NXP Semiconductors BF1109WR,115

Overview

BF1109WR from NXP Semiconductors is an enhancement-type N-channel dual-gate MOSFET designed for VHF/UHF RF amplification in 9 V supply systems. It features 30 mS forward transfer admittance, 2.2–2.7 pF input capacitance at gate 1, 1.5–2.5 dB noise figure at 800 MHz, and integrated gate-source protection diodes. It serves as a low-noise gain-controlled amplifier in television tuners and professional communications receivers.

For engineers reviewing the BF1109WR datasheet, BF1109WR pinout, BF1109WR application, or BF1109WR equivalent, key selection criteria include its self-biasing drain current (8–16 mA), cross-modulation performance (100 dBµV at 40 dB AGC), thermal resistance (350 K/W), and SOT343R package compatibility with high-frequency layout requirements.

Technical Context

The BF1109WR operates as a common-source RF amplifier with internal self-biasing circuitry that stabilizes DC operating point under AGC conditions and improves cross-modulation performance. Its dual-gate structure enables independent control of RF signal injection (gate 1) and gain setting (gate 2), with gate 2-source threshold voltage specified between 0.3 V and 1.2 V.

It exhibits pulsed forward transfer admittance of 24–30 mS, reverse transfer capacitance of 25–40 fF, and power gain of 20 dB at 800 MHz under matched source/load conditions (GS = 3.3 mS, GL = 1 mS). The device is rated for 11 V drain-source breakdown and 150 °C maximum junction temperature.

Key Specifications

Pinout & Package

SOT343R plastic surface-mounted package (4 leads, reverse pinning); dimensions: 2.2 × 1.35 × 0.9 mm (L × W × H); lead pitch 0.5 mm; moisture sensitivity level not specified.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BF1109WR, the BF1109R and BF1109 share identical RF parameters and bias behavior but differ in package outline and pin numbering - BF1109WR's SOT343R offers smaller footprint (2.2 × 1.35 mm) and reversed pin order (1=drain, 2=source, 4=gate2, 3=gate1), enabling higher-density RF board layouts.

Availability

BF1109WR is available at Aetrix Electronics and suitable for television tuner front-ends, professional UHF receivers, and RF test equipment requiring stable component supply, long-lifecycle support, and verified RF performance consistency.

Supply support for BF1109WR 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 company specializing in high-performance RF, analog, and mixed-signal solutions for communications, automotive, and industrial markets.

The BF1109WR belongs to NXP's legacy RF transistor product line, engineered specifically for low-noise, high-gain amplification in VHF/UHF consumer and professional broadcast and communications equipment.

FAQ

What is the maximum operating junction temperature for the BF1109WR?

The BF1109WR has a maximum operating junction temperature of +150 °C, as defined in its limiting values table. This rating applies under conditions where total power dissipation does not exceed 200 mW at ambient temperatures ≤80 °C. Thermal derating is required above 80 °C ambient, with R_{th j-a} = 350 K/W specifying the thermal resistance from junction to ambient in free air. Designers must verify PCB copper area and airflow to maintain safe T_j in final applications.

Does the BF1109WR require external bias components for basic operation?

No, the BF1109WR incorporates an internal self-biasing circuit that establishes a stable 8–16 mA drain current when V_G2-S = 4 V and V_DS = 9 V. This eliminates the need for external source resistors or bias networks in many tuner applications. Gate 1 remains high-impedance for RF input, while gate 2 can be driven directly by an AGC voltage or fixed bias, reducing bill-of-materials count and board space.

What is the pin configuration of the BF1109WR in its SOT343R package?

The BF1109WR uses reverse pinning in the SOT343R package: Pin 1 = Drain, Pin 2 = Source, Pin 4 = Gate 2, Pin 3 = Gate 1 (top view). This differs from the standard SOT143B/SOT143R pinout (1=Source, 2=Drain, 3=Gate 2, 4=Gate 1). Layouts must account for this reversal to avoid functional failure; the marking code "NB" on the device body confirms SOT343R packaging.

How does the BF1109WR achieve low noise performance at 800 MHz?

The BF1109WR achieves a typical noise figure of 1.5–2.5 dB at 800 MHz through its short-channel enhancement-mode structure, optimized gate geometry, and internal self-biasing that stabilizes operating point under varying signal conditions. Its low 25–40 fF reverse transfer capacitance minimizes feedback-induced noise, while the 2.2–2.7 pF input capacitance at gate 1 enables precise input matching to 50 Ω sources - all contributing to repeatable low-noise amplification in UHF front-ends.

Can the BF1109WR replace the BF1109 or BF1109R without circuit modification?

No - although the BF1109WR shares identical electrical specifications with the BF1109 and BF1109R, its SOT343R package has reversed pin numbering (1=Drain, 2=Source, 4=Gate 2, 3=Gate 1) versus the standard pinout of the other variants. Direct replacement would cause incorrect connections unless the PCB layout is revised. Electrical substitution is valid only after verifying pin mapping and adjusting routing; thermal and RF performance remain fully equivalent post-layout update.