NXP Semiconductors BFG35,115

Overview

BFG35 from NXP Semiconductors is an NPN planar epitaxial wideband transistor in SOT223 package, designed for RF amplifier stages up to 4 GHz. It delivers 750 mV output voltage at 793.25 MHz with 15 dB maximum unilateral power gain at 500 MHz and supports 100 mA DC collector current at 10 V V_CE, targeting CATV line amplifiers and broadband signal distribution systems.

For engineers reviewing the BFG35 datasheet, BFG35 pinout, BFG35 application, or BFG35 equivalent, key selection criteria include its 4 GHz f_T, high-output-voltage capability under DIN 45004B intermodulation conditions, thermal resistance of 40 K/W to soldering point, and SOT223 package suitability for heatsink-integrated RF PCB layouts.

Technical Context

The BFG35 employs a planar epitaxial structure optimized for wideband small-signal amplification, with low feedback capacitance (1.2 pF) and emitter capacitance (10 pF) enabling stable gain up to 800 MHz. Its SOT223 package integrates a collector tab for direct thermal coupling to PCB copper planes.

Operation is specified at T_j = 25 °C with V_CE = 10 V and I_C = 100 mA, delivering 15 dB G_UM at 500 MHz and maintaining 11 dB at 800 MHz. Second-order intermodulation distortion reaches −57 dB under 50 dBmV output conditions at 810 MHz two-tone excitation.

Key Specifications

Pinout & Package

SOT223 plastic surface-mounted package with 4 leads and integrated collector heatsink tab; dimensions per JEDEC SC-73 outline: 6.7 × 3.7 × 1.8 mm, 0.8 mm lead pitch, collector tab on lead 4.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BFG35, BFG36,115 offers extended bandwidth at the cost of 2 dB lower midband gain, while MRF581 trades SOT223 thermal integration for higher voltage tolerance and TO-92 mechanical robustness-neither is pin-compatible, requiring layout revision.

Availability

BFG35 is available at Aetrix Electronics and suitable for CATV infrastructure, UHF broadcast distribution, RF test instrumentation, and ISM band wireless sensor nodes requiring stable component supply across multi-year production cycles.

Supply support for BFG35 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 high-performance RF, analog, and interface solutions for communications, automotive, and industrial markets.

The BFG35 belongs to NXP's legacy wideband RF transistor family engineered specifically for linear CATV and broadband signal distribution applications demanding high output voltage and low intermodulation distortion.

FAQ

What is the maximum operating frequency supported by the BFG35?

The BFG35 has a typical transition frequency (f_T) of 4 GHz, verified at I_C = 100 mA and V_CE = 10 V. Its maximum unilateral power gain remains usable up to 800 MHz (11 dB), making it suitable for UHF amplification in CATV and DVB-T systems. Operation beyond 1 GHz requires careful layout and impedance control due to decreasing G_UM.

Does the BFG35 require external neutralization for stability?

No, the BFG35 does not require external neutralization in standard common-emitter configurations. Its low feedback capacitance (C_re = 1.2 pF) and measured S-parameters (S12 < 0.05 at 500 MHz) ensure unconditional stability up to 1 GHz when properly decoupled and matched. Stability analysis using the Rollett K-factor confirms K > 1 across the 100–800 MHz band.

How is thermal management implemented for the BFG35 in PCB design?

The BFG35 uses Pin 4 as a collector tab thermally connected to the die. For optimal thermal performance, this tab must be soldered to ≥1 cm² of 2-ounce copper on the PCB, achieving the rated R_{th j-s} = 40 K/W. Without this copper pour, junction temperature can exceed 175 °C at full 1 W dissipation, risking reliability degradation.

Can the dual-emitter pins (1 and 3) of the BFG35 be used independently?

No, Pins 1 and 3 are internally shorted to the same emitter node. Their dual presence enables low-inductance layout options-such as separate bypass capacitors or symmetric microstrip routing-but they do not provide independent emitter terminals. Using them as separate nodes will cause internal shorting and device failure.

What intermodulation standards does the BFG35 meet in cable TV applications?

The BFG35 meets DIN 45004B intermodulation requirements for CATV systems, delivering −55 dB third-order IMD at 793.25 MHz and −57 dB second-order IMD at 810 MHz under defined two-tone test conditions (Vo = 750 mV, RL = 75 Ω). These results align with SCTE 40-2016 linearity specifications for drop amplifiers.