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NXP Semiconductors BF245A,126
- Part No.:
- BF245A,126
- Manufacturer:
- NXP Semiconductors
- Category:
- Single FETs, MOSFETs
- Package:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Datasheet:
-
BF245A,126.pdf
- Description:
- RF MOSFET JFET 15V TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:7,956
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Product details
Overview
BF245A,126 from NXP Semiconductors is a general-purpose N-channel symmetrical junction field-effect transistor (JFET) in TO-92 variant package, rated for ±30 V drain-source voltage, 2–6.5 mA zero-gate drain current (IDSS), and 700 MHz cut-off frequency (fgfs). It operates as a low-noise, high-frequency amplifying device in RF and audio signal paths, commonly used in HF receiver front-ends and tunable oscillator stages.
For engineers reviewing the BF245A,126 datasheet, BF245A,126 pinout, BF245A,126 application, or BF245A,126 equivalent, key selection considerations include gate-source cut-off voltage range (−0.25 V to −8 V), forward transfer admittance (3–6.5 mS), noise figure (1.5 dB at 100 MHz), thermal resistance (250 K/W), and symmetrical drain/source interchangeability in circuit layout.
Technical Context
The BF245A,126 employs a silicon junction-gate structure with symmetrical source/drain terminals, enabling bidirectional conduction and flexible biasing in common-source, common-drain, or common-gate configurations. Its low Crs (1.1 pF typical) and moderate Cis (4 pF) support stable high-frequency amplification up to 700 MHz.
Static operation relies on depletion-mode behavior: IDSS is defined at VGS = 0 V and VDS = 15 V, while VGSoff is measured at ID = 10 nA and VDS = 15 V. The device exhibits predictable transfer characteristics across temperature (−65 °C to +150 °C) and maintains usable gfs above 200 MHz (6 mS typical).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VDS | ±30 V - maximum allowable drain-source voltage without breakdown; defines safe operating range in amplifier or switch applications. |
| IDSS | 2–6.5 mA - zero-bias drain current; sets DC operating point and gain potential in self-biased amplifier designs. |
| VGSoff | −0.25 to −8 V - gate-source cut-off voltage; determines minimum reverse bias needed to pinch off channel conduction. |
| |yfs| | 3–6.5 mS - forward transfer admittance at 1 kHz; directly correlates to small-signal transconductance and AC gain capability. |
| fgfs | 700 MHz - cut-off frequency where transconductance drops to 70% of its low-frequency value; confirms suitability for HF/VHF amplification. |
| F | 1.5 dB - noise figure at 100 MHz with 1 kΩ source resistance; indicates low-noise performance critical for receiver front-end stages. |
| Rth j-a | 250 K/W - thermal resistance junction-to-ambient in free air; informs heatsinking requirements for continuous 300 mW power dissipation. |
Pinout & Package
BF245A,126 is housed in a plastic TO-92 variant (SOT54) package with through-hole leads and 3-pin single-ended configuration. The package outline conforms to IEC/JEDEC standards, with lead pitch 2.54 mm and body dimensions approx. 4.8 × 4.2 × 5.2 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Drain (d) | Main current-carrying terminal; interchangeable with source in symmetrical JFET operation; connects to load or RF output path. |
| 2 | Source (s) | Reference node for gate bias; interchangeable with drain; often tied to ground or RF choke in common-source amplifiers. |
| 3 | Gate (g) | High-impedance control terminal; requires ESD protection during handling; reverse-biased to set operating point via VGS. |
Key Features
| Feature | Design Value |
|---|---|
| Symmetrical drain/source terminals | Enables bidirectional use in analog switches or phase-invariant amplifier topologies without layout rework. |
| 700 MHz cut-off frequency | Supports stable amplification in HF bands (3–30 MHz) and lower VHF (up to ~100 MHz) with minimal gain roll-off. |
| 1.5 dB noise figure at 100 MHz | Meets low-noise requirements for AM/SW receiver front-ends and crystal oscillator buffer stages. |
| TO-92 variant (SOT54) package | Provides mechanical compatibility with legacy through-hole PCB footprints while maintaining thermal performance up to 300 mW. |
| ±30 V drain-source rating | Allows operation in higher-voltage analog circuits (e.g., tube-style audio preamps or RF detector supplies) without derating. |
Applications
| HF Receiver Front-End | Crystal Oscillator Buffer |
|---|---|
|
Use Scenario: Amplifying weak shortwave signals (3–30 MHz) before mixer stage in communications receivers. IC Role / Device Role / Timing Role: Low-noise common-source amplifier with tuned input matching network. Use Value: 1.5 dB noise figure and 700 MHz fgfs preserve signal integrity and dynamic range in narrowband HF reception. |
Use Scenario: Isolating and driving crystal oscillator output to multiple downstream logic or RF stages. IC Role / Device Role / Timing Role: High-input-impedance buffer amplifier with minimal loading on resonant crystal circuit. Use Value: Symmetrical drain/source and low Crs (1.1 pF) prevent frequency pulling and maintain oscillator stability. |
| Audio Preamp Stage | RF Detector Load |
|
Use Scenario: High-fidelity microphone or phono preamplifier requiring low distortion and wide bandwidth. IC Role / Device Role / Timing Role: Voltage-controlled current source in discrete JFET-based gain block. Use Value: Linear transfer characteristics (Fig.3) and low gate leakage (<5 nA) ensure stable DC bias and low THD. |
Use Scenario: Acting as active load in synchronous AM detector or product detector circuits. IC Role / Device Role / Timing Role: Depletion-mode current sink providing adjustable quiescent current for demodulator diodes. Use Value: Adjustable IDSS (2–6.5 mA) and wide VGSoff range allow precise tail current tuning for optimal detection linearity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar N-channel JFET amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| J310 | Higher IDSS (20–60 mA), lower VGSoff (−0.5 to −3.0 V), smaller Crs (0.8 pF), same TO-92 package. | Better suited for broadband video or fast-switching applications; less ideal for low-current HF biasing. | Select J310 when higher transconductance and faster switching are required; verify bias network compatibility with lower VGSoff. |
| 2N5457 | Lower IDSS (1–5 mA), wider VGSoff (−0.5 to −5.0 V), higher Rth j-a (300 K/W), same TO-92 package. | Preferred for ultra-low-power audio gain stages where thermal margin is constrained. | Choose 2N5457 for battery-powered portable audio where sub-1 mA IDSS and conservative power dissipation are critical. |
Compared with BF245A,126, J310 delivers higher gain-bandwidth but demands tighter gate bias control, while 2N5457 trades off cut-off frequency (≈150 MHz) for superior low-current stability-making BF245A,126 the balanced choice for HF amplification with moderate noise and predictable biasing.
Availability
BF245A,126 is available at Aetrix Electronics and suitable for HF receiver front-ends, crystal oscillator buffers, and audio preamplifier stages requiring stable component supply, long-term obsolescence resilience, and consistent parametric performance across production batches.
Supply support for BF245A,126 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 mixed-signal, RF, and standard logic solutions, with roots in Philips' semiconductor division.
The BF245A,126 belongs to NXP's legacy discrete JFET product line designed for analog signal conditioning in communications, audio, and instrumentation systems where low noise, symmetry, and through-hole reliability are essential.
FAQ
What is the maximum drain-source voltage rating for BF245A,126?
The BF245A,126 has a maximum drain-source voltage (VDS) rating of ±30 V, as specified in the Absolute Maximum Ratings table. This rating applies under all operating conditions and must not be exceeded to avoid permanent device damage. Operation near this limit requires careful attention to transient spikes and PCB layout parasitics that could cause localized overvoltage.
Is BF245A,126 pin-compatible with other variants in the BF245 family?
Yes, BF245A,126 shares identical pinout (drain–source–gate on pins 1–2–3), package (TO-92 variant/SOT54), and footprint with BF245B and BF245C. However, electrical parameters differ significantly-especially IDSS (2–6.5 mA for BF245A,126 vs. 6–15 mA for BF245B)-so direct substitution requires verification of bias network compatibility.
What is the typical noise figure of BF245A,126 and at what conditions is it measured?
The typical noise figure of BF245A,126 is 1.5 dB, measured at 100 MHz with VDS = 15 V, VGS = 0 V, RG = 1 kΩ (common-source configuration), and input tuned for minimum noise. This value reflects its suitability for low-noise HF amplification, though actual system-level noise will depend on source impedance matching and PCB layout.
Can the drain and source terminals of BF245A,126 be interchanged in circuit design?
Yes-the BF245A,126 is a symmetrical junction FET, and its drain and source terminals are functionally interchangeable. This allows flexibility in PCB layout and enables use in bidirectional analog switches or phase-insensitive amplifier configurations without performance penalty.
What thermal resistance does BF245A,126 exhibit in free air, and how does it affect power handling?
BF245A,126 has a junction-to-ambient thermal resistance (Rth j-a) of 250 K/W in free air. At its maximum rated power dissipation of 300 mW, this results in a theoretical junction temperature rise of 75 °C above ambient-meaning operation at full power requires ambient temperatures ≤75 °C to stay within the 150 °C maximum junction limit.
BF245A,126 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Packaging:
- Tape & Box (TB)
- Product Status:
- Obsolete
- Technology:
- JFET
- Configuration:
- N-Channel
- Frequency:
- 100MHz
- Gain:
- -
- Voltage - Test:
- 15 V
- Current Rating (Amps):
- 6.5mA
- Noise Figure:
- 1.5dB
- Current - Test:
- -
- Power - Output:
- -
- Voltage - Rated:
- 30 V
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
BF245A,126 FAQ
1.How can I place an order for BF245A,126 through Aetrix?
Please submit a Request for Quotation (RFQ) for BF245A,126 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 BF245A,126 reliable?
The price and inventory of BF245A,126 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BF245A,126 is usually 5 days.
3.What payment methods are accepted for BF245A,126?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BF245A,126 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BF245A,126?
BF245A,126 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BF245A,126 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 BF245A,126?
For technical support, including BF245A,126 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BF245A,126 requirements.
6.How does Aetrix verify that BF245A,126 is sourced from the original manufacturer or authorized distributors?
All BF245A,126 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 BF245A,126 meets industry standards.
7.What is the process for return or replacement of BF245A,126?
All BF245A,126 units undergo pre-shipment inspection (PSI). If there is an issue with BF245A,126, 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 BF245A,126 part is unused and in its original packaging.
Return procedure for BF245A,126:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BF245A,126 Tags
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SAV-551+
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TAV2-501+
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CE3512K2-C1
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