NXP Semiconductors BF908R,215

Overview

BF908R,215 from NXP Semiconductors is a depletion-mode dual-gate MOSFET in SOT143R package, designed for low-noise RF amplification up to 1 GHz. It delivers forward transfer admittance of 43 mS (typ), input capacitance at gate 1 of 3.1 pF (typ), and noise figure of 1.5 dB (typ) at 800 MHz - optimized for VHF/UHF tuner front-ends operating at 12 V supply.

For engineers reviewing the BF908R,215 datasheet, BF908R,215 pinout, BF908R,215 application, or BF908R,215 equivalent, key selection criteria include its dual-gate architecture for gain control and AGC integration, low-noise performance at UHF frequencies, thermal derating behavior (550 K/W junction-to-ambient), and gate protection via integrated back-to-back diodes.

Technical Context

The BF908R,215 implements a short-channel dual-gate structure with independent gate control: Gate 1 (g1) serves as signal input with cut-off voltage ≤ −2 V, while Gate 2 (g2) acts as bias/control terminal with cut-off voltage ≤ −1.5 V. Its high y_fs/C_ig1-s ratio (13.9 mS/pF typ) enables stable gain across 50–1000 MHz.

Dynamic operation is specified under common-source configuration at V_DS = 8 V, V_G2-S = 4 V, I_D = 15 mA. Scattering parameters confirm broadband gain (|s₂₁| > 3.8 @ 100 MHz, > 2.5 @ 1 GHz) and low reverse isolation (|s₁₂| < 0.005 up to 1 GHz), supporting cascade amplifier design without neutralization.

Key Specifications

Pinout & Package

SOT143R plastic microminiature package (3.0 × 1.4 × 0.95 mm), surface-mount, lead-free compatible. Pin 1: source (s,b); Pin 2: drain (d); Pin 3: gate 2 (g2); Pin 4: gate 1 (g1). Integrated back-to-back diodes between each gate and source provide surge protection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BF908R,215, BF998,215 offers higher gain and bandwidth at identical footprint, while NE3210M04 trades dual-gate convenience and built-in protection for ultra-low noise - demanding more complex biasing and layout validation.

Availability

BF908R,215 is available at Aetrix Electronics and suitable for television tuners, professional UHF receivers, and VHF communications equipment requiring stable component supply and long-term obsolescence management.

Supply support for BF908R,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 company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and consumer applications.

The BF908R,215 belongs to NXP's legacy RF transistor portfolio, engineered specifically for high-performance, low-noise amplification in VHF/UHF receiver front-ends where dual-gate control and integrated ESD protection are essential.

FAQ

What is the maximum operating junction temperature for BF908R,215?

The BF908R,215 has a maximum operating junction temperature of 150 °C, as defined in its limiting values table. This specification ensures reliable operation under transient thermal loads in compact tuner modules. Derating begins at 40 °C ambient due to its 550 K/W thermal resistance, meaning sustained full-power operation requires careful thermal management in enclosed environments. The BF908R,215 must not exceed this junction limit to avoid permanent degradation of forward transfer admittance or gate oxide integrity.

Does BF908R,215 require external ESD protection?

No, the BF908R,215 integrates back-to-back diodes between each gate and source, providing inherent protection against input voltage surges. This design eliminates the need for external ESD protection components in most 12 V supply applications like TV tuners. However, handling precautions remain critical: the device ships in antistatic packaging, and gate-source terminals must be protected from static discharge during PCB assembly. The BF908R,215's ±20 V gate-source breakdown voltage further supports robustness in typical RF front-end environments.

How does BF908R,215 differ from BF908,215?

The BF908R,215 uses the SOT143R package variant with modified leadframe geometry (0.38 mm lead width vs. 0.60 mm in SOT143), resulting in higher thermal resistance (550 K/W vs. 500 K/W) and derating starting at 40 °C ambient instead of 50 °C. Both share identical electrical specifications, pinout order, and marking code (%M2). The BF908R,215 was introduced to improve manufacturability and consistency in automated assembly, while maintaining full functional equivalence with BF908,215 in RF amplifier circuits.

Can BF908R,215 be used in 5 V supply applications?

The BF908R,215 is characterized and optimized for 12 V supply systems, with absolute maximum V_DS rated at 12 V and typical performance data (e.g., noise figure, y_fs) specified at V_DS = 8 V. While it may operate at lower drain voltages, gain and noise performance degrade significantly below 5 V - for example, |y_fs| drops ~30% at V_DS = 3 V. The BF908R,215 is not recommended for 5 V-only designs; alternative low-voltage RF transistors with appropriate characterization should be selected instead.

What is the typical noise figure of BF908R,215 at 200 MHz?

The BF908R,215 achieves a typical noise figure of 0.6 dB at 200 MHz under optimal matching conditions (G_S = G_Sopt, B_S = B_Sopt), as documented in its dynamic characteristics table. This value reflects its capability as a high-sensitivity front-end device in VHF applications such as aircraft band receivers. The noise figure rises to 1.5 dB at 800 MHz, confirming its broadband low-noise behavior across the entire VHF/UHF range. All noise data for BF908R,215 assumes common-source configuration with V_DS = 8 V, V_G2-S = 4 V, and I_D = 15 mA.