers with Integral Electronics includes noise analysis of JFET and MOSFET amplifier circuits ISBN 978-331908-0772 View Read More

Linear Systems has been designing, manufacturing, and distributing high-performance JFET Amplifiers, DMOS Switches, Current Regulating Diodes, Bipolar Transistors, and JFET Switches since 1987. Our specialty semiconductors are recognized as the best in their class for precision, reliability, and performance. Building Excellence, One Part at a Time Since 1987, Linear Systems has been a leader in designing and manufacturing specialty semiconductors. Operating from three Silicon Valley fabrication facilities, we serve a wide range of industries, including defense, aerospace, professional audio, and more. Our components are integral to applications such as military underwater surveillance, space telescope cameras, high-fidelity audio equipment, and advanced aerospace sensors. Our dedicated team is committed to delivering high-quality, reliable components, ensuring timely delivery to meet our customers' needs. View Products Tailored Solutions to Meet Your Exact Specifications Get Started Connect with our expert technical team to discuss your project today: Call (510) 490-9160 or Email support@linearsystems.com How We Help You At Linear Systems, we understand that every application has unique demands. That’s why we offer advanced screening and customization options across our full product range, including N-Channel and P-Channel JFETs, High-Speed N-Channel Lateral DMOS Switches, Single and Quad Current-Regulating Diodes, Ultra Low-Leakage Diodes, NPN and PNP Bipolar Transistors, N-Channel and P-Channel Small Signal MOSFETs, and BIFET devices. Our advanced screening process allows for precise parameter selection, covering all specifications listed in our standard data sheets, including detailed package pin-outs. Whether you need tighter tolerances, specific performance metrics, or custom sorting, we can tailor our parts to meet your exact requirements. Let’s build exactly what you need. High-Performance Components for Demanding Applications We specialize in precision analog components engineered for exceptional performance across the most demanding industries. Ultra-Low-Noise JFETs: Our flagship LSK series—including the LSK389 and LSK170—offers industry-leading ultra-low-noise N-Channel monolithic dual and single JFETs, trusted in the world’s most critical applications. The LSK series delivers outstanding low-noise performance at consumer-friendly prices. We also offer an extensive range of high-performance Improved Standard JFETs. High-Speed DMOS Switches: Our lateral DMOS switches set the standard for speed and reliability, featuring single and quad nanosecond switches—with or without protection diodes—for fast, precise switching applications. Ultra-Low-Leakage Diodes: The PAD/JPAD/SSTPAD series provides ultra-low-leakage diodes for designs requiring minimal reverse current. With leakage currents as low as -1 pA (PAD1), these diodes protect sensitive circuit inputs like op-amps, ADC analog inputs, analog multiplexers, and RS485 line receivers from over-current and over-voltage. Current-Regulating Diodes: Our SST500 series of current-regulating diodes ensures consistent performance in high-reliability environments such as test equipment, medical devices, and instrumentation. Utilizing JFET technology, these diodes simplify circuit integration while maintaining precision. From precision JFETs to specialized diodes and switches, Linear Systems delivers components that meet the highest standards of performance and reliability. Explore our: Low-Noise JFETS Explore our: Low Leakage Diodes & Current Regulating Diodes Explore our: High-Speed DMOS Switches