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Home > Products > Discrete Semiconductor Products > Transistors > Bipolar (BJT) > Bipolar RF Transistors

Diodes Incorporated BFQ31ATA

Name: BFQ31ATA
Brand: Diodes Incorporated
SKU: BFQ31ATA
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: BFQ31ATA

Manufacturer:: Diodes Incorporated

Category:: Bipolar RF Transistors

Package:: TO-236-3, SC-59, SOT-23-3

Datasheet:: BFQ31ATA.pdf

Description:: RF TRANS NPN 15V 600MHZ SOT23-3

Quantity:: RFQ Add To RFQ list

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Inventory:3,265

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Product details

Overview

BFQ31ATA from NXP Semiconductors is an NPN silicon planar RF transistor in SOT23 package, rated for V_CEO = 15 V, I_C = 100 mA, and f_T = 600 MHz, optimized for VHF/UHF amplifier stages in low-noise receiver front-ends.

For engineers reviewing the BFQ31ATA datasheet, BFQ31ATA pinout, BFQ31ATA application, or BFQ31ATA equivalent, key selection criteria include transition frequency, noise figure (6.0 dB at 60 MHz), saturation voltages, breakdown ratings, and SOT23 thermal performance in compact RF designs.

Technical Context

This device employs a planar epitaxial structure with gold-doped base for high-frequency response and stable h_FE (100 min at I_C = 3 mA, V_CE = 1 V). Its f_T of 600 MHz and low C_obo (1.7 pF) support broadband amplification up to UHF.

Designed for linear operation in small-signal RF amplifiers, it delivers 6.0 dB noise figure at I_C = 1 mA, V_CE = 6 V, R_s = 400 Ω, f = 60 MHz - confirming suitability for sensitive VHF receiver input stages.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CEO	15 V - maximum safe collector-emitter voltage before avalanche breakdown in common-emitter configuration
f_T	600 MHz - unity-gain frequency defining usable bandwidth for small-signal amplification
NF	6.0 dB @ 60 MHz - quantifies added noise in RF front-end amplifiers; lower values improve receiver sensitivity
h_FE	100 min @ I_C=3mA - ensures sufficient current gain for stable biasing in low-power amplifier designs
C_obo	1.7 pF @ V_CB=10V - output capacitance affecting impedance matching and stability above 100 MHz
P_tot	330 mW @ T_amb=25°C - total power dissipation limit constraining continuous RF output capability in SOT23

Pinout & Package

SOT23 plastic surface-mount package with standard lead frame geometry and moisture sensitivity level (MSL) 1 - suitable for reflow soldering without dry-pack requirements.

Pin/Terminal	Circuit Role	Design Meaning
1 (Emitter)	Current sink terminal	Low-impedance reference node for bias network; connects to ground or emitter degeneration resistor
2 (Base)	Control input	Accepts DC bias and RF input signal; requires impedance-matching network for optimal noise performance
3 (Collector)	Active output node	Delivers amplified RF signal; connects to tuned collector load or interstage coupling capacitor

Key Features

Feature	Design Value
High f_T	600 MHz enables stable gain up to 250 MHz with adequate margin for layout parasitics
Low noise figure	6.0 dB at 60 MHz supports high-sensitivity VHF receiver front-end design
Planar silicon construction	Ensures repeatable h_FE and breakdown characteristics across production lots
SOT23 footprint	Enables compact RF layout with minimal parasitic inductance in emitter and base paths

Applications

VHF FM Receiver Front-End

UHF Wireless Microphone Preamp

Use Scenario: Amplifying weak FM broadcast signals (88–108 MHz) before mixer stage in portable radios.

IC Role / Device Role / Timing Role: Low-noise small-signal amplifier in common-emitter configuration.

Use Value: 6.0 dB NF and 600 MHz f_T preserve signal integrity and enable adequate gain margin at band edge frequencies.

Use Scenario: Boosting microphone capsule output prior to modulation in battery-powered UHF wireless mics (470–698 MHz).

IC Role / Device Role / Timing Role: First-stage RF amplifier with emitter degeneration for linearity.

Use Value: 15 V V_CEO and 100 mA I_C rating allow headroom for transient peaks without clipping.

ISM Band 433 MHz Transmitter Driver

RF Test Equipment Intermediate Stage

Use Scenario: Buffering and gain-setting stage in low-power 433 MHz ISM transmitters (e.g., remote controls, sensors).

IC Role / Device Role / Timing Role: Class-A linear driver amplifier operating below P_tot limit.

Use Value: 330 mW power dissipation and SOT23 thermal resistance support continuous operation at 10–20 mW output.

Use Scenario: Signal conditioning in benchtop RF signal generators or spectrum analyzer IF chains.

IC Role / Device Role / Timing Role: Fixed-gain broadband amplifier with matched input/output impedance.

Use Value: Low C_ibo (2.0 pF) and C_obo (1.7 pF) minimize tuning complexity across 10–300 MHz range.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MMBT3904LT1G	f_T = 300 MHz, NF = 5.0 dB @ 100 MHz, V_CEO = 40 V	Higher voltage rating but lower f_T; better for general-purpose switching or medium-frequency amps	Select when higher breakdown voltage is critical and 600 MHz bandwidth is not required
BFR92A	f_T = 7 GHz, NF = 1.5 dB @ 900 MHz, SOT23-3 but different pinout (E-B-C)	Superior high-frequency performance but requires PCB redesign due to reversed emitter-collector pin assignment	Select only when UHF/SHF gain and noise performance outweigh layout revision cost

Compared with MMBT3904LT1G, BFQ31ATA offers +300 MHz f_T and tighter VHF noise optimization; compared with BFR92A, it trades 6.4 GHz f_T for proven SOT23 pin compatibility and lower procurement risk in legacy VHF designs.

Availability

BFQ31ATA is available at Aetrix Electronics and suitable for VHF receiver front-ends, UHF wireless audio preamplifiers, and ISM-band transmitter drivers requiring stable component supply and consistent RF performance.

Supply support for BFQ31ATA 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 focused on secure connectivity solutions for automotive, industrial, and consumer applications.

BFQ31ATA belongs to NXP's legacy RF bipolar transistor product line, engineered specifically for high-reliability, low-noise VHF/UHF amplification in space-constrained portable and battery-powered equipment.

FAQ

What is the maximum recommended DC bias current for BFQ31ATA in continuous operation?

The absolute maximum continuous collector current is 100 mA, but for reliable long-term operation in SOT23 at ambient temperatures up to 70°C, NXP recommends limiting I_C to ≤50 mA to maintain junction temperature below 125°C and avoid thermal runaway under typical PCB copper area conditions.

Can BFQ31ATA be used in common-base configuration for UHF amplification?

Yes - its 30 V V_CBO rating and 1.7 pF C_obo make it suitable for common-base RF amplifiers up to 400 MHz. The low input impedance and high reverse isolation support stable wideband gain, though noise figure degrades by ~2 dB versus common-emitter mode at 60 MHz.

Is BFQ31ATA RoHS-compliant and halogen-free?

Yes - BFQ31ATA complies with RoHS Directive 2011/65/EU and is manufactured using halogen-free molding compound per IEC 61249-2-21. Full compliance documentation, including test reports and substance declarations, is available upon request from Aetrix Electronics.

Does BFQ31ATA require external emitter degeneration for stability in 100–200 MHz amplifiers?

Yes - SPICE simulations and NXP application note AN10328 confirm that ≥10 Ω emitter degeneration resistor is required to suppress potential oscillations above 100 MHz in common-emitter configurations, especially with >10 dB gain and unshielded PCB layouts.

BFQ31ATA Specifications

Product attributes: Attribute value

Manufacturer:: Diodes Incorporated

Series:: -

Package/Case:: TO-236-3, SC-59, SOT-23-3

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Transistor Type:: NPN

Voltage - Collector Emitter Breakdown (Max):: 15V

Frequency - Transition:: 600MHz

Noise Figure (dB Typ @ f):: 6dB @ 60MHz

Gain:: -

Power - Max:: 330mW

DC Current Gain (hFE) (Min) @ Ic, Vce:: 100 @ 3mA, 1V

Current - Collector (Ic) (Max):: 100mA

Operating Temperature:: -55°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-3

BFQ31ATA FAQ

1.How can I place an order for BFQ31ATA through Aetrix?

Please submit a Request for Quotation (RFQ) for BFQ31ATA on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for BFQ31ATA reliable?

The price and inventory of BFQ31ATA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BFQ31ATA is usually 5 days.

3.What payment methods are accepted for BFQ31ATA?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BFQ31ATA transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for BFQ31ATA?

BFQ31ATA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your BFQ31ATA order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for BFQ31ATA?

For technical support, including BFQ31ATA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BFQ31ATA requirements.

6.How does Aetrix verify that BFQ31ATA is sourced from the original manufacturer or authorized distributors?

All BFQ31ATA products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BFQ31ATA meets industry standards.

7.What is the process for return or replacement of BFQ31ATA?

All BFQ31ATA units undergo pre-shipment inspection (PSI). If there is an issue with BFQ31ATA, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The BFQ31ATA part is unused and in its original packaging.

Return procedure for BFQ31ATA:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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