U441

Overview

The Vishay Siliconix U441 is a matched pair of N-channel JFETs housed in a hermetically sealed TO-71 package. It features a two-chip design that minimizes parasitics for high-frequency performance. Key electrical parameters include a gate-source cutoff voltage (VGS(off)) ranging from -1 V to -6 V, a minimum forward transconductance (gfs) of 4.5 mS, and a maximum differential gate-source voltage matching of 20 mV. The device supports an operating junction temperature range of -55°C to +150°C with a total power dissipation of 500 mW.

Feature Summary

• Two-chip monolithic design reduces parasitics and ensures tight matching between the paired JFETs.
• Hermetically sealed TO-71 package suitable for demanding environments and military screening.
• Low gate leakage current of 1 pA typical, contributing to low noise and high input impedance.
• High common-mode rejection ratio (CMRR) of 85 dB for effective signal processing.

Applications

• Wideband differential amplifiers
• High-speed comparators
• Impedance converters

Procurement Notes

Verify the specific lot code and revision status against the latest datasheet revision D (04-Jun-01). Confirm that the TO-71 package availability aligns with current manufacturing capabilities, as older packages may have limited supply chains. Ensure environmental compliance requirements are met if the application demands RoHS or REACH adherence beyond standard specifications.

Selection Notes

Select the U441 when precise matching between two N-channel JFETs is required without external trimming. The 20 mV maximum differential VGS(off) makes it superior to general-purpose discrete JFETs for precision analog circuits. Consider the TO-71 package constraints regarding board space and thermal management compared to modern surface-mount alternatives like the SST441.

Part Context

The U441 belongs to a family of matched JFET pairs designed for high-performance analog applications. It serves as a direct replacement for legacy siliconix components in test and measurement equipment. The companion part U440 offers similar characteristics but with a tighter 10 mV matching specification for VGS(off), catering to even higher precision requirements.

Replacement Considerations

For surface-mount replacements, consider the SST441 in SO-8 packaging. For lower noise options, evaluate the SST/U401 series. If lower leakage is critical, review the U421/423 data sheets. Verify pinout compatibility when transitioning from the TO-71 package to alternative form factors.

FAQ

What is the maximum differential gate-source voltage matching for the U441?

The maximum differential gate-source voltage (|VGS1 – VGS2|) for the U441 is specified at 20 mV under test conditions of VDG = 10 V and ID = 5 mA.

Is the U441 suitable for military applications?

Yes, the hermetically sealed TO-71 package is available with full military screening per MIL-S-19500.

How does the U441 differ from the U440?

The primary difference lies in the matching specification; the U441 allows a maximum differential VGS(off) of 20 mV, whereas the U440 has a stricter limit of 10 mV.