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< 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

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

MONOLITHIC DUAL, NPN TRANSISTOR < Back IT120 Series MONOLITHIC DUAL, NPN TRANSISTOR Previous Next

SINGLE, LOW CAPACITANCE, ULTRA-HIGH INPUT IMPEDANCE N-CHANNEL JFET AMPLIFIER - DFN < Back 4117DFN SERIES SINGLE, LOW CAPACITANCE, ULTRA-HIGH INPUT IMPEDANCE N-CHANNEL JFET AMPLIFIER - DFN The 2N/PN/SST4117 Series Single, Low Capacitance, Ultra-High Input Impedance, N-Channel JFET Amplifier is a direct replacement for the Fairchild, NXP and Siliconix-Vishay equivalent part series. It is ideal for high input impedance applications. This series is available in the DFN 8L RoHS miniature/non/magnetic package, as well as the TO-72 4L RoHS, TO-92 3L RoHS, SOT-23 3L RoHS package and 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: 2N4117 TO-72 4L RoHS 2N4118 TO-72 4L RoHS 2N4119 TO-72 4L RoHS PN4117 TO-92 3L RoHS PN4118 TO-92 3L RoHS PN4119 TO-92 3L RoHS SST4117 SOT-23 3L RoHS SST4118 SOT-23 3L RoHS SST4119 SOT-23 3L RoHS 2N4117 Die 2N4118 Die 2N4119 Die Datasheet Spice Model Application Notes

MONOLITHIC DUAL, PNP TRANSISTOR < Back IT130 Series MONOLITHIC DUAL, PNP TRANSISTOR Previous Next

< 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

SINGLE, ULTRA-LOW NOISE, P-CHANNEL JFET AMPLIFIER < Back LSJ/SST74 Series SINGLE, ULTRA-LOW NOISE, P-CHANNEL JFET AMPLIFIER The LSJ/SST74 Single, Ultra-Low noise, P-Channel JFET Amplifier is a direct replacement for the Toshiba 2SJ74. It is ideal for Ultra-Low Noise Audio/Acoustic Applications. Available in the TO-92 3L RoHS, SOT-89 3L RoHS, 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: LSJ74A TO-92 3L RoHS LSJ74B TO-92 3L RoHS LSJ74C TO-92 3L RoHS LSJ74D TO-92 3L RoHS SST74A SOT-23 3L RoHS SST74B SOT-23 3L RoHS SST74C SOT-23 3L RoHS SST74D SOT-23 3L RoHS 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/U401 Series LOW-NOISE, LOW-DRIFT, MONOLITHIC DUAL N-CHANNEL JFET AMPLIFIER The SST/U401, 402, 403, 404, 405 and 406 Low-Noise, Low-Drift, Monolithic Dual N-Channel JFET amplifiers are targeted for use in a wide range of precision instrumentation and sensor applications. They are available in the TO-71 6L, SOIC 8L and SOT-23 6L 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: U401 TO-71 6L RoHS U402 TO-71 6L RoHS U403 TO-71 6L RoHS U404 TO-71 6L RoHS U405 TO-71 6L RoHS U406 TO-71 6L RoHS SST401 SOIC 8L RoHS SST402 SOIC 8L RoHS SST403 SOIC 8L RoHS SST404 SOIC 8L RoHS SST405 SOIC 8L RoHS SST406 SOIC 8L RoHS U401 Die U402 Die U403 Die U404 Die U405 Die U406 Die Datasheet Spice Model Application Notes

< Back FETching Discrete Amplifier Introduction Low-noise amplifiers for photodiode, piezoelectric, and other instrumentation applications typically call for circuit parameters such as extremely high input impedance, low 1/f noise, or subpicoamp bias currents that cannot be met with available integrated products. This article discusses the requirements and challenges of designing a low-noise amplifier using discrete components, with particular emphasis on input-referred noise and offset voltage trimming. Read More

MONOLITHIC-DUEL, P-CHANNEL ENHANCEMENT MODE MOSFET < Back 3N190 Series MONOLITHIC-DUEL, P-CHANNEL ENHANCEMENT MODE MOSFET The 3N190 Series Monolithic-Duel, P-Channel Enhancement Mode MOSFET is a direct replacement for Intersil and Siliconix-Vishay equivalent part. It is ideal for Amplifier and Switching Applications. This part series is available in TO-78 7L 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: 3N190 TO-78 7L RoHS 3N191 TO-78 7L RoHS Datasheet Spice Model Application Notes

< Back DMOS Product Line Linear Systems Mar 17, 2023 DMOS Product Line Acquired from Vishay/Siliconix DMOS Product Line Linear Systems Re-Launches DMOS Product Line Acquired from Siliconix FREMONT, CA - 04/02/2020 Linear Systems announces the re-release of the SD-Series lateral DMOS switch product line acquired from Vishay/Siliconix in 2001. Built using the industry-leading proprietary DMOS process developed by Siliconix and transferred to Linear Systems, the SD-series uses lateral construction to achieve low capacitance and ultra-fast switching speeds (1ns max). “Our lateral DMOS products continue the tradition established by Siliconix with its design and production of these devices,” Mr. Tim McCune said. “The DMOS parts we produce meet every specification established by Vishay/Siliconix when they made them. The customers who relied on Siliconix for these parts transitioned smoothly to using ours, and we’ve welcomed many new customers since then.” These lateral DMOS switches are key components in a variety of high-performance analog circuits where ultra-fast, nano-second switching times are critical. Linear Systems is the only company to build these lateral DMOS parts using Siliconix’ proprietary polysilicon gate technology and is the only Vishay/Siliconix-approved replacement manufacturer. This fabrication process is key to the unique combination of speed and reliability of these parts. Linear Systems in 2001 reached an agreement with Vishay/Siliconix to produce these lateral DMOS parts after Vishay decided to exit that business. Under that agreement, LIS received mask sets, and process and technical information for the SD210, SD214, SST211, SST213, SST215, SD5000, SD5001, SD5400, and SD5401 product families from Siliconix. These parts are available in thru-hole, surface mount, die, ROHS, and Non-ROHS(Lead) for medical and military applications. Special testing is also available. “This line of lateral DMOS has been critical to a large number of high-end product developers, and it was important to Vishay that these customers not be forced to design these parts out, or use inferior ones,” McCune said. McCune noted Linear Systems’ lateral DMOS parts are used in a wide variety of military applications that require Non-ROHS parts as well as civilian applications. “The key performance parameters – switching time, low capacitance– are important in all applications,” he said. This product line is supported by an in-depth application note, detailed data sheets and recently developed SPICE models in the LTspice® format. For the application note, please visit: http://www.linearsystems.com/lsdata/others/DMOSAnalogSwitchIntroduction.pdf . For data sheets and SPICE models, please visit: http://www.linearsystems.com/product.html?category=dmoshss . Linear Systems is a full-service, privately-held, 32-year-old 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 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

< 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