BF1105WR,115

Overview

The BF1105WR,115 is an enhancement type N-channel dual-gate MOS-FET encapsulated in the SOT343R plastic package. It features a short channel transistor with high forward transfer admittance to input capacitance ratio and an internal self-biasing circuit for DC stabilization. Key electrical parameters include a drain-source voltage of 7 V, a maximum drain current of 30 mA, and total power dissipation of 200 mW at temperatures up to 80 °C. The device exhibits a typical forward transfer admittance of 31 mS and operates with a junction temperature range up to 150 °C.

Feature Summary

• Dual-gate architecture with integrated self-biasing circuitry for improved cross-modulation performance during automatic gain control.
• Internal diodes between gates and source provide protection against excessive input voltage surges.
• Optimized for low noise amplification applications operating up to 1 GHz.

Applications

• VHF and UHF television tuners
• Professional communications equipment
• Low noise gain controlled amplifier circuits

Procurement Notes

Verify the specific ordering suffix

Selection Notes

Select this component for designs requiring a compact surface-mount RF transistor with dual-gate isolation capabilities. The SOT343R package suits space-constrained PCB layouts. Ensure the application operates within the 7 V drain-source voltage limit and 30 mA current constraints. Consider the thermal resistance characteristics when designing heat dissipation strategies for continuous operation near the maximum ambient temperature rating.

Part Context

This part belongs to the BF1105 series of N-channel dual-gate MOS-FETs manufactured by NXP Semiconductors. The series includes variants such as the BF1105 (SOT143B) and BF1105R (SOT143R), which share identical electrical specifications but differ in physical packaging. The BF1105WR specifically utilizes the smaller SOT343R outline, maintaining compatibility with the functional requirements of VHF/UHF tuner stages while offering a reduced footprint compared to standard surface-mount packages.

Replacement Considerations

Direct replacements must match the SOT343R package and dual-gate N-channel MOSFET configuration. Verify that substitute components meet the 7 V drain-source voltage and 30 mA drain current limits. Cross-reference pinouts carefully, as reverse pinning configurations exist within the family.

FAQ

What is the function of the second gate?

Gate 2 serves as the control terminal for automatic gain control (AGC) and biasing, allowing the device to function as a low noise gain-controlled amplifier.

How does the device handle input voltage surges?

Integrated diodes are connected between the gates and the source to protect the transistor against excessive input voltage surges.

What is the maximum operating junction temperature?

The maximum operating junction temperature is 150 °C.