NXP Semiconductors BF909,215

Overview

BF909,215 from NXP Semiconductors is an N-channel dual-gate MOSFET in SOT143 package, designed for low-noise RF amplification at 5 V supply. It delivers 43 mS typical forward transfer admittance, 2.0–2.8 dB noise figure at 800 MHz, and 4.3 pF input capacitance at gate 1 - optimized for VHF/UHF TV tuners and professional communications receivers.

For engineers reviewing the BF909,215 datasheet, BF909,215 pinout, BF909,215 application, or BF909,215 equivalent, key selection criteria include its dual-gate AGC capability, cross-modulation performance below −100 dBµV at 1% distortion, thermal resistance of 500 K/W (junction-to-ambient), and compatibility with 3–7 V supply rails in high-frequency front-end designs.

Technical Context

This enhancement-mode MOSFET integrates an internal bias circuit linking source and substrate to stabilize gain during automatic gain control (AGC). Gate 1 serves as RF input with 3.6–4.3 pF capacitance; Gate 2 acts as DC-controlled gain-setting terminal with 2.3–3.0 pF input capacitance and 0.3–1.2 V threshold voltage.

It operates up to 1 GHz with pulsed |y_fs| ≥36 mS, exhibits reverse transfer capacitance ≤50 fF at 1 MHz, and maintains 150 °C maximum junction temperature. Its 200 mW total power dissipation is derated linearly above 50 °C ambient for BF909 variants.

Key Specifications

Pinout & Package

BF909,215 is housed in a plastic microminiature SOT143 package (3.0 × 1.4 × 0.95 mm), surface-mount compatible with standard reflow profiles. The device features four terminals in a single-row configuration with gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-gate MOSFET amplifier applications.

Compared with BF909,215, BF998,215 offers extended frequency response and higher transconductance for broadband designs, while MRF901LT1G trades AGC capability and noise performance for higher output power and 3.3 V compatibility - making BF909,215 the optimal choice for low-noise, gain-controlled VHF/UHF amplification.

Availability

BF909,215 is available at Aetrix Electronics and suitable for television tuners, professional UHF receivers, FM radio IF amplifiers, and wireless microphone receivers requiring stable component supply and long-term obsolescence management.

Supply support for BF909,215 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

NXP Semiconductors is a global semiconductor leader headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and consumer applications.

The BF909,215 belongs to NXP's legacy RF transistor portfolio, engineered specifically for low-noise, dual-gate amplification in broadcast and professional communications equipment operating from 50 MHz to 1 GHz.

FAQ

What is the maximum operating frequency of the BF909,215?

The BF909,215 is characterized for low-noise amplification up to 1 GHz, with verified scattering parameters (S-parameters) and noise data published through 1000 MHz. Its forward transfer admittance remains usable beyond 1 GHz, but design margin and matching network losses typically limit practical use to ≤1 GHz in production VHF/UHF systems. The BF909,215 achieves 2.652 magnitude for S21 at 800 MHz, confirming robust gain retention in UHF bands.

Does the BF909,215 support automatic gain control (AGC) functionality?

Yes, the BF909,215 is explicitly designed for AGC operation: Gate 2 accepts a DC control voltage (typically 2–5 V) that adjusts transconductance without disturbing the RF signal path at Gate 1. Its internal source-substrate connection and bias circuit ensure stable cross-modulation performance during gain reduction - demonstrated by Fig.4 showing <−100 dBµV unwanted voltage at 1% distortion. This makes BF909,215 ideal for AGC loops in TV tuners and professional receivers.

What is the thermal resistance of the BF909,215 and how does it affect PCB layout?

The BF909,215 has a junction-to-ambient thermal resistance (R_{th j-a}) of 500 K/W when mounted on a standard PCB. This means a 100 mW dissipation raises junction temperature by 50 °C above ambient. To maintain T_j ≤150 °C at 50 °C ambient, keep power below 200 mW and provide ≥25 mm² of 1-oz copper connected to Pin 1 (source) as a thermal pad. The BF909,215 datasheet Fig.3 confirms derating begins at 50 °C ambient - so layout must prioritize source-side copper area and airflow.

Can the BF909,215 be used with a 3.3 V supply?

The BF909,215 is specified for 5 V operation (V_DS = 5 V, V_G2-S = 4 V) and performs optimally within its 3–7 V supply range. At 3.3 V, drain current drops significantly (see Fig.11), reducing |y_fs and increasing noise figure - measured F rises to ~3.5 dB at 800 MHz. While functional, 3.3 V operation sacrifices 0.5–1.0 dB NF and ~30% gain. For true 3.3 V designs, consider NXP's BF998,215 or alternatives explicitly rated for lower V_DS.

What is the ESD sensitivity level of the BF909,215 and how should it be handled?

The BF909,215 is supplied in antistatic packaging and has gate oxide vulnerable to ESD damage - the datasheet cautions that "the gate-source input must be protected against static discharge during transport or handling." Its absolute maximum gate current is ±10 mA, implying HBM ESD rating likely <2 kV. Always use grounded wrist straps, conductive foam, and ionized air when handling; include 100 Ω series resistors on Gate 1 traces and avoid floating gate nodes in PCB layout. Never apply voltage to Gate 1 before establishing source ground.