The U401/ LSU401 is a Low Noise, Low Drift, Monolithic Dual N-Channel JFET

The LSU401 is a high-performance monolithic dual JFET featuring extremely low noise, tight offset voltage and low drift over temperature specifications, and is targeted for use in a wide range of precision instrumentation applications. The LSU401 features a 5-mV offset and 10-µV/°C drift. The LSU401 is a direct replacement for discontinued Siliconix U401.
The hermetically sealed TO-71 & TO-78 packages are well suited for military applications

FEATURES
  LOW DRIFT        |V GS1-2 / T| = 10µV/°C TYP.
  LOW NOISE        en = 6nV/Hz @ 10Hz TYP.
  LOW PINCHOFF     Vp = 2.5V TYP.
 
U401 / LSU401 Applications:
■ Wideband Differential Amps
■ High-Speed,Temp-Compensated Single Ended Input Amps
■ High-Speed Comparators
■ Impedance Converters and vibrations detectors.