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NXP Semiconductors BF245B,126
- Part No.:
- BF245B,126
- Manufacturer:
- NXP Semiconductors
- Category:
- Single FETs, MOSFETs
- Package:
- TO-226-3, TO-92-3 (TO-226AA) Formed Leads
- Datasheet:
-
BF245B,126.pdf
- Description:
- RF MOSFET JFET 15V TO92-3
- Quantity:
- Payment:
- Shipping:
Inventory:7,133
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Product details
Overview
BF245B,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, 6–15 mA zero-gate drain current (IDSS), and 700 MHz cut-off frequency (fgfs). It operates as a low-noise RF amplifier stage in HF receiver front-ends and broadband DC-coupled gain blocks.
For engineers reviewing the BF245B,126 datasheet, BF245B,126 pinout, BF245B,126 application, or BF245B,126 equivalent, key selection criteria include gate-source cut-off voltage range (−1.6 V to −3.8 V), forward transfer admittance (3–6.5 mS), reverse transfer capacitance (1.1 pF), and thermal resistance (200–250 K/W), all critical for stable biasing and high-frequency small-signal performance.
Technical Context
The BF245B,126 uses a symmetrical JFET structure enabling interchangeable drain and source connections in circuit design, simplifying layout in bidirectional analog switches and cascode configurations. Its silicon junction construction delivers predictable transfer characteristics with typical VGSoff between −1.6 V and −3.8 V at ID = 10 nA and VDS = 15 V.
Designed for operation up to 700 MHz, it exhibits low noise figure (1.5 dB at 100 MHz), low Crs (1.1 pF), and stable yfs across frequency-enabling use in tunable LF/HF amplifiers without external neutralization. Static and dynamic parameters are specified at Tamb = 25 °C and Tj = 25 °C, with derated power dissipation above 75 °C ambient.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VDS | ±30 V - supports rail-to-rail signal swing in single-supply amplifier stages up to ±30 V supply rails |
| IDSS | 6–15 mA - defines quiescent operating point and sets transconductance for linear gain control |
| VGSoff | −1.6 to −3.8 V - determines minimum gate bias required to pinch off channel; critical for setting DC operating point |
| fgfs | 700 MHz - usable as RF amplifier up to VHF band without gain roll-off in common-source configuration |
| Crs | 1.1 pF - low reverse transfer capacitance minimizes Miller effect and enables stable high-frequency amplification |
| F (noise figure) | 1.5 dB at 100 MHz - enables low-noise preamplification in HF receivers and spectrum analyzer front-ends |
| Rth j-a | 200–250 K/W - requires minimal heatsinking on PCB; 10 mm × 10 mm copper pad recommended for drain lead |
Pinout & Package
BF245B,126 is housed in a plastic TO-92 variant (SOT54) through-hole package with 3 leads, optimized for manual assembly and prototyping. The package features uncontrolled terminal dimensions near the molding compound edge per JEDEC standards.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Drain (d) | Main current-carrying terminal; connects to load resistor or RF choke; thermally coupled to PCB copper for heat dissipation |
| 2 | Source (s) | Reference node for gate bias; often tied to ground or source degeneration resistor; interchangeable with drain in symmetrical operation |
| 3 | Gate (g) | High-impedance control terminal; requires ESD protection during handling; biased via high-value resistor network to set VGS |
Key Features
| Feature | Design Value |
|---|---|
| Symmetrical drain/source terminals | Enables bidirectional signal flow and simplifies cascode or analog switch implementation without polarity constraints |
| 700 MHz cut-off frequency | Supports wideband amplification from DC to VHF without external tuning components in common-source topology |
| Low 1.1 pF Crs | Reduces feedback path in high-gain stages, eliminating need for neutralization in HF amplifier designs |
| 1.5 dB noise figure at 100 MHz | Meets sensitivity requirements for HF communications receivers and spectrum monitoring front-ends |
| TO-92 variant (SOT54) package | Compatible with standard through-hole PCB footprints and hand-soldering; includes antistatic packaging for gate protection |
Applications
| HF Receiver Front-End | DC-Coupled Instrumentation Amplifier |
|---|---|
Use Scenario: First-stage low-noise amplification in shortwave radio receivers operating from 3–30 MHz. IC Role / Device Role / Timing Role: N-channel JFET configured as common-source amplifier with self-bias network. Use Value: 1.5 dB noise figure and 700 MHz fgfs ensure high signal-to-noise ratio and broadband response without neutralization. |
Use Scenario: Input stage of precision DC-coupled oscilloscope vertical amplifier requiring high input impedance and low drift. IC Role / Device Role / Timing Role: Symmetrical JFET used in differential pair with matched VGSoff for offset cancellation. Use Value: Interchangeable drain/source allows flexible biasing and improves CMRR in discrete op-amp topologies. |
| RF Signal Generator Output Buffer | Audio Frequency Preamp Stage |
Use Scenario: Final gain stage in benchtop RF signal generator delivering 0–250 MHz output with flat amplitude response. IC Role / Device Role / Timing Role: Common-source JFET buffer isolating VCO core from variable load impedance. Use Value: Low Crs (1.1 pF) and high yfs (6 mS at 200 MHz) maintain gain flatness and minimize load-pull effects. |
Use Scenario: High-fidelity microphone preamplifier in studio audio equipment requiring ultra-low noise and wide bandwidth. IC Role / Device Role / Timing Role: Single-ended JFET gain stage with source degeneration for linearity and gain stability. Use Value: 3–6.5 mS forward transfer admittance provides adjustable gain while maintaining THD < 0.1% at 1 kHz. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 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 TO-92 footprint but same pinout | Better suited for higher-current, lower-voltage biasing; less ideal for low-noise HF where BF245B,126's tighter VGSoff distribution matters | Select J310 when designing for 12 V systems with aggressive gain targets; retain BF245B,126 for HF noise-critical or legacy bias networks |
| 2N5457 | Lower IDSS (1–5 mA), wider VGSoff range (−0.5 to −5.0 V), identical TO-92 package and pinout | Preferred for ultra-low-power DC amplifiers or high-impedance sensor interfaces where lower quiescent current is essential | Choose 2N5457 for battery-powered instrumentation; BF245B,126 remains optimal for HF amplification requiring >6 mA IDSS and 1.5 dB noise performance |
Compared with J310 and 2N5457, BF245B,126 occupies a mid-range IDSS and VGSoff sweet spot-delivering balanced gain, noise, and bias stability for HF and broadband analog circuits where neither extreme low-current nor high-current operation is required.
Availability
BF245B,126 is available at Aetrix Electronics and suitable for HF receiver front-ends, DC-coupled instrumentation amplifiers, and RF signal generator output buffers requiring stable component supply and long-term obsolescence management.
Supply support for BF245B,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 leader specializing in high-performance mixed-signal, RF, and standard logic solutions for automotive, industrial, and consumer markets.
The BF245B,126 belongs to NXP's legacy discrete JFET family designed for general-purpose analog signal conditioning-emphasizing reliability, consistent parametric spread, and ease of integration into cost-sensitive RF and audio circuits.
FAQ
What is the maximum drain-source voltage rating for BF245B,126?
The BF245B,126 has a maximum drain-source voltage (VDS) rating of ±30 V, as defined in its Absolute Maximum Ratings table. This rating applies under continuous DC conditions with proper PCB thermal management-specifically, a minimum 10 mm × 10 mm copper pad for the drain lead and ≥3 mm lead length. Exceeding ±30 V risks permanent junction breakdown.
Does BF245B,126 support interchangeable drain and source connections?
Yes, BF245B,126 is a symmetrical N-channel JFET, meaning its drain and source terminals are functionally interchangeable in circuit design. This feature simplifies layout in analog switches, cascode amplifiers, and bidirectional signal paths-provided gate biasing remains referenced to the chosen source node. Pin 1 is labeled "d" and Pin 2 "s", but swapping them does not affect device operation.
What is the typical noise figure of BF245B,126 and at what frequency is it measured?
The typical noise figure of BF245B,126 is 1.5 dB, measured at 100 MHz under common-source configuration with VDS = 15 V, VGS = 0 V, RG = 1 kΩ, and input tuned for minimum noise. This value is confirmed in Figure 21 of the official NXP datasheet and reflects its suitability for HF receiver preamplifiers where signal integrity at weak-input levels is critical.
Can BF245B,126 be used in surface-mount designs?
No, BF245B,126 is only available in the through-hole TO-92 variant (SOT54) package and is not offered in surface-mount variants. Its mechanical outline, lead spacing (2.54 mm), and thermal design assume PCB mounting with axial leads and copper pad heat sinking. For SMT alternatives, engineers should evaluate functionally similar JFETs like the MMBFJ310 or SSM2210, though parametric alignment with BF245B,126 requires careful validation.
What is the gate-source cut-off voltage range for BF245B,126?
The gate-source cut-off voltage (VGSoff) for BF245B,126 ranges from −1.6 V to −3.8 V, specified at ID = 10 nA and VDS = 15 V. This parameter defines the gate bias needed to fully deplete the channel and is critical for establishing stable DC operating points in amplifier and switch applications. The datasheet confirms this range in both STATIC CHARACTERISTICS and QUICK REFERENCE DATA sections.
BF245B,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):
- 15mA
- Noise Figure:
- 1.5dB
- Current - Test:
- -
- Power - Output:
- -
- Voltage - Rated:
- 30 V
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-92-3
BF245B,126 FAQ
1.How can I place an order for BF245B,126 through Aetrix?
Please submit a Request for Quotation (RFQ) for BF245B,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 BF245B,126 reliable?
The price and inventory of BF245B,126 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BF245B,126 is usually 5 days.
3.What payment methods are accepted for BF245B,126?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BF245B,126 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BF245B,126?
BF245B,126 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BF245B,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 BF245B,126?
For technical support, including BF245B,126 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BF245B,126 requirements.
6.How does Aetrix verify that BF245B,126 is sourced from the original manufacturer or authorized distributors?
All BF245B,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 BF245B,126 meets industry standards.
7.What is the process for return or replacement of BF245B,126?
All BF245B,126 units undergo pre-shipment inspection (PSI). If there is an issue with BF245B,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 BF245B,126 part is unused and in its original packaging.
Return procedure for BF245B,126:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
BF245B,126 Tags
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