This part is a kind of semiconductor called 2N5566.

Function of this product has Matched N-Channel JFET Pairs.

Manufacturers : Vishay Siliconix

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Some of the text within the PDF file :

2N5564/5565/5566 Vishay Siliconix Matched N-Channel JFET Pairs PRODUCT SUMMARY Part Number 2N5564 2N5565 2N5566 VGS(off) (V) –0.5 to –3 –0.5 to –3 –0.5 to –3 V(BR)GSS Min (V) –40 –40 –40 gfs Min (mS) 7.5 7.5 7.5 IG Typ (pA) –3 –3 –3 jVGS1 – VGS2j Max (mV) 5 10 20 FEATURES D D D D D D D Two-Chip Design High Slew Rate Low Offset/Drift Voltage Low Gate Leakage: 3 pA Low Noise: 12 nV⁄√Hz @ 10 Hz Good CMRR: 76 dB Minimum Parasitics BENEFITS D Tight Differential Match vs. Current D Improved Op Amp Speed, Settling Time Accuracy D Minimum Input Error/Trimming Requirement D Insignificant Signal Loss/Error Voltage D High System Sensitivity D Minimum Error with Large Input Signals D Maximum High Frequency Performance APPLICATIONS D Wideband Differential Amps D [ ... ]

2N5566 PDF Datasheet Download