NXP Semiconductors BF1205,115

Overview

BF1205 from NXP Semiconductors is a dual N-channel dual-gate MOSFET in SOT363 package, integrating two low-noise amplifiers with shared source and gate-2 leads plus an internal AGC-controlled switch. It delivers 31 mS forward transfer admittance, 1.2–1.4 dB noise figure at 800 MHz, and >98 dBµV cross-modulation rejection at 40 dB AGC, enabling VHF/UHF gain-controlled LNA stages in 5 V TV tuners and professional comms equipment.

For engineers reviewing the BF1205 datasheet, BF1205 pinout, BF1205 application, or BF1205 equivalent, key selection criteria include dual-gate noise performance at UHF, integrated switching for AGC path control, gate-1 bias-dependent amplifier enable/disable behavior, and SOT363 footprint compatibility with high-density RF front-end layouts.

Technical Context

The BF1205 implements two matched dual-gate MOSFETs (Amplifier A and B) sharing source (Pin 5) and gate-2 (Pin 2), with independent gate-1 inputs (Pins 1 and 3). Amplifier B's gate-1 (Pin 3) controls the internal switch that enables/disables Amplifier A - VGG = 0 V activates Amp A while deactivating Amp B, and VGG = 5 V reverses this state per Fig.4.

Each amplifier operates in common-source configuration with fully or partly integrated DC bias networks. Integrated protection diodes clamp gate-to-source surges, and substrate-source interconnection ensures stable RF grounding. Thermal resistance is 240 K/W junction-to-soldering-point, with 200 mW total power dissipation derated above Ts = 102 °C.

Key Specifications

Pinout & Package

Encapsulated in SOT363 - a 6-lead micro-miniature plastic surface-mount package (2.2 × 1.35 × 1.15 mm) with gull-wing leads, optimized for RF layout and reflow compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BF1204,115, the BF1205 adds integrated switching for automatic path selection, reducing component count and layout complexity. Against MRF9011LT1G, it trades some NF and frequency headroom for built-in dual-gate AGC functionality essential in tuner architectures.

Availability

BF1205 is available at Aetrix Electronics and suitable for analog/digital TV tuners, professional UHF wireless receivers, and land mobile radio front-ends requiring stable component supply, consistent RF performance, and long-term obsolescence management.

Supply support for BF1205 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 automotive, industrial, and consumer applications.

The BF1205 belongs to NXP's legacy RF transistor portfolio designed specifically for VHF/UHF gain-controlled low-noise amplification in broadcast and professional communications equipment.

FAQ

What is the maximum drain-source voltage rating for the BF1205?

The BF1205 has a maximum drain-source voltage (V_DS) rating of 10 V per MOSFET, as specified in the Absolute Maximum Ratings table. This rating applies independently to both Amplifier A and Amplifier B, allowing safe operation with standard 5 V supply rails while accommodating transient overvoltage conditions typical in RF front-end environments. Exceeding 10 V risks permanent device damage.

How does the internal switch in the BF1205 operate between the two amplifiers?

The internal switch in the BF1205 is controlled by the gate-1 voltage of Amplifier B (Pin 3, labeled VGG). When VGG = 0 V, Amplifier A is enabled and Amplifier B is disabled; when VGG = 5 V, Amplifier B is enabled and Amplifier A is disabled. This complementary switching behavior is defined in Fig.4 and enables seamless AGC-driven path selection without external control circuitry - a core functional distinction of the BF1205 versus single-amplifier dual-gate MOSFETs like the BF1204,115.

What is the typical noise figure of the BF1205 at 800 MHz?

The BF1205 achieves a typical noise figure (NF) of 1.2 dB for Amplifier A and 1.4 dB for Amplifier B at 800 MHz, measured under standard conditions (V_DS = 5 V, V_G2-S = 4 V, I_D = 12 mA). These values are confirmed in the Dynamic Characteristics sections for each amplifier and reflect its suitability for demanding UHF reception applications such as digital terrestrial television tuners where sub-1.5 dB NF is critical for weak-signal performance.

Can the BF1205 be used with a 3.3 V supply instead of 5 V?

The BF1205 is characterized and optimized for 5 V operation, and its Quick Reference Data and Dynamic Characteristics assume V_DS = 5 V. While static parameters like V_(BR)DSS (min 7–10 V) suggest possible 3.3 V use, gain (G_tr), noise figure, and cross-modulation performance degrade significantly below 5 V due to reduced transconductance and altered bias points. NXP does not specify or guarantee performance at 3.3 V; therefore, BF1205 should be operated at 5 V for full compliance with published specifications.

What package type is the BF1205 supplied in, and what are its key mechanical dimensions?

The BF1205 is supplied in the SOT363 plastic surface-mounted package - also known as SC-88 - with 6 gull-wing leads. Its nominal dimensions are 2.2 mm × 1.35 mm × 1.15 mm (L × W × H), lead pitch of 0.65 mm, and thermal resistance R_{th j-s} = 240 K/W. The package outline conforms to JEDEC MO-203 and IEC 60191 standards, and the marking code "L4-" appears on the top surface for traceability.