< Back Solving the Noise Puzzle Introduction Noise is one of the more important aspects of circuit design. Lower noise in audio amplifier design means better quality audio. Low-noise in instrument design means more reliable and accurate measurements at lower voltage and current levels. And low-noise in current source designs means less noise injected into the electronic system. One of the most basic approaches to reduce noise in an amplifier is to use low-noise components. This would include low-noise bipolar transistors and low-valued resistors. Although one can use low-noise operational amplifiers in the design of low-noise circuits or low-noise current sources it is often not done. This is because lower noise can be often be obtained with a well-thought out discrete design. And that’s because discrete transistors offer much more design customization capability for specific circuit applications – like optimized collector biasing. One must remember that monolithic chip designs are built for the most part for general purpose applications. It is hard to tailor a specific op amp or current source chip for a specific source resistance, specific power consumption requirement and a specific bandwidth that will lower the overall noise – that is unless you add-on more compensation components. Read More

Linear Systems designs and manufactures the highest-performance line of monolithic dual JFETs in the industry. Contact us for a quote! Back LS840 Series LOW-NOISE, LOW-DRIFT, LOW CAPACITANCE, MONOLITHIC DUAL N-CHANNEL JFET AMPLIFIER The LS840 Series Low-Noise, Low-Drift, Low-Capacitance, Monolithic Dual N-Channel JFET Amplifier is a pin-for-pin replacement for the Fairchild, Motorola, National and Siliconix-Vishay part series. Available in the TO-71 6L, TO-78 6L, PDIP 8L 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: LS840 TO-71 6L RoHS LS841 TO-71 6L RoHS LS842 TO-71 6L RoHS LS840 TO-78 6L RoHS LS841 TO-78 6L RoHS LS842 TO-78 6L RoHS LS840 PDIP 8L RoHS LS841 PDIP 8L RoHS LS842 PDIP 8L RoHS LS840 SOIC 8L RoHS LS841 SOIC 8L RoHS LS842 SOIC 8L RoHS LS840 Die LS841 Die LS842 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

Linear Systems designs and manufactures the highest-performance line of monolithic dual JFETs in the industry. Contact us for a quote! Back SST/U421 Series LOW LEAKAGE, LOW DRIFT, MONOLITHIC DUAL, N-CHANNEL JFET The SST/U421 Series Low-Noise, Low-Drift, Monolithic Dual N-Channel JFET Amplifier is designed for a broad spectrum of precision instrumentation and sensor applications. This series is offered in TO-71 6L, TO-78 7L, PDIP 8L, and SOIC 8L RoHS-compliant packages, 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 The following options are available for ordering this part series: U421 TO-71 6L RoHS U422 TO-71 6L RoHS U423 TO-71 6L RoHS U424 TO-71 6L RoHS U425 TO-71 6L RoHS U426 TO-71 6L RoHS U421 TO-78 7L RoHS U422 TO-78 7L RoHS U423 TO-78 7L RoHS U424 TO-78 7L RoHS U425 TO-78 7L RoHS U426 TO-78 7L RoHS SST421 SOIC 8L RoHS SST422 SOIC 8L RoHS SST423 SOIC 8L RoHS SST424 SOIC 8L RoHS SST425 SOIC 8L RoHS SST426 SOIC 8L RoHS U421 Die U422 Die U423 Die U424 Die U425 Die U426 Die Datasheet Spice Model Application Notes

< Back LS844 App Note Introduction 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 T) 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 gatedrain 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’ LS844. Though the LS844 has slightly higher noise (2.5 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 LS844 will create a circuit that is much less susceptible to intermodulation distortion than one using the LSK389. The LS844’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 LS844 is an N-channel dual low-noise, lowcapacitance, tightly matched monolithic field effect transistor. It features: • 3ms transconductance at 2mA drain current • 1000 G input impedance • 60V breakdown voltage • gate-drain capacitance of only 1.5pF • 4pF input capacitance • 2.5 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 The LS844 is particularly well suited to low-noise, highgain audio and instrumentation circuits operating from battery voltages up to 60 volts. 48V phantom-powered circuits, like those used in microphone preamplifiers, are especially benefited by the features of the LS844. Low operating Vgs, high gm, tight matching, low noise and low capacitance make it well-suited to numerous audio and instrumentation applications. Sensors, which play such an important role in today’s world, benefit greatly from the performance delivered by the LS844. Such sensor technologies include piezo, quartz, condenser, electret, and MEMs devices. These devices benefit from the LS844’s combination of low input capacitance and low noise. Electrometer applications also benefit from these characteristics. Read More

< Back Millions of Devices in Stock! Linear Systems Mar 17, 2023 LS844 Monolithic Dual Small-Signal JFET, 3N163 Small-Signal MOSFET, LS320 BiFET and Many More! NEWS RELEASE FOR INFORMATION CONTACT: Linear Systems, Inc. Sales Department Phone: (510) 490-9160 Email: sales@linearsystems.com Linear Systems Announces Large-Scale Availability of Ultra Low Noise JFETs and Small-Signal Semiconductors FREMONT, Calif. – August 26, 2021 – Linear Systems, a world-class producer of ultra-low-noise JFETs and other small-signal discrete semiconductors, announces the large-scale availability of five of its top-performing components. These components, ranging from low-noise monolithic dual JFETs to small-signal MOSFETs, are available in wafer form in quantities ranging from one million to ten million for immediate packaging and shipment. All parts meet Linear Systems' industry-leading datasheet specifications and are available for fast delivery due to substantial buffer stock of wafers. Parts available for shipment include : 1. LS844 Monolithic Dual Small-Signal JFET: One million dice in wafer form in stock. This low-noise front-end amplifier features high Common Mode Rejection Ratio and excellent matching over a wide range of temperatures. [Download Data Sheet] 2. 3N163 Small-Signal MOSFET : Three million dice in wafer form in stock. Ideal for sensor applications such as gas detection and piezo devices, with half the noise of competitors' parts. [Download Data Sheet] 3. LS320 BiFET Amplifier: 1.3 million dice in wafer form in stock. A high-input impedance, single monolithic amplifier, designed as a direct replacement for Amperex equivalent parts. Perfect for high impedance sense amplifier applications. [Download Data Sheet] 4. 2N/PN/SST4391 N-Channel JFET Series: 2.5 million dice in wafer form in stock. This single, low-noise N-channel JFET switch is ideal for low-noise, high-gain, low-resistance switching and amplifier applications. [Download Data Sheet] 5. 2N/PN/SST4117A N-Channel JFET Series: 14.3 million dice in wafer form in stock. This single, low-capacitance, ultra-high-input-impedance N-channel JFET amplifier is a direct replacement for Fairchild, NXP, and Siliconix-Vishay parts. [Download Data Sheet] These parts are also available in bare die and sorted wafer form. In addition to these million-plus parts inventories, Linear Systems keeps substantial quantities of all its parts on hand, including the industry-leading LSK389 monolithic dual N-channel ultra-low-noise JFET. About Linear Systems Founded in 1987, Linear Systems is a Silicon Valley-based designer, manufacturer, and seller of precision, high-performance, small-signal discrete semiconductors. Linear Systems produces ultra-low-noise monolithic dual and single JFETs, bipolar transistors, high-speed DMOS switches, small-signal MOSFETs, ultra-low-leakage diodes, and BiFET amplifiers. These parts are designed into world-class products in fields such as Test & Measurement, Audio, Scientific Optical, Military Sensor, Hydrophone/Sonobuoys, Industrial Controls, and Hybrids. For these and other parts, download Linear Systems' [Product Selection Guide] and [Databook]. For more information, visit www.linearsystems.com .

< Back SD5400/SD5000 Linear Systems Mar 17, 2023 Introducing Family of Quad N-channels NEWS RELEASE FOR INFORMATION CONTACT: Linear Systems, Inc. Sales Department Phone: (510) 490-9160 Email: sales@linearsystems.com Linear Systems Announces the Immediate Availability of SD5400 / SD5000 Family of Quad N-Channel Enhancement Mode Lateral DMOS Analog Switches FREMONT, CA – Linear Systems is announcing the immediate availability of the SD5400 / SD5000 Family of Quad N-Channel Enhancement Mode Lateral DMOS Analog Switches, specifically designed for high-speed switching applications. These ultra-fast switches offer improved accuracy, speed, and throughput, with less glitching or distortion than JFETs or multiplexers. Designed for high-frequency RF operation, they provide switching speeds of 1ns with a unique combination of 70 ohms "ON" resistance and a reverse transfer capacitance of 0.5 pF. A maximum threshold of 1.5 volts permits simple TTL and CMOS driving for small signal applications. The SD5400 / SD5000 can switch analog signals up to +/- 10 volts, while the SD5401 / SD5001 can switch signals up to +/- 5 volts. All versions include gate ESD protection with zener diodes. The surface mount versions, SD5400 / SD5401, are available in 14 and 16 pin narrow body SOIC packages. The thru-hole versions, SD5000N / SD5001N, are available in 16 pin DIP packages. All package types are available with special electrical selection, including bare die form. Summary of Features : - High Speed Switching (td (ON) / (OFF) = 1ns max) - Ultra Low Reverse Capacitance (Crss = 0.5 pF max) - Low Turn-On Threshold Voltage (Vgs(th) = 1.5V max) - Switches Analog Signals up to +/- 10 volts - CMOS and TTL Compatible - Second Source Replacement for Calogic and Siliconix SD5400 / SD5000 Families - Available in Surface Mount SOIC-14, 16 pin, PDIP-16 Packages, and Bare Die Applications: - ATE (Automatic Test Equipment) Analog Switch - Analog to Digital and Digital to Analog Converters - Laser Drivers - Medical Imaging - Multiplexer - Sample and Hold - Switch Driver - Vision Systems Delivery: Factory Stock For more information, contact Linear Systems at sales@linearsystems.com or call (510) 490-9160. About Linear Systems Founded in 1987, Linear Systems is a full-service, privately-held designer and manufacturer of small-signal discrete semiconductors. 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 includes 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. Datasheets, application notes, SPICE models, and additional information can be downloaded at www.linearsystems.com.

< Back Jaime Cook: VP of Operations & Market Development Linear Systems Nov 21, 2024 Jaime Cook Appointed VP of Operations & Market Development at Linear Systems, Inc. Fremont, CA – October 1, 2024 – Linear Integrated Systems, Inc. is pleased to announce the appointment of Jaime L. Cook as Vice President of Operations and Market Development. In this pivotal role, Jaime will oversee all operational functions and spearhead market development initiatives. Jaime Cook has been a valued member of the Linear Systems team since 2009. Before stepping into her new role, Jaime served as Sales Manager, Director of Sales, and VP of Operations, gaining extensive experience across multiple facets of the company. Jaime brings a wealth of knowledge and expertise to her position as VP of Operations & Market Development. She holds bachelor's degrees in Real Estate and Land Use, as well as Strategic Management. Her education, certifications, and work experience have honed her skills in strategic planning, negotiation, and relationship building—qualities that significantly contribute to her expanded responsibilities at Linear Systems. “I’m incredibly proud to have built my career at Linear Systems and to be part of a team of exceptional individuals committed to producing the industry’s best specialty linear semiconductors while consistently meeting the highest standards of performance and reliability,” said Cook. “I am excited to expand my responsibilities, drive operational excellence, and lead efforts to explore new market opportunities.” Cindy L. Johnson, CEO of Linear Systems, stated, “Jaime’s leadership in operations and market development is pivotal as we aim to expand our product reach and strengthen customer relationships. Her strategic vision is vital to our mission of delivering ultra-reliable JFETs and other components that enable our clients to achieve outstanding performance in their designs.” Founded 37 years ago by John M. Hall, Cindy L. Johnson, and John H. Hall, Linear Integrated Systems, Inc. is a privately held designer and manufacturer of small-signal discrete semiconductors based in Fremont, CA. John H. Hall, a co-founder of Intersil and the founder of Micro Power Systems, brought significant expertise and innovation to the company. Linear Systems offers a diverse product line, including Dual JFET Amplifiers , Single JFET Amplifiers , JFET Switches , DMOS High Speed Switches , Low Leakage Diodes , Current Regulating Diodes , Bipolar Transistors , MOSFETs , Voltage Controlled Resistors and BIFET Amplifiers . Visit www.linearsystems.com to download our 2024 Data Book , Cross Reference Guide , datasheets, SPICE models, application notes , and more. Stay connected and join our growing LinkedIn community for updates and insights. You can also follow us on YouTube , Facebook , Instagram and X .

LOG CONFORMANCE, MONOLITHIC DUAL, PNP TRANSISTOR < Back LS358 LOG CONFORMANCE, MONOLITHIC DUAL, PNP TRANSISTOR The LS358 Log Conformance, Monolithic Dual, PNP Transistor is a direct replacement for Micro Power Systems MP358 Series. It is ideal for Log Conformance, 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 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: LS358 TO-71 6L RoHS LS358 TO-78 6L RoHS LS358 PDIP 8L RoHS LS358 SOIC 8L RoHS LS358 Die Datasheet Spice Model Application Notes

< Back JFETs for VC Circuits Introduction Linear Integrated Systems manufactures a variety of FETs (Field Effect Transistors). In particular they have a variety of matched dual products. There are advantages in having matched devices. For example, if you are building a twochannel stereo audio product, having two or four devices in the same package allows for the two audio channels to be more closely matched. This paper will explore using FETs in voltage controlled circuits. Several approaches will be shown: 1. Using FETs as voltage controlled resistors. 2. Using FETs as voltage controlled amplifiers and active mixers. 3. Using FETs as voltage controlled phase shifters for processing music. 4. Using FETs as voltage controlled band pass filters. We will also explore ways to reduce nonlinearities or distortions and automatically bias the FETs. Read More

SINGLE, HIGH FREQUENCY, N-CHANNEL JFET AMPLIFIER < Back 2N/PN/SST4416 Series SINGLE, HIGH FREQUENCY, N-CHANNEL JFET AMPLIFIER The 2N/PN/SST4416 Series Single, High Frequency, N-Channel JFET Amplifier is a direct replacement for the Fairchild, NXP, and Siliconix-Vishay equivalent part. It is ideal for High Frequency Applications. Available in the TO-72 4L, TO-92 3L and SOT-23 3L RoHS package, as well as 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: 2N4416 TO-72 4L RoHS 2N4416A TO-72 4L RoHS PN4416 TO-92 3L RoHS PN4416A TO-92 3L RoHS SST4416 SOT-23 3L RoHS SST4416A SOT-23 3L RoHS 2N4416 Die 2N4416A Die Datasheet Spice Model Application Notes

< Back LSJ689 App Note Introduction The dual monolithic P-channel LSJ689 is the complement to the N-channel LSK489. Both devices feature low offset, low noise and low capacitance. They enable the efficient implementation of fully complementary input stages without many of the device matching requirements when pairs of discrete devices are employed. Used alone, the LSJ689 also enables the implementation of more traditional differential input stages in applications where P-channel devices are preferred. Features of the LJ689 include: Low noise on the order of 2 nV/Hz Low gate-drain capacitance, typically 3pF Low gate leakage current typically 3pA (Vds = 15V, Id = 1mA) Breakdown voltage of 50V o IDSS range of 5-20 mA Typical transconductance of 3mS at Id = 1mA This note covers the full-complementary input stage application for the LSJ689 in combination with the LSK489. Read More