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< Back Design Specs for JFETs Introduction Junction field effect transistors (JFETs) are used and are useful in many different circuit topologies. Because these devices function as voltage controlled current sources (VCCS) as opposed to current controlled current sources (CCCS), they offer designers certain flexibilities in designs not available when using bipolar transistors (which are CCCS devices). JFETs can also be used as voltage controlled variable resistors and voltage-controlled switches. JFETs have extremely high input impedances (on the order of giga-ohms) and extremely low input leakage currents (on the order of pico-amps). Selected parts are designed to have excellent performance in high and very high frequency (VHF) circuits. Read More

Linear Systems designs and manufactures the highest-performance line of monolithic dual JFETs in the industry. Contact us for a quote! Back LSK489 Series: Precision Dual JFETs LOW CAPACITANCE MONOLITHIC DUAL N-CHANNEL JFET The LSK489 is the industry’s lowest input capacitance and low-noise monolithic dual N-Channel JFET. Low input capacitance substantially reduces intermodulation distortion. In addition, these dual JFETs feature tight offset voltage and low drift over temperature range, and are targeted for use in a wide range of precision instrumentation and sensor applications. This part is available in the TO-71 6L, SOIC 8L, SOT-23 6L and DFN 8L package, as well as in die form. Advanced screening options are available for our diverse product lineup, featuring JFETS, Bipolar transistors, MOSFETs, current regulators, and Diodes. Our special screening covers all the parameters listed in the standard datasheet, including comprehensive package pin-out. Connect with our experienced technical team to discuss your specific needs and tailor your requirements—email us at support@linearsystems.com or call (510) 490-9160. MOQ applies to these specialized services. Ordering Information Below are the options you have when ordering this part series: LSK489A TO-71 6L RoHS LSK489B TO-71 6L RoHS LSK489A SOIC 8L RoHS LSK489B SOIC 8L RoHS LSK489A SOT-23 6L RoHS LSK489B SOT-23 6L RoHS 489 DFN 8L RoHS LSK489A Die LSK489B Die Datasheet Spice Model Application Notes

< Back AEA Linear Systems Mar 17, 2023 AEA’s Ribbon Microphones & Linears’ JFETs AEA When John Kurlander sought to capture the vast array of sound for the Lord of the Rings movies, he turned to Wes Dooley and his ribbon microphones. And for years, when Wes needed ultra-low-noise semiconductors to build and amplify those microphones, he turned to Linear Systems, Inc. “Linear Systems has kept that tradition going of making parts that are competitive with the [discontinued Toshiba] SK170s and 389s,” Dooley said in a recent interview. “And that gives us the ability to make compact, high-performance audio products.” “We make the quietest ribbon mic in the world, the A440, and the higher SPL A840. Both of them use the [Linear Systems] LSK389, for the output drivers and their current supply,” Dooley said. Dooley's company, Audio Engineering Associates (AEA), also uses the LSK389 in front ends of its RPQ and RPQ 500 preamplifiers, which were designed for use with ribbon microphones. AEA's microphone business started with ribbon mics for classical music used as movie scores. “John Kurlander did all three Lord of the Rings using AEA mics on strings left and right almost as strong in the mix as the main orchestra mics,” Dooley said. “When you work with such people, one really learns to be of service.” AEA's customer list reads like a Who's Who of Grammy and Academy Award-winning recording engineers and artists. Among the many examples, sound engineer Michael Bishop, winner of eight Grammy awards, extensively uses AEA's A840 microphones and AEA preamps for his recordings. Shawn Murphy, who's worked on over 330 films and won an Academy award for Jurassic Park, also relies on AEA's preamps and microphones. One of the best parts of AEA's website is the long list of reviews and mentions by users . Dooley, a lifelong ribbon microphone enthusiast and developer, got into the business by repairing ribbon mics built by RCA during the golden age of radio. “We started servicing mics in '76 when RCA shut down making them,” he said. “Many of our favorite RCA designs were from the mid '30s, when a designer's foremost tool was listening to live music. Critical listening was the gold standard as acoustical measurements were cumbersome.” “We've adopted that approach, which is: musicality trumps metrics. The mic has to sound good to people in the music business,” Dooley said. “If it doesn't sound good, measurements don't matter. Once you have a mic that sounds good to people who have experienced ears, then measurements are very important, as they are the key to consistent production.” “So we first strive to make sure it sounds musical, and then we measure what it does,” Dooley said. “Because, as one of my mentors, Richard Heyser, said, if it measures well but doesn't sound right, then you're measuring the wrong things. Often you find you don't know what the right thing to measure is. Over time you discover what those metrics might be. Ultimately, it's a matter of how it sounds. Since we come from an acoustic music tradition, it's pretty simple: you put the mic in front of live music, and compare that live sound with the reproduction, to see how close it is.” Dooley told the story of working with legendary bluegrass fiddle player/violinist Richard Greene. Greene, along with his wife, a violinist with the LA Chamber Orchestra, recorded samples using over 20 microphones. “The next day, when they had 'fresh ears,' they listened to all the recordings and said the one made using our ribbon microphones was the best,” Dooley said. “And that's what we try for, for the musicians to experience that this is the closest they've ever heard to an actual performance.” Asked to comment for this article, Greene had high praise for Dooley and his microphones. “Silky, smooth, best violin sound I ever heard, Wes is amazing and his tech support and other free maintenance are over the top,” Greene wrote. “I will never have any use for any other mic on my violin. I have the AEA 440.” Dooley said this close interaction with artists drives how he builds microphones and preamps. “The whole thing,” he said, “is to build tools they need. That is the key to survival for a small business doing high-performance products.” The LSK389 “is a very good part for manufacturing,” Dooley said. AEA uses the “C” grade of the LSK389. “We started with the 'A' [grade], but then we realized it didn't make any difference for what we were doing,” he said. The LSK389 is graded by IDSS ; all three grades have the same ultra-low-noise characteristics. The Linear Systems LSK389 part used by AEA is an ultra-low-noise junction field effect transistor. Linear System Founder and CEO John H. Hall began working on a JFET similar to Toshiba's 2SK389 about the time that the Japanese company began to discontinue the device 10 years ago. “Toshiba kept its production process for the 389 secret, so we had to figure out on our own how to build something to the same specification, which was extremely difficult,” Hall said. Expertise brought to Linear Systems is based on processes and products Hall developed since 1962 at Amelco, Union Carbide, Intersil, and Micro Power Systems. Hall, a protégé of Silicon Valley legend Dr. Jean Hoerni, was the director of IC Development at Union Carbide, co-founder and vice president of R&D at Intersil, and founder/president of Micro Power Systems. Much of Linear Systems' current development work focuses on lower-noise JFETs. The production techniques Hall conceived to squeeze the last bit of noise out of the 389 led to development of another part, the LSK489. The LSK489 has less transconductance than the 389, and though this increases noise slightly, it makes the part easier to design into new circuits. “While the 389 is the perfect part for some users, such as Wes Dooley, who need the lowest noise levels in existence, we found that the high gate-to-drain capacitance of the 389 caused problems for some of our other customers,” Hall said. “Building a high transconductance part, such as the 389, formed part of the basis for providing ultra-low-noise levels, but the high input capacitance causes intermodulation distortion in some higher-frequency applications,” Hall said. “Since we had created some advanced processing techniques to make the 389, we decided to go back and look at creating a part with lower capacitance using the same processes.” Though Dooley's ribbon microphone and other devices take advantage of the 389's low noise level, other developers could tolerate a slightly higher noise level in a part that has much lower input capacitance due to a lower transconductance, Hall said. The lower capacitance and other features make the LSK489 a lower-noise, functional replacement for Linear Systems' LS840-series of JFETs, as well as the Siliconix U401-403 series. Dooley's precision ribbon microphones are perfect applications of the LSK389, Hall said. “Both ribbon microphones and JFETs are very difficult to design and build, but there's really no other way to achieve the level of performance needed than to do the work this way.” The circuit design work using the LSK389s was done for AEA by Fred Forssell of http://www.forsselltech.com . For more on Dooley's microphones, go to: http://www.ribbonmics.com Data sheets for the LSK389 and LSK489, the application notes for the LSK489, and a good paper on general JFET theory and use can be downloaded at: http://linearsystems.com .

Insights and Updates March 31, 2025 at 6:45:00 PM Jagdev Bariana: Chief Product Officer Linear Systems Promotes Jagdev Bariana to Chief Product Officer Read More January 13, 2025 at 8:00:00 PM Mike Ansberry: VP of Manufacturing and General Manager Mike Ansberry Named VP of Manufacturing and General Manager at Linear Systems Read More December 25, 2024 at 8:00:00 PM Linear Integrated Systems Expands Custom Testing Services to Provide Designers Greater Optimization and Flexibility Linear Integrated Systems (Linear Systems) is pleased to announce the immediate availability of Expanded Custom Testing Services for all its Small Signal Discrete Products. These services allow designers to tailor product specifications to meet specific design requirements, empowering them to optimize performance and enhance flexibility. Read More November 21, 2024 at 8:00:00 PM Jaime Cook: VP of Operations & Market Development Jaime Cook Appointed VP of Operations & Market Development at Linear Systems, Inc. Read More October 7, 2024 at 7:00:00 PM What are Current Regulating Diodes Current regulating diodes, also known as constant current diodes or current limiting diodes, are electronic components that control the amount of electrical current flowing through a circuit. They work by maintaining a constant voltage across themselves despite changes in the load resistance. Read More October 7, 2024 at 7:00:00 PM Specialty Semiconductor - Linear Systems Linear Systems has designed, manufactured and distributed the best specialty semiconductors in their respective classes since 1987. Working in three Silicon Valley fabrication facilities, our components are world leaders in applications ranging from military underwater listening to the largest space telescope camera in existence. Read More September 26, 2024 at 7:00:00 PM BIFET Amplifiers BIFET amplifiers are a type of operational amplifier (op-amp) that use bipolar junction field-effect transistors (BJFETs) as their input stage. Read More July 25, 2024 at 2:45:00 PM Designing Audio Circuits and Systems Exploring Phono Preamp Circuits with Bob Cordell’s New Book Read More July 16, 2024 at 6:45:00 PM Bipolar Transistors Linear Systems’ Monolithic Dual NPN and PNP transistors consist of two transistors on the same piece of silicon resulting in better matching and better performance over temperature. These parts are designed for general purpose amplifier and switching applications. Read More July 9, 2024 at 7:45:00 PM MOSFETs Linear Systems’ small signal MOSFETs consist of two MOSFETs on the same piece of silicon resulting in better matching and better performance over temperature. Read More June 17, 2024 at 7:20:00 PM DMOS High Speed Switches by Linear Systems The Linear Systems family of DMOS devices is designed to handle a wide range of video, fast ATE, telecom and other analog switching applications. These components are capable of ultrafast switching speeds (tr = 1 ns, tOFF = 3 ns) and excellent transient response. Thanks to reduced parasitic capacitances, our DMOS can handle wideband signals with high off-isolation and minimum crosstalk. Read More June 10, 2024 at 7:15:00 PM FAST SAMPLE AND HOLD In this interesting design, a strobe pulse sets the sample mode. Here's how it works: Read More June 3, 2024 at 6:45:00 PM Linear Systems Capabilities Statement Who we are and what we do Read More May 30, 2024 at 7:00:00 PM What is a JFET? JFETs are three-terminal semiconductor devices that can be used as electronically controlled switches or resistors, or to build amplifiers. Read More March 17, 2023 at 3:00:00 PM Military Sensors White Paper Linear Systems' White Paper Describes Lowest Noise Amplification for Sensor Signal Chains Read More March 17, 2023 at 3:00:00 PM LSK170 Press Release Direct Replacement for Toshiba 2SK170 Read More March 17, 2023 at 3:00:00 PM John H. Hall In Remembrance of Linear Systems' Founder Read More March 17, 2023 at 3:00:00 PM Cloud Microphones Keeping the Family Business Going Read More March 17, 2023 at 3:00:00 PM LTspice Press Release Linear Systems' JFETs in LTspice Read More March 17, 2023 at 3:00:00 PM SD5400/SD5000 Introducing Family of Quad N-channels Read More March 17, 2023 at 3:00:00 PM Testing Capability New Low-Noise Semiconductor Testing Capability Read More March 17, 2023 at 3:00:00 PM LSK389 Press Release Ultra-Low Noise, Monolithic Dual, N-Channel JFET Read More March 17, 2023 at 3:00:00 PM Largest Digital Camera Engineering the World’s Largest Digital Camera Read More March 17, 2023 at 3:00:00 PM LSJ689 Press Release Ultra Low Noise P-Channel Dual JFET Read More March 17, 2023 at 3:00:00 PM LS26VPS/VNS Press Release New JFET Voltage-Controlled Resistors Read More March 17, 2023 at 3:00:00 PM High Temp Products High Temp Discrete Products Read More March 17, 2023 at 3:00:00 PM DMOS Product Line DMOS Product Line Acquired from Vishay/Siliconix Read More March 17, 2023 at 3:00:00 PM App Note by Dimitri Danyuk Headphone Amplifier Evaluation Board Read More March 17, 2023 at 3:00:00 PM Ansberry Named VP Michael Ansberry - VP for Process Engineering. Read More March 17, 2023 at 3:00:00 PM LSK489 Press Release Low-Capacitance Dual N-Channel JFET Read More March 17, 2023 at 3:00:00 PM Burning Amp Festival Burning Amp Festival - A DIY Audio Gathering Read More March 17, 2023 at 3:00:00 PM AEA AEA’s Ribbon Microphones & Linears’ JFETs Read More March 17, 2023 at 3:00:00 PM Millions of Devices in Stock! LS844 Monolithic Dual Small-Signal JFET, 3N163 Small-Signal MOSFET, LS320 BiFET and Many More! Read More

Linear Systems designs and manufactures the highest-performance line of monolithic dual JFETs in the industry. Contact us for a quote! Back LSK589 LOW NOISE, LOW CAPACITANCE MONOLITHIC DUAL N-CHANNEL JFET The LSK589 is a Low Noise, Low Capacitance, Monolithic Dual N-Channel JFET. This part is targeted for use in a wide range of precision instrumentation and sensor applications. It is available in the TO-71 6L, SOIC 8L, SOT-23 6L and DFN 8L package, as well as in die form. Advanced screening options are available for our diverse product lineup, featuring JFETS, Bipolar transistors, MOSFETs, current regulators, and Diodes. Our special screening covers all the parameters listed in the standard datasheet, including comprehensive package pin-out. Connect with our experienced technical team to discuss your specific needs and tailor your requirements—email us at support@linearsystems.com or call (510) 490-9160. MOQ applies to these specialized services. Ordering Information Below are the options you have when ordering this part series: LSK589 TO-71 6L RoHS LSK589 SOIC 8L RoHS LSK589 SOIC 8L RoHS LSK589 SOT-23 6L RoHS 589 DFN 8L RoHS LSK589 Die Datasheet Spice Model Application Notes

HIGH INPUT IMPEDANCE, N-CHANNEL JFET AMPLIFIER < Back LS5301 HIGH INPUT IMPEDANCE, N-CHANNEL JFET AMPLIFIER The LS/PF/SST5301 Series Single, High Input Impedance, N-Channel JFET Amplifier is a direct replacement for the Fairchild equivalent part. It is ideal for Very High Input Impedance Applications. Available in TO-72 4L RoHS, TO-92 3L RoHS and SOT-23 3L RoHS package, as well as in die form. Advanced screening options are available for our diverse product lineup, featuring JFETS, Bipolar transistors, MOSFETs, current regulators, and Diodes. Our special screening covers all the parameters listed in the standard datasheet, including comprehensive package pin-out. Connect with our experienced technical team to discuss your specific needs and tailor your requirements—email us at support@linearsystems.com or call (510) 490-9160. MOQ applies to these specialized services. Ordering Information Below are the options you have when ordering this part: PF5301 TO-92 3L RoHS LS5301 TO-72 4L RoHS SST5301 SOT-23 3L RoHS LS5301 Die Datasheet Spice Model Application Notes

MONOLITHIC DUAL, NPN TRANSISTOR < Back IT124 MONOLITHIC DUAL, NPN TRANSISTOR The IT124 Monolithic Dual, NPN Transistor, Super Beta is a direct replacement for th Intersil IT124. It is ideal for Small Signal Transistor, Super Beta, Amplifier & Switching Applications. It is available the in TO-71 6L RoHS, TO-78 6L RoHS, PDIP 8L ROHS and SOIC 8L RoHS package, as well as bare die. Advanced screening options are available for our diverse product lineup, featuring JFETS, Bipolar transistors, MOSFETs, current regulators, and Diodes. Our special screening covers all the parameters listed in the standard datasheet, including comprehensive package pin-out. Connect with our experienced technical team to discuss your specific needs and tailor your requirements—email us at support@linearsystems.com or call (510) 490-9160. MOQ applies to these specialized services. Ordering Information Below are the options you have when ordering this part series: IT124 TO-71 6L RoHS IT124 TO-78 6L RoHS IT124 PDIP 8L RoHS IT124 SOIC 8L RoHS IT124 Die Datasheet Spice Model Application Notes

< Back LSK389 App Note Introduction The LSK389 is the industry’s lowest noise Dual N-Channel JFET, 100% tested, guaranteed to meet 1/f and broadband noise specifications, while eliminating burst (RTN or popcorn) noise entirely. The product displays high transconductance and very good matching. It is the JFET of choice for low noise applications, especially those requiring a differential amplifier input stage. Read More

MONOLITHIC DUAL, PNP TRANSISTOR < Back IT130 Series MONOLITHIC DUAL, PNP TRANSISTOR The IT130 Series Monolithic Dual, PNP Transistor is a direct replacement for the Intersil IT130 Series. It is ideal for Small Signal Transistor Amplifier & Switching Applications. It is available the in TO-71 6L RoHS, TO-78 6L RoHS, PDIP 8L ROHS and SOIC 8L RoHS package, as well as bare die. Advanced screening options are available for our diverse product lineup, featuring JFETS, Bipolar transistors, MOSFETs, current regulators, and Diodes. Our special screening covers all the parameters listed in the st andard datasheet, including comprehensive package pin-out. Connect with our experienced technical team to discuss your specific needs and tailor your requirements—email us at support@linearsystems.com or call (510) 490-9160. MOQ applies to these specialized services. Ordering Information Below are the options you have when ordering this part series: IT130A TO-71 6L RoHS IT130 TO-71 6L RoHS IT131 TO-71 6L RoHS IT132 TO-71 6L RoHS IT130A TO-78 6L RoHS IT130 TO-78 6L RoHS IT131 TO-78 6L RoHS IT132 TO-78 6L RoHS IT130A PDIP 8L RoHS IT130 PDIP 8L RoHS IT131 PDIP 8L RoHS IT132 PDIP 8L RoHS IT130A SOIC 8L RoHS IT130 SOIC 8L RoHS IT131 SOIC 8L RoHS IT132 SOIC 8L RoHS IT130A Die IT130 Die IT131 Die IT132 Die Datasheet Spice Model Application Notes

TIGHTLY MATCHED, MONOLITHIC DUAL, NPN TRANSISTOR < Back LS310 Series TIGHTLY MATCHED, MONOLITHIC DUAL, NPN TRANSISTOR The LS310 Series, Tightly Matched, Monolithic Dual, NPN Transistor is a direct replacement for Analog Devices MAT series and National LM3494 series. It is ideal for Tight Matching, Small Signal Transistor Amplifier & Switching Applications. It is available the in TO-71 6L, TO-78 6L, PDIP 8L, SOIC 8L, SOT-23 6L and DFN 8L package, as well as bare die. Advanced screening options are available for our diverse product lineup, featuring JFETS, Bipolar transistors, MOSFETs, current regulators, and Diodes. Our special screening covers all the parameters listed in the standard datasheet, including comprehensive package pin-out. Connect with our experienced technical team to discuss your specific needs and tailor your requirements—email us at support@linearsystems.com or call (510) 490-9160. MOQ applies to these specialized services. Ordering Information Below are the options you have when ordering this part series: LS310 TO-71 6L RoHS LS311 TO-71 6L RoHS LS312 TO-71 6L RoHS LS313 TO-71 6L RoHS LS310 TO-78 6L RoHS LS311 TO-78 6L RoHS LS312 TO-78 6L RoHS LS313 TO-78 6L RoHS LS310 PDIP 8L RoHS LS311 PDIP 8L RoHS LS312 PDIP 8L RoHS LS313 PDIP 8L RoHS LS310 SOIC 8L RoHS LS311 SOIC 8L RoHS LS312 SOIC 8L RoHS LS313 SOIC 8L RoHS LS310 SOT-23 6L RoHS LS311 SOT-23 6L RoHS LS312 SOT-23 6L RoHS LS313 SOT-23 6L RoHS 311 DFN 8L RoHS 312 DFN 8L RoHS LS310 Die LS311 Die LS312 Die LS313 Die Datasheet Spice Model Application Notes

< Back John H. Hall Linear Systems Mar 17, 2023 In Remembrance of Linear Systems' Founder John H. Hall FREMONT, CA - Linear Systems, Inc., a California developer and manufacturer of small-signal discrete semiconductors, announced the passing of its founder and CEO, John H. Hall. Hall was a pioneer in the development of low power CMOS integrated circuits. He founded or co-founded multiple innovative Silicon Valley companies, including Intersil, MicroPower Systems, and Integrated Wave Technologies, Inc., in addition to Linear Integrated Systems. Over the course of his career, Hall received 21 patents covering advanced semiconductor processes and designs. Hall was a protégé of Dr. Jean Hoerni, one of the "Traitorous Eight" who left Shockley Semiconductor Laboratory and co-founded rival Fairchild Semiconductor. In turn, many of Hall's former employees such as David Fullagar went on to become major Silicon Valley contributors. "John's professional contributions over a 60-year career were matched only by his generosity toward the people around him," said Cindy L Johnson,. "He is greatly missed by his family and friends." In accordance with Hall's wishes Linear Integrated Systems will continue its work as a world-class developer and producer of specialized discrete semiconductors, A year before Mr. Hall died he appointed Cindy L. Johnson as president. In 2014 the board of directors appointed Cindy L. Johnson as CEO. Chief Executive Officer Cindy L. Johnson Cindy L. Johnson has 37 years of Silicon Valley experience, starting her career with MicroPower Systems in 1977. Johnson began her career working for John H. Hall at Micro Power Systems and in 1986 was a co-founder of Linear Integrated Systems, Inc. Johnson has served as president and chief financial officer (CFO) of Linear and will continue as CFO in addition to assuming the position of CEO.