NXP Semiconductors BFQ19,115

Overview

BFQ19 from NXP Semiconductors is an NPN silicon RF transistor in SOT89 package, designed for UHF/microwave amplification with 5.5 GHz transition frequency (f_T), 3.3 dB noise figure at 500 MHz, and 11.5 dB maximum unilateral power gain (G_UM) under 50 mA/10 V bias. It serves as a low-distortion, high-gain active device in aerial amplifiers and spectrum analyzers.

For engineers reviewing the BFQ19 datasheet, BFQ19 pinout, BFQ19 application, or BFQ19 equivalent, key selection criteria include its 15 V V_CEO, 100 mA I_C, 1 W P_tot, SOT89 thermal performance (R_{th j-s} = 30 K/W), and verified wideband operation up to 5 GHz.

Technical Context

The BFQ19 employs a planar epitaxial NPN structure optimized for high-frequency linearity and low intermodulation distortion. Its f_T of 5.5 GHz and G_UM of 11.5 dB at 500 MHz confirm suitability for broadband small-signal amplification in the UHF band.

Thermal design relies on the SOT89 collector tab soldered directly to PCB copper for junction-to-solder-point thermal resistance of 30 K/W. Bias stability is supported by h_FE range of 25–80 at 70 mA/10 V and low C_re (1.3 pF) to minimize feedback effects.

Key Specifications

Pinout & Package

SOT89 plastic surface-mounted package with exposed collector pad for thermal conduction; 3-lead configuration compliant with IEC 60196-4 (TO-243) and JEITA ED-7401B (SC-62).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BFQ19, BFR92A trades thermal robustness for higher f_T in a smaller package, while MRF581 offers greater power margin at reduced frequency capability and legacy packaging-neither is pin-compatible, requiring layout revision for substitution.

Availability

BFQ19 is available at Aetrix Electronics and suitable for aerial amplifiers, radar receivers, oscilloscope input stages, and spectrum analyzer IF modules requiring stable component supply across industrial and test equipment lifecycles.

Supply support for BFQ19 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 BFQ19 belongs to NXP's legacy RF transistor product line, engineered specifically for high-linearity, low-noise amplification in UHF and microwave instrumentation and broadcast infrastructure.

FAQ

What is the maximum DC collector current rating for the BFQ19?

The BFQ19 has a maximum DC collector current (I_C) rating of 100 mA, as specified in the Absolute Maximum Ratings table. This value defines the upper limit for continuous DC bias conditions. Exceeding this current may cause thermal runaway or permanent degradation. The BFQ19 is typically operated at 50–70 mA for optimal noise and gain performance, and the 100 mA rating provides headroom for transient peaks. Always verify thermal design using R_{th j-s} = 30 K/W when applying the BFQ19 in production circuits.

Does the BFQ19 require external neutralization for stable operation?

Yes, the BFQ19's feedback capacitance (C_re = 1.3 pF) can induce instability in high-gain amplifier configurations, especially above 500 MHz. Neutralization-typically via a capacitive or inductive path from collector to base-is recommended for unconditional stability in broadband designs. The BFQ19 datasheet does not integrate internal neutralization, so external compensation networks must be implemented based on measured S-parameters. This requirement applies directly to all BFQ19 implementations where G_UM exceeds 8 dB.

What is the thermal resistance from junction to solder point for the BFQ19?

The BFQ19 has a thermal resistance from junction to solder point (R_{th j-s}) of 30 K/W, measured up to a solder point temperature (T_s) of 145 °C. This parameter assumes the collector tab (Pin 2) is fully soldered to a thermally robust PCB copper area. It enables the BFQ19 to safely dissipate its full 1 W rated power with a 30 °C temperature rise above the PCB pad. Proper thermal land design-minimum 100 mm² copper, 2 oz thickness-is essential to achieve this R_{th j-s} in practice for the BFQ19.

Can the BFQ19 be used in Class AB amplifier configurations?

The BFQ19 is characterized and optimized for Class-A operation, with published gain, noise, and linearity data at 50–70 mA DC bias. While it can be biased in Class AB, doing so increases intermodulation distortion and degrades noise figure due to nonlinear h_FE variation near cutoff. The BFQ19 datasheet does not provide Class AB characterization curves or recommendations. For Class AB use, thorough prototyping and distortion testing are required-designers should not assume the BFQ19 maintains its 3.3 dB noise figure or 11.5 dB G_UM under asymmetric bias.

Is the BFQ19 RoHS compliant?

Yes, the BFQ19 is RoHS compliant per EU Directive 2011/65/EU, as confirmed by NXP's material declarations and packaging documentation dated after 2006. The SOT89 package uses lead-free molding compound and termination finish. NXP transitioned all legacy Philips semiconductor products-including the BFQ19-to RoHS-compliant manufacturing by Q3 2006. No exemptions apply, and the BFQ19 contains no restricted substances above threshold limits. Full compliance documentation is available upon request for the BFQ19.