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LSJ689 Application Note
LINEAR INTEGRATED SYSTEMS ANNOUNCES ULTRA LOW NOISE P-CHANNEL DUAL JFET
FREMONT, CALIFORNIA - June 1, 2016 - Linear Integrated Systems (LIS), a leading full-service manufacturer of specialty linear semiconductors, announces the immediate availability of its LSJ689, a 1.8 nV/Hz @ 1kHz, low-capacitance, monolithic dual P-Channel JFET. The LSJ689 is a P-Channel complement to our monolithic dual N-Channel JFET, the LSK489. This latest addition to the LIS family of Ultra-Low-Noise JFETs provides users with many more design options than available by using only N-Channel JFETs. Additionally, the monolithic dual construction of the LSJ689 and LSK489 provides better solutions for obtaining tighter Idss (drain-source saturation current) matching and improved thermal tracking than matching individual JFETs.
Historically, P-Channel JFETs availability has declined. Complementary Single N-Channel and P-Channel JFETs have become limited to a few industry standards. Complementary monolithic dual N-Channel and P-Channel JFETs have not been offered for many years, leaving designers under supported. In response, LIS produced Single Complementary N & P Channel JFETs, the LSK170 and LSJ74 family. The LSJ689 and LSK489 provide additional options for designers. The LSJ689/LSK489 have 1/5 the capacitance of the LSK170 and LSJ74, 4pF versus 25pF. A unique Monolithic Dual design construction of interweaving each JFET on the same piece of silicon provide excellent matching and thermal tracking.
When used together, the LSJ689 and LSK489 are ideal for differential input stages for amplifier, phono, and preamplifier designs. Additional applications for the LSJ689 include voltage controlled resistors, thermal stable source followers, sample and hold, and current matched sources.
The LSJ689 is an ideal improved functional replacement for JFETs that have similar noise characteristics with reduced gate-to-drain capacitance. It is available in RoHS compliant SOT-23 6L, SOIC-A 8L and TO-71 6L package options. The LSJ689 SOT-23 6L and SOIC-A 8L packages are ideal for space-limited circuits in audio and instrumentation applications.
Summary of Features:
- Complement to the Ultra Low Noise Monolithic Dual N-Channel JFET LSK489
- Ultra Low noise (typically 1.8 nV/Hz @ 1kHz)
- Nearly zero popcorn noise
- Idss (drain-source saturation current) matching to 10% max
- Low offset/tight matching (|Vgs1- Vgs2| = 20mV max)
- Low capacitance (Ciss=4 pF)
- High input impedance
- High breakdown voltage (BVGSS = 40V Min)
- Monolithic Dual (2 JFETS on one piece of silicon, better matching and thermal tracking)
- Surface mount SOIC-A 8L versions and the smaller SOT-23 6L package
- Lead-free/ROHS compliant
Microphone amplifiers, phono preamplifiers, audio amplifiers and preamps, discrete low-noise operational amplifiers, battery-operated audio preamps, audio mixer consoles, acoustic sensors, sonic imaging, and instrumentation amplifiers, wideband differential amplifiers, high speed comparators, impedance converters, voltage controlled resistors, sample and hold, source followers.
Availability: Sampling now in SOIC-A 8L, TO-71 6L and SOT-23 6L
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