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< Back Current Regulating Diodes Introduction Abstract: Many analog circuit designs have the need for current regulation. Examples include circuits that process signals from sensors, circuits that amplify, and voltage reference or regulators. Current regulation can be referred to as a current source or a Norton device/equivalent circuit (cf. Thevenin equivalent circuit). Read More

< Back BIFET Amplifiers Linear Systems Sep 26, 2024 BIFET amplifiers are a type of operational amplifier (op-amp) that use bipolar junction field-effect transistors (BJFETs) as their input stage. Introduction BIFET amplifiers are a type of operational amplifier (op-amp) that use bipolar junction field-effect transistors (BJFETs) as their input stage. These types of amplifiers have been popular for many years because they offer low bias currents, high input impedance and excellent linearity. In this article, we will discuss the key features of BIFET amplifiers, how they differ from other op-amps, and some common applications where they are used. What is a BIFET Amplifier? As mentioned earlier, BIFET amplifiers use BJFETs as their input stage instead of traditional MOSFETs or BJTs. BJFETs are known for their high input impedance and low noise, making them suitable for use in audio amplifiers and other sensitive applications. One of the main advantages of BIFET amplifiers is their low bias currents, which can be as low as a few femtoamps (10^-15 amps). This allows for higher precision in measuring small signals without introducing additional error. How do BIFET Amplifiers Differ from Other Op-Amps? BIFET amplifiers have several key differences compared to traditional op-amps. These include: Input Stage: As mentioned earlier, BIFET amplifiers use BJFETs instead of MOSFETs or BJTs as their input stage. This allows for higher input impedance and lower bias currents. Biasing: BIFET amplifiers typically use a single positive power supply, unlike other op-amps which may require dual supplies. This makes them more convenient to use in certain applications. Output Stage: The output stage of a BIFET amplifier is usually a MOSFET or BJT, providing high output current and low output impedance. This allows for driving larger loads without significant signal loss. Applications of BIFET Amplifiers BIFET amplifiers are commonly used in audio applications due to their low noise and high linearity. They are also popular in medical and scientific instrumentation where precision measurements are required. Other applications of BIFET amplifiers include: Sensor Signal Conditioning: The high input impedance and low bias currents make BIFET amplifiers ideal for conditioning signals from sensors such as thermocouples, strain gauges, and photodiodes. Active Filters: BIFET amplifiers can be used to create active filters with better performance compared to traditional op-amps. They also have lower power consumption, making them suitable for battery-powered applications. Data Acquisition Systems: BIFET amplifiers are commonly used in data acquisition systems due to their low noise and high precision. They can amplify small signals from sensors before being digitized for processing. Conclusion BIFET amplifiers offer several advantages over traditional op-amps, making them suitable for a variety of applications. They provide high input impedance, low bias currents, and high output current capabilities. These features make BIFET amplifiers ideal for use in audio, sensor signal conditioning, active filters, and data acquisition systems. As technology continues to advance, we may see further improvements in BIFET amplifier design and their application in various industries. So, it is important to stay updated with the latest developments in this field to fully utilize the potential of BIFET amplifiers.

< Back What are Current Regulating Diodes Linear Systems Oct 7, 2024 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. 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. How do they work? A standard diode allows current to flow freely in one direction and blocks it in the other direction. In contrast, a current regulating diode has a larger depletion region and a lower reverse breakdown voltage, which allows for more precise control of the current flow. When used in series with a load, the current regulating diode maintains a stable voltage drop across itself by varying its own resistance depending on the current flow. This means that as the load resistance changes, the voltage drop across the diode remains constant and therefore maintains a consistent current flow. Applications Current regulating diodes are commonly used in circuits where stable and precise current control is necessary, such as in LED lighting systems, battery charging circuits, and laser diode drivers. They can also be used as protection devices to limit the amount of current flowing through sensitive components. In addition, these diodes are often utilized in adjustable power supplies to regulate the output current and prevent damage to connected devices. Types of Current Regulating Diodes There are two main types of current regulating diodes: Zener diodes and avalanche diodes. Zener diodes operate in the reverse breakdown region, where they maintain a constant voltage despite changes in current flow. This makes them ideal for use as voltage regulators. Avalanche diodes, on the other hand, operate in the avalanche breakdown region and are used for higher voltage applications. They have a steeper current-voltage characteristic compared to Zener diodes, allowing for more precise control of the current flow. Advantages and Disadvantages The main advantage of using current regulating diodes is their ability to provide stable and accurate current control without the need for additional external components. This saves space and simplifies circuit design. However, one disadvantage is that these diodes can be sensitive to changes in temperature, which can affect their current regulation capabilities. In addition, they have a limited maximum current handling capacity, so they may not be suitable for high power applications. Conclusion In conclusion, current regulating diodes are essential components in many electronic circuits where precise and stable current control is necessary. They come in various types and offer advantages such as simplicity of use and compact size. However, care must be taken when using these diodes to ensure proper operation under different conditions. With continued advancements in technology, it is likely that we will see further improvements and developments in the field of current regulating diodes. So next time you encounter a circuit that requires precise current control, consider using a current regulating diode to achieve optimal performance. With their unique properties and benefits, these diodes are sure to play a significant role in the future of electronics. With the ever-growing demand for more efficient and reliable electronic devices, it is important to have a thorough understanding of different electronic components such as current regulating diodes. By having knowledge about their operation, advantages and limitations, you can make informed decisions when designing circuits for various applications. So keep exploring and learning about these fascinating components and discover new ways to incorporate them into your designs.

DFN PACKAGE, SINGLE P-CHANNEL JFET SWITCH < Back 174DFN Series DFN PACKAGE, SINGLE P-CHANNEL JFET SWITCH The 174DFN Series Low On-Resistance, P-Channel JFET Switch is a direct replacement for the Fairchild and Siliconix-Vishay part series. It is ideal for low resistance, low operating current switching applications. Available in the DFN 8L 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 series: 174DFN 8L RoHS 175DFN 8L RoHS 176DFN 8L RoHS 177DFN 8L RoHS J174 TO-92 3L RoHS J175 TO-92 3L RoHS J176 TO-92 3L RoHS J177 TO-92 3L RoHS SST174 SOT-23 3L RoHS SST175 SOT-23 3L RoHS SST176 SOT-23 3L RoHS SST177 SOT-23 3L RoHS J174 Die J175 Die J176 Die J177 Die Datasheet Spice Model Application Notes

DFN PACKAGE, SINGLE N-CHANNEL JFET SWITCH < Back 4391DFN Series DFN PACKAGE, SINGLE N-CHANNEL JFET SWITCH 4391DFN Series Single, Low Noise, N-Channel JFET Switch is a direct replacement for the Siliconix-Vishay equivalent part. It is ideal for Low Noise, High Gain, Low resistance Switching and Amplifier Applications. Available in the DFN 8L RoHS, TO-92 3L RoHS, TO-18 3L RoHS and SOT-23 3L 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: PN4391 TO-92 3L RoHS PN4392 TO-92 3L RoHS PN4393 TO-92 3L RoHS 2N4391 TO-18 3L RoHS 2N4392 TO-18 3L RoHS 2N4393 TO-18 3L RoHS SST4391 SOT-23 3L RoHS SST4392 SOT-23 3L RoHS SST4393 SOT-23 3L RoHS 2N4391 DIE 2N4392 DIE 2N4393 DIE Datasheet Spice Model Application Notes

N-CHANNEL JFET, VOLTAGE CONTROLLED RESISTOR < Back LS26VNS N-CHANNEL JFET, VOLTAGE CONTROLLED RESISTOR The LS26VNS N-Channel Single JFET voltage controlled resistor has a drain-source resistance that is controlled by a DC bias voltage (VGS) applied to a high impedance gate terminal. Minimum RDS of 14 Ω occurs when VGS = -1.0V. As VGS approaches the pinch-off voltage of -6.0V RDS rapidly increases to the maximum value or RDS = 38 Ω. For the P-Channel version, please see our LS26VPS. Both the N and P-channel parts are made from the same die geometry, making them complimentary. This part is available in the TO-92 3L RoHS, SOT-23 3L RoHS and DFN 8L 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: LS26VNS TO-92 3L RoHS LS26VNS SOT-23 3L RoHS LS26VNS DFN 8L RoHS Datasheet Spice Model Application Notes

< Back Largest Digital Camera Linear Systems Mar 17, 2023 Engineering the World’s Largest Digital Camera Largest Digital Camera Big Science Project using Linear Systems' JFETs Advances SLAC's Large Scale Synoptic Telescope uses 2,000 Linear Systems LSK489 JFETs! The Large Scale Synoptic Telescope (LSST), which uses 2,000 Linear Systems LSK489 JFETs in its front-end amplification stage, is assembling what will be the world's largest camera when completed. This article describes the part of the project that includes our semiconductors: https://www.symmetrymagazine.org/article/engineering-the-worlds-largest-digital-camera Engineering the world’s largest digital camera | symmetry magazine www.symmetrymagazine.org A game of ‘Operation’ “When you consider a project this complex, you can’t just dive in and say ‘Here, I’m going to design and build this in one shot,’ right?” says Tim Bond, head of the LSST Camera Integration and Test team at SLAC.

< 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 .

HIGH INPUT IMPENDANCE, SINGLE, BIFET AMPLIFIER < Back LS320 HIGH INPUT IMPENDANCE, SINGLE, BIFET AMPLIFIER The LS320 Single, high Input Impedance, BIFET Amplifier is a direct replacement for Amperex equivalent part. It is ideal for High Impedance Sensor Amplifier Applications. Available in the TO-72 4L RoHS, TO-92 3L RoHS and SOT-23 3L 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: LS320 TO-72 4L RoHS LS20 TO-92 3L RoHS LS320 SOT-23 3L RoHS LS320 DIE Datasheet Spice Model Application Notes

P-CHANNEL JFET, VOLTAGE CONTROLLED RESISTOR < Back LS26VPS_ P-CHANNEL JFET, VOLTAGE CONTROLLED RESISTOR The LS26VPS is a P-Channel Single JFET voltage-controlled resistor. It has a drain-source resistance that is controlled by a DC bias voltage (VGS) applied to a high impedance gate terminal. Minimum RDS of 20 Ω occurs when VGS = 3.0V. As VGS approaches the pinch-off voltage of 7.5V, RDS rapidly increases to the maximum value or RDS = 50 Ω. For the N-Channel version, please see our LS26VNS. Both the N and P-channel parts are made from the same die geometry, making them complimentary. This part is available in the TO-92 3L RoHS, SOT-23 3L RoHS and DFN 8L 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: LS26VPS TO-92 3L RoHS LS26VPS SOT-23 3L RoHS LS26VPS DFN 8L RoHS Datasheet Spice Model Application Notes

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 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. Request a Quote 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. View Products High-Performance Components for Demanding Applications At Linear Systems, we specialize in precision analog components engineered for exceptional performance in the most demanding industries. Our flagship LSK series of ultra-low-noise JFETs—including the LSK389 and LSK170—delivers industry-leading noise performance trusted in critical applications worldwide. These monolithic dual and single N-Channel JFETs provide outstanding performance at competitive prices, complemented by a wide range of high-performance Improved Standard JFETs. For high-speed switching, our lateral DMOS switches set the standard for speed and reliability. Available as single and quad nanosecond switches with or without protection diodes, they enable fast, precise switching in demanding applications. Our PAD/JPAD/SSTPAD ultra-low-leakage diodes protect sensitive circuit inputs with leakage currents as low as -1 pA (PAD1). They’re ideal for op-amps, ADC analog inputs, analog multiplexers, and RS485 line receivers. The SST500 series of current-regulating diodes ensures consistent performance in high-reliability environments, such as test equipment, medical devices, and instrumentation. Using 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 Explore our: Current Regulating Diodes Explore our: High-Speed DMOS Switches

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. Contact Us: How can we assist you? Please select your request:* First name* Last name* Company name* Email* Phone number How did you hear about us?* Yes, subscribe me to your newsletter. For sample requests please complete the following: What does your company do / manufacture? Is this request for a new design or an existing design? What is the end application? Estimated annual usage (EAU) When is production expected to begin? To receive samples, please supply your FedEx, UPS, DHL, or other shipping account number Provide details about your request: Submit How to Reach Us: Address 4042 Clipper Court Fremont, CA 94538 Phone & Email (510) 490-9160 support@linearsystems.com Hours of Operation Mon - Fri 8:00 am – 5:00 pm Sat - Sun Closed