BF1211,215

Overview

The BF1211,215 is an N-channel dual-gate MOS-FET designed for low-noise amplification in VHF and UHF applications. It features a short channel transistor with high forward transfer admittance to input capacitance ratio, ensuring excellent low-frequency noise performance. The device includes partly internal self-biasing circuitry to maintain good cross-modulation performance during automatic gain control (AGC) and provides DC stabilization. Integrated diodes between gates and source protect against excessive input voltage surges. It operates with a drain-source voltage of up to 6V and a drain current of 30mA, packaged in SOT143B plastic surface-mounted packages.

Feature Summary

• Dual-gate enhancement type N-channel field-effect transistor with integrated gate-to-source protection diodes.
• Internal self-biasing circuit ensures stable DC operation and minimizes cross-modulation distortion during AGC adjustments.
• Optimized for low-noise amplification with high forward transfer admittance relative to input capacitance.
• Designed for effective signal processing in digital and analog television tuner environments.

Applications

• Gain controlled low noise VHF amplifiers
• Gain controlled low noise UHF amplifiers
• 5 V digital television tuner applications
• 5 V analog television tuner applications

Procurement Notes

Verify the specific package variant required, as the BF1211 family includes distinct pinning configurations. The BF1211 uses standard SOT143B pinout, while BF1211R and BF1211WR utilize reverse pinning in SOT143R and SOT343R packages respectively. Confirm that the ordering suffix matches the intended PCB footprint and pin assignment to prevent installation errors. Ensure electrostatic discharge precautions are observed during handling due to the sensitivity of the MOSFET structure.

Selection Notes

Select this component when designing amplifiers requiring precise gain control via a second gate terminal. The dual-gate architecture allows independent biasing for optimal noise figure and linearity trade-offs. Consider the thermal resistance characteristics when determining heat dissipation requirements, particularly regarding the junction-to-soldering point thermal resistance. Verify that the operating frequency range aligns with the device's specified forward transfer admittance and noise figure performance curves for the target application bandwidth.

Part Context

This component belongs to the discrete semiconductor category, specifically within NXP's portfolio of RF and analog transistors. It serves as a fundamental building block for front-end radio frequency circuits where signal integrity and low noise are critical. The dual-gate configuration distinguishes it from single-gate MOSFETs by providing an additional control port for gain modulation without significantly impacting the input impedance characteristics of the primary signal path.

Replacement Considerations

BF1211R: Plastic surface mounted package; reverse pinning; 4 leads [SOT143R]. BF1211WR: Plastic surface mounted package; reverse pinning; 4 leads [SOT343R].