NXP Semiconductors BFG135,115

Overview

BFG135,115 from NXP Semiconductors is an NPN silicon planar epitaxial wideband RF transistor in SOT223 package, designed for high-frequency amplifier stages up to 7 GHz. It delivers 850 mV output voltage at 793.25 MHz under −60 dB distortion, achieves 7 GHz transition frequency at 100 mA/10 V, and supports 150 mA DC collector current with 1 W total power dissipation.

For engineers reviewing the BFG135,115 datasheet, BFG135,115 pinout, BFG135,115 application, or BFG135,115 equivalent, this device is selected for UHF/VHF broadband amplification where low intermodulation distortion, stable thermal profile, and high unilateral gain at 500–800 MHz are critical design requirements.

Technical Context

The BFG135,115 employs small emitter structures with integrated emitter-ballasting resistors to maintain low distortion while enabling high output voltage swing. Its active area distribution across the die surface ensures uniform thermal conduction through the collector tab, supporting reliable operation up to 145 °C soldering point temperature.

It operates as a common-emitter RF amplifier with measured S-parameters (S11, S21, S12, S22) characterized at 25 °C, 100 mA, and 10 V; maximum unilateral power gain reaches 16 dB at 500 MHz and remains ≥12 dB at 800 MHz, confirming suitability for multi-band UHF front-end designs.

Key Specifications

Pinout & Package

SOT223 plastic surface-mounted package with 4 leads and integrated heatsink tab (collector connection); dimensions per JEDEC SC-73 standard: 6.7 × 3.7 × 1.8 mm, with 2.3 mm lead pitch and 0.8 mm body thickness.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN wideband RF transistor applications.

Compared with BFG135,115, the BFG134,115 offers reduced high-frequency performance but identical mounting and biasing, while the MRF581 trades SOT223 integration for higher power handling in through-hole form - neither is pin-compatible, but both serve overlapping UHF amplifier roles with distinct thermal and layout trade-offs.

Availability

BFG135,115 is available at Aetrix Electronics and suitable for CATV infrastructure, broadcast auxiliary links, wireless microphone systems, and terrestrial TV tuner designs requiring stable component supply across extended production lifecycles.

Supply support for BFG135,115 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 BFG135,115 belongs to NXP's legacy wideband RF transistor product line, engineered specifically for linear UHF amplifier applications demanding low distortion, stable gain, and robust thermal behavior in compact surface-mount packages.

FAQ

What is the maximum operating frequency supported by the BFG135,115?

The BFG135,115 has a typical transition frequency (f_T) of 7 GHz, verified at IC = 100 mA and VCE = 10 V. This makes it suitable for amplifier designs operating up to 793.25 MHz with confirmed linearity and gain, and usable in narrowband applications approaching 1 GHz where gain compression and phase linearity remain within specification. The BFG135,115 is not rated for continuous operation beyond its characterized 7 GHz f_T limit.

Does the BFG135,115 require external emitter degeneration resistors?

No, the BFG135,115 integrates emitter-ballasting resistors directly into its silicon structure, eliminating the need for external degeneration components. This internal ballasting ensures stable DC bias and improved thermal uniformity across the dual-emitter configuration (Pins 1 and 3), which is confirmed in the device description and reflected in its low distortion performance at 850 mV output. External resistors would degrade RF performance and are not recommended for the BFG135,115.

How is thermal management implemented for the BFG135,115 in PCB layout?

The BFG135,115 uses Pin 4 (collector) as its primary thermal interface, with a specified R_{th j-s} of 30 K/W to the soldering point. Effective thermal management requires soldering Pin 4 to a minimum 100 mm² copper pour on the PCB's inner or outer layer, preferably with thermal vias to internal ground planes. The datasheet explicitly defines Ts as the temperature at the collector tab solder joint, and derating begins above 145 °C - proper copper area prevents exceeding this limit under 1 W dissipation.

Can the BFG135,115 be used in Class AB amplifier configurations?

The BFG135,115 is characterized and optimized for Class-A operation, with all key parameters (G_UM, d₂, V_O) specified at IC = 100 mA and VCE = 10 V - a fixed-bias Class-A condition. While it may function in Class AB, the device lacks published SOA curves or safe operating area data for dynamic switching conditions, and its emitter-ballasting is tuned for linear Class-A stability. For Class AB use, full characterization including thermal cycling and IMD validation would be required - the BFG135,115 datasheet does not support or guarantee such operation.

What is the significance of the dual-emitter terminals (Pins 1 and 3) on the BFG135,115?

Pins 1 and 3 are both connected to the same emitter region inside the BFG135,115 die - they are not independent emitters. This dual-terminal layout reduces series inductance in the emitter return path, improves high-frequency current distribution, and enhances thermal symmetry across the active area. It is a mechanical and electrical optimization specific to the SOT223 package, and both pins must be connected to the same net (typically AC ground) in the PCB layout to realize the full benefit described in the BFG135,115 datasheet.