< Back CMR Ratio in Dual JFETs Introduction When choosing the optimal JFET for a new circuit, a characteristic often overlooked is how the part’s design affects the rejection of unwanted inputs while amplifying the signal as accurately as possible. Single JFETs provide excellent impedance matching and low-noise amplification, but lack one important quality of their dual counterparts – dual discrete devices largely reject common signals. This important characteristic – Common Mode Rejection – means that selecting the right dual JFET can be the most cost-effective way of improving signal-to-noise ratio in a design. Read More

< 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.

MONOLITHIC DUAL AND SINGLE, PNP TRANSISTOR < Back LS3550 Series MONOLITHIC DUAL AND SINGLE, PNP TRANSISTOR The LS3550 Monolithic Dual and Single, PNP Transistor is a Higher Current Version of the MP350, MP351, and MP352 Series. 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: LS3550A TO-71 6L RoHS LS3550B TO-71 6L RoHS LS3550C TO-71 6L RoHS LS3550A TO-78 6L RoHS LS3550B TO-78 6L RoHS LS3550C TO-78 6L RoHS LS3550A PDIP 8L RoHS LS3550B PDIP 8L RoHS LS3550C PDIP 8L RoHS LS3550A SOIC 8L RoHS LS3550B SOIC 8L RoHS LS3550C SOIC 8L RoHS LS3550A Die LS3550B Die LS3550C 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 .

LOG CONFORMANCE, MONOLITHIC DUAL, NPN TRANSISTOR < Back LS318 LOG CONFORMANCE, MONOLITHIC DUAL, NPN TRANSISTOR The LS318 Log Conformance, Monolithic Dual, NPN Transistor is a direct replacement for the Micro Power Systems MP318 Series. It is ideal for Log Conformance, Transistors 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: LS318 TO-71 6L RoHS LS318 TO-78 6L RoHS LS318 PDIP 8L RoHS LS318 SOIC 8L RoHS LS318 Die Datasheet Spice Model Application Notes

LS3250 Single NPN High-Speed Switching Transistor < Back LS3250S - Single LS3250 Single NPN High-Speed Switching Transistor Previous Next

Discover our diverse product line of innovative solutions at 4042 Clipper Court, Fremont, CA, USA. From Ultra-Low-Noise JFETs to Current Regulating Diodes, DMOS High-Speed Switches, MOSFETs, Bipolar Transistors, Low Leakage Diodes, and Voltage Controlled Resistors, we offer cutting-edge technology to meet your needs. Find the perfect solution for your requirements today! Our Products Explore our portfolio of precision analog semiconductors. Below you'll find our product families, each designed to deliver exceptional performance in demanding analog applications. Request a Quote Request Samples Contact an Engineer Dual JFETs Ultra-low-noise matched monolithic JFETs for precision analog circuits requiring exceptional noise performance, thermal tracking, and device matching. Single JFETs High-performance single JFETs designed for low-noise amplification, high input impedance, and precision analog signal processing. JFET Switches Precision JFET analog switches offering excellent linearity, low distortion, and reliable switching for demanding analog designs. DMOS Switches High-speed lateral DMOS switches with nanosecond switching speeds, extremely low crosstalk, and exceptional isolation for precision analog switching applications. Low Leakage Diodes Ultra-low reverse leakage diodes with leakage currents as low as 1 pA, ideal for electrometers, photodiodes, and precision measurement systems. Current Regulating Diodes Precision current-regulating diodes (CRDs) providing stable constant-current sources over a wide operating voltage range. Bipolar Transistors Low-noise bipolar transistors available in single and monolithic dual configurations for precision analog and instrumentation applications. MOSFETs Precision MOSFETs designed for analog switching, signal conditioning, and specialized low-power applications. VCRs Voltage Controlled Resistors that provide precise, voltage-variable resistance for automatic gain control, filtering, and analog signal processing. BIFET Amplifier Low-noise BiFET operational amplifiers combining JFET inputs with bipolar output stages for high input impedance and precision analog performance. Sample Box Evaluate our precision analog semiconductors with convenient sample kits featuring a selection of our most popular devices.

Linear Systems typically doesn't require visitors to provide personal information for website use. However, in certain cases, we may ask for it to facilitate future communications, purchases, or material requests. We reserve the right to collect and share personal information in response to violations, fraud, or actions that may harm our company, but otherwise, we do not share your information with third parties. Privacy Policy Collection of Personal Information Visitors to the Linear Integrated Systems' website are not required to reveal any personal information in order to use many of the features of the site. However, in some instances, Linear Systems requests that users provide certain personal information in order to facilitate future communications, make a purchase of Linear Systems' products, or receive other materials from Linear Systems. What does Linear Systems do with my personal information? Linear Systems will use the information you provide for legitimate business purposes which may include sharing some information with Linear Systems' authorized distributors. These legitimate business purposes may include facilitating future communications with you, assisting you in making a purchase of Linear Systems' products, or responding to your request for Linear Systems' information or samples. Linear Systems also reserves the right to collect and share personal information as part of an investigation or response to a violation of Linear Systems' terms and conditions, fraud, illegal activities or other actions or threats which may damage Linear Systems. Except the aforementioned instances, Linear Systems will never share your personal information with third parties. Rev. A 03202023 Home

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. How can we assist you? Please complete the form below and we will contact you promptly. 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

Explore our services and get in touch Our Services 01. Custom Project This service involves collaborating closely with you to define the scope, objectives, and deliverables for a unique project tailored to your specific needs. We will support you from initial concept through to detailed planning, ensuring all aspects are covered. This ensures a clear roadmap for successful execution. Show more 02. Personal Solution Planning We offer dedicated one-on-one sessions to understand your individual challenges and goals. Through active listening and guided discussion, we help you map out a personalized strategy for achieving your desired outcomes. Our aim is to provide clear, actionable steps for your personal journey. Show more 03. Expert Guidance Package Gain insights and strategic direction from industry professionals dedicated to your success. This package includes focused sessions designed to explore potential solutions and identify optimal paths forward for your business or personal goals. We equip you with the knowledge to make informed decisions. Show more

< Back Testing Capability Linear Systems Mar 17, 2023 New Low-Noise Semiconductor Testing Capability FREMONT, Calif., April 11, 2019 /PRNewswire/ -- Linear Integrated Systems, Inc. (Linear Systems) will be unveiling its large-scale sub-nanovolt parts testing capability at the 23rd Annual Conference and Exhibition for Components for Military & Space Electronics (CMSE) in Los Angeles. This testing capability enables individual screening of small-signal discrete components to levels below a billionth of a volt (nV/√Hz) of noise in quantities up to tens of thousands of parts. Linear Systems created this capability in response to a U.S. defense program requirement and is now providing ultra-low-noise-screened parts to other customers. "Small-signal discrete components can help create the lowest noise signal chains possible and that's what our customers have been demanding," said Timothy S. McCune. "This sub-nanovolt testing capability enables us to provide production-line quantities of parts guaranteed to meet specific noise levels. No other company has this capability." Linear Systems will be available to discuss this capability and its line of precision small-signal discrete components at the 23rd Annual Conference and Exhibition for Components for Military & Space Electronics (CMSE) to be held at the Four Points by Sheraton (LAX), Los Angeles on April 16-18. CMSE is the premier event focused on the design, reliability, and application of electronic components for use in avionics aerospace, military & commercial space systems. The conference provides access to more than 30 technical presentations by industry leaders, focused on advanced packaging of ICs, passive components, and a number of other topics critical to components used in high reliability military and aerospace systems. Linear Systems specializes in the development and manufacture of precision, ultra-low-noise small-signal discrete components. Its parts, such as the LSK389 and LSK489, are used in highly demanding sensor systems ranging from the Large-Scale Synoptic Telescope to piezoelectric devices to sonobuoys. These parts also provide the front-end amplification for high-end test and measurement, medical and audio equipment. Linear Systems is a full-service, privately-held, designer and manufacturer of small-signal discrete semiconductors established in 1987. The Fremont, CA-based company was founded by John H. Hall, co-founder of Intersil and founder of Micro Power Systems. Linear Systems' 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. Data sheets, applications notes, SPICE models and other information can be downloaded at linearsystems.com . For more information about Linear Systems please contact Ms. Laura Madonna at laura@linearsystems.com . For customer service, please contact Linear Systems at sales@linearsystems.com or call (510) 490-9160. SOURCE Linear Integrated Systems Related Links www.linearsystems.com

< Back LSK489 App Note Introduction For circuits designed to work with high impedance sources, ranging from electrometers to microphone preamplifiers, the use of a low-noise, high-impedance device between the input and the op amp is needed in order to optimize performance. At first glance, one of Linear Systems’ most popular parts, the LSK389 ultra-low-noise dual JFET would appear to be a good choice for such an application. The part’s high input impedance (1 TΩ) and low noise (1 nV/√Hz at 1kHz and 2mA drain current) enables power transfer while adding almost no noise to the signal. But further examination of the LSK389’s specification shows an input capacitance of over 20pF. This will cause intermodulation distortion as the circuit’s input signal increases in frequency if the source impedance is high. This is because the JFET junction capacitances are nonlinear. This will be especially the case where common source amplifier arrangements allow the Miller effect to multiply the effective value of the gate-drain capacitance. Further, the LSK389’s input impedance will fall to a lower value as the frequency increases relative to a part with lower input capacitance. A better design choice is Linear Systems’ new offering, the LSK489. Though the LSK489 has slightly higher noise (1.5 nV/√Hz vs. 1.0 nV/√Hz) its much lower input capacitance of only 4pF means that it will maintain its high input impedance as the frequency of the input signal rises. More importantly, using the lower-capacitance LSK489 will create a circuit that is much less susceptible to intermodulation distortion than one using the LSK389. The LSK489’s lower gate-to-drain capacitance enables more effective, elegant audio circuit designs. The relatively high capacitance of the LSK389 often requires designers to use a cascode circuit to provide the ability to handle higher bandwidths without intermodulation distortion. The cascode does this by eliminating the Miller effect that can multiply the effective gate-drain capacitance and its associated nonlinear effects. However, the cascode adds complexity and noise contributed by the cascode transistors. The LSK489 is an N-channel dual low-noise, low-capacitance, tightly matched monolithic field effect transistor. It features: • 3ms transconductance at 2mA drain current • 1000 GΩ input impedance • 60V breakdown voltage • gate-drain capacitance of only 1.5pF • 4pF input capacitance • 1.5 nV/√Hz noise at 1kHz • best low-noise/low-capacitance combination in the industry • lowest input capacitance per unit gate length in the industry • lowest noise for a given gate length in the industry • tight Vgs matching at operating bias Read More