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< Back Military Sensor Signal Chains Introduction Higher-performance sensors are becoming increasingly important to modern battlefield systems. Sensors ranging from sonobuoys to radiation detectors are critical, leading-edge components of C4ISR systems. Better sensor systems enable earlier threat detection and more effective countermeasures. Military systems employ a wide range of sensors – nuclear, biological, and chemical sensing, infrared, electro-optical, laser, radar, and acoustical – that all have one aspect in common: the requirement for ultra-low-noise signal chains to produce the best possible sensor signal. Less-than-optimal front-end amplification means C4ISR clients receive inadequate information and are not able to make effective, real-time decisions. This paper describes techniques to employ to create the lowest-noise, most effect front-end amplification for sensor signal chains. Advanced lithography design and fab process techniques enable the creation of discrete components uniquely capable of performing the critical initial amplification of sensor signals. Integrated circuits contain a wide range of components and can include specialized design features that preclude design optimization for low noise. As this paper documents, ultra-low-noise discrete components added to an IC-based circuit will produce the lowest-noise signal chain. Though this paper focuses on the LSK489 dual monolithic Nchannel JFET, many other Linear Systems parts -- including the LSK389, LSK170 and LSK189 -- also are excellent sensor system components. Linear Systems is the world leader in ultra-low-noise monolithic dual JFETs and other front-end discrete components key to high-performance sensing systems. For over three decades, Linear Systems has led the development of this class of devices, and it continues to advance their design and introduce new sensor-specific parts. Read More

< Back Low Leakage Diodes Introduction In circuit designs for sensor signal conditioning, the design engineer must protect the input section from over current and over voltage conditions. Op amps, ADC analog inputs, analog multiplexers, and [RS485] line receivers represent classes of devices that need protection. Often, the manufacturers of such devices specify the acceptable input range for voltage, or, in the case of an overvoltage condition, the allowable input current above which semiconductor or bonding wires may be damaged. Read More

< 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

GENERAL PURPOSE < Back LS190 GENERAL PURPOSE The LS190 is a General Purpose Single N-Channel JFET Amplifier. This part is available in the TO-92 3L package, as well as the SOT-89 3L package. 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. Datasheet Spice Model Application Notes

< Back Interfacing Sensors & Transducers Introduction Abstract: A discussion of methods of amplifying and signal-conditioning for sensors with low level outputs in the presence of high ambient electrical noise sources. Advantages and disadvantages of some common amplifier circuits are considered. Read More

< 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

< Back LS26VPS/VNS Press Release Linear Systems Mar 17, 2023 New JFET Voltage-Controlled Resistors NEWS RELEASE FOR INFORMATION CONTACT: Linear Systems, Inc. Sales Department Phone: (510) 490-9160 Email: sales@linearsystems.com Build lower-voltage, lower-power circuits using Linear Systems' industry-leading voltage-controlled resistors. Linear Systems has expanded its family of JFET Voltage-Controlled Resistors (VCRs) for reduced-power circuits over IC-based devices. Two new additions to the JFET Voltage-Controlled Resistor Family include the LS26VNS, a Single N-Channel JFET VCR, and the LS26VPS, a Single P-Channel JFET VCR. Both the N and P-channel versions are made from the same die geometry, making them complementary. They join the existing VCR11N, a Dual N-Channel VCR. The advantages of using VCRs for voltage-controlled amplifier or voltage-controlled gain systems include: - VCR-based devices operate with lower voltage and power consumption, enabling battery-powered systems to last significantly longer. - VCR JFETs can be used with low-power op amps to provide a low-power solution for voltage-controlled gain systems. - With low voltage op amps such as the LMV358 or TLC272, VCR JFETs perform voltage-controlled gain at extremely low supply voltages, down to a single 3.3V power supply. Circuits can be designed for very low power consumption when combined with low voltage, low power op amps. For instance, using an LSK389A as a VCR for these low voltage circuits can provide significant efficiency gains. - Matched pair JFET VCRs (VCR11N or LSK389A) can provide two identical channels of voltage-controlled gain, where the control voltage tracks both channels. This can be used in stereo audio signal attenuation. In contrast, typical active voltage-controlled amplifiers drain more current and require higher minimum power supply voltages, needing at least +/- 4 volts for a specialized voltage control amplifier integrated circuit. P-Channel JFETs, including a J177, can be designed as a VCR circuit with a single power supply. For example, the P-Channel JFET VCR circuit is ideal with positive supply voltages since its control voltage to the gate is also positive. Product Details: - LS26VNS N-Channel Single JFET VCR: Drain-source resistance 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 of 38 Ω. - LS26VPS P-Channel Single JFET VCR: Drain-source resistance 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 of 50 Ω. Summary of Features : - LS26VNS (N-Channel Single) - RDS(on) 14-38 Ω - BVgss 30 Volts - Available in TO-92 3L, SOT-23 3L, DFN 8L, and Bare Die options - LS26VPS (P-Channel Single) - RDS(on) 20-50 Ω - BVgss 30 Volts - Available in TO-92 3L, SOT-23 3L, DFN 8L, and Bare Die options Applications: - Variable Gain Controls - Voltage Controlled Oscillators - Signal Attenuators - Musical Effects Applications - Adaptive Analog Filters - Automatic Gain Control Circuits - Clock Generators - Compressors - Electrometers - Energy Harvesters - Expanders - Hearing Aids - Light Dimmers - Modulators - Mixers - Artificial Neural Networks - Programmable Gain Amplifiers - Phased Arrays - Phase Lock Loops - Phase Controlled Dimming Circuits - Phase Delay and Advance Circuits - Tunable Filters - Variable Attenuators - Voltage Controlled Multivibrators - Waveform Generators Pricing and Availability: - 1,000+ pieces of the LS26VNS and LS26VPS in the TO-92 3L, SOT-23 3L, and DFN 8L packages are priced at $1.23 (USD) each. - Production quantities are available now with delivery from factory stock to 8 weeks. This product line is supported by application notes, datasheets, and SPICE models. For further technical resources, please click HERE . 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 found at www.linearsystems.com. For more information, contact Linear Systems at (510) 490-9160 or email sales@linearsystems.com. https://www.linearsystems.com/voltagecontrolledresistors/ls26vps

Linear Systems designs and manufactures the highest-performance line of monolithic dual JFETs in the industry. Contact us for a quote! Back 2N5564 Series LOW NOISE, MONOLITHIC DUAL, N-CHANNEL JFET The 2N5564 Series is a Low Noise, Monolithic Dual, N-Channel JFET. These matched pairs of JFETs are mounted in a TO-71 package. The two-chip design reduces parasitics for good performance at high frequency while ensuring extremely tight matching. This series features high breakdown voltage, high gain, and <5 mV offset between the two die. It is a Pin-for-Pin Replacement for Siliconix-Vishay 2N5564 Series, available in the TO-71 6L 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: 2N5564 TO-71 6L RoHS 2N5565 TO-71 6L RoHS 2N5566 TO-71 6L RoHS 2N5564 Die 2N5565 Die 2N5566 Die Datasheet Spice Model Application Notes

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

SINGLE, LOW-NOISE, LOW-LEAKAGE, N-CHANNEL JFET AMPLIFIERS < Back LSK189 SINGLE, LOW-NOISE, LOW-LEAKAGE, N-CHANNEL JFET AMPLIFIERS The LSK189 Single, Low Noise, Low Leakage, N-Channel JFET Amplifiers is a single version of LSK489 Series. It is ideal for Ultra Low Noise Audio/Acoustic Applications. Available in TO-92 3L ROoHS, 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: LSK189 TO-92 3L RoHS LSK189 SOT-23 3L RoHS LSK189 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 LS830 Series ULTRA-LOW LEAKAGE, LOW DRIFT, MONOLITHIC DUAL N-CHANNEL JFET The LS830 Series of Ultra-Low Leakage, Low Drift, Monolithic Dual N-Channel JFETs 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: LS830 TO-71 6L RoHS LS831 TO-71 6L RoHS LS832 TO-71 6L RoHS LS833 TO-71 6L RoHS LS830 TO-78 6L RoHS LS831 TO-78 6L RoHS LS832 TO-78 6L RoHS LS833 TO-78 6L RoHS LS830 PDIP 8L RoHS LS831 PDIP 8L RoHS LS832 PDIP 8L RoHS LS833 PDIP 8L RoHS LS830 SOIC 8L RoHS LS831 SOIC 8L RoHS LS832 SOIC 8L RoHS LS833 SOIC 8L RoHS LS831 Die LS832 Die LS833 Die Datasheet Spice Model Application Notes