NXP Semiconductors BF904,215

Overview

BF904,215 from NXP Semiconductors is an N-channel dual-gate MOSFET in SOT143B package, designed for low-noise VHF/UHF amplifier stages operating at 5 V supply. It delivers 25 mS forward transfer admittance, 2.2 pF input capacitance at gate 1, and 2 dB noise figure at 800 MHz - enabling high-gain, low-distortion signal amplification in TV tuners and professional RF receivers.

For engineers reviewing the BF904,215 datasheet, BF904,215 pinout, BF904,215 application, or BF904,215 equivalent, key selection criteria include its dual-gate AGC capability, cross-modulation performance under gain control, thermal resistance (500 K/W), and compatibility with 3–7 V supply systems in broadcast and communications front-ends.

Technical Context

The BF904,215 integrates two cascaded MOSFET gates: gate 1 serves as RF input with low input capacitance (2.2 pF typ.) and high y_fs (25 mS typ.), while gate 2 functions as AGC-controlled bias node, enabling stable gain reduction without distortion. Its internal source-substrate connection ensures consistent channel behavior across temperature.

This device operates in enhancement mode with gate threshold voltages of 0.3–1.0 V (G1-S) and 0.3–1.2 V (G2-S), supports 30 mA max drain current, and maintains ≤2.8 dB noise figure up to 800 MHz - making it suitable for narrowband, high-selectivity RF amplifier designs requiring precise gain control.

Key Specifications

Pinout & Package

BF904,215 is housed in a plastic surface-mount SOT143B package (3.0 × 1.4 × 1.1 mm), optimized for RF layout with short lead lengths and defined ground path via source terminal.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BF998,215 and NE3210M04, the BF904,215 uniquely balances low-noise performance, built-in dual-gate AGC control, and proven VHF/UHF linearity - making it irreplaceable in legacy tuner architectures where cross-modulation immunity and 5 V compatibility are mandatory.

Availability

BF904,215 is available at Aetrix Electronics and suitable for television tuner front-ends, professional UHF receivers, and wireless microphone systems requiring stable component supply across long-lifecycle industrial and broadcast equipment programs.

Supply support for BF904,215 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 specializing in secure connectivity solutions for automotive, industrial, and consumer applications, with deep heritage in RF and analog component design.

The BF904,215 belongs to NXP's legacy RF transistor portfolio developed specifically for high-fidelity, low-noise amplification in broadcast and communications equipment - emphasizing AGC stability, cross-modulation immunity, and 5 V system compatibility.

FAQ

What is the maximum operating frequency supported by the BF904,215?

The BF904,215 is characterized for low-noise amplification up to 1 GHz, with verified performance including 2 dB noise figure at 800 MHz and usable forward transfer admittance (|y_{fs 1.7) up to 1 GHz, making BF904,215 appropriate for VHF, UHF, and lower L-band applications but not for 2.4 GHz or higher bands.}

How does the BF904,215 implement automatic gain control (AGC)?

The BF904,215 uses gate 2 (g2) as a dedicated AGC control terminal: applying 0–4 V to g2 modulates transconductance while maintaining input match at gate 1. This internal dual-gate structure eliminates external components needed for gain control, and BF904,215 achieves >40 dB gain reduction with <1% cross-modulation distortion - a key advantage over single-gate alternatives.

Is the BF904,215 pin-compatible with the BF904R variant?

No - BF904,215 uses SOT143B package with standard pinning (1=s,b, 2=d, 3=g2, 4=g1), whereas BF904R uses SOT143R with reversed pinning (1=s,b, 2=d, 3=g1, 4=g2). PCB layouts for BF904,215 are not interchangeable with BF904R; using BF904R in a BF904,215 design would invert gate connections and cause functional failure.

What thermal derating applies to the BF904,215 at elevated ambient temperatures?

BF904,215 has a total power dissipation limit of 200 mW at T_amb ≤ 50 °C. Above this, power must be linearly derated at 4 mW/°C (based on R_{th j-a} = 500 K/W). At 70 °C ambient, maximum allowable P_tot drops to 120 mW. Exceeding these limits risks junction temperature exceeding 150 °C and permanent device degradation.

Can the BF904,215 be used with a 3.3 V supply instead of 5 V?

Yes - BF904,215 is specified for 3–7 V supply operation. At 3.3 V, drain current reduces (e.g., IDSX drops from 8–13 mA to ~4–7 mA), forward transfer admittance decreases (~18–22 mS), and noise figure increases slightly (~2.3–2.6 dB at 800 MHz). BF904,215 remains functional but trade-offs in gain and noise must be validated per application.