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NXP Semiconductors BF904R,235
- Part No.:
- BF904R,235
- Manufacturer:
- NXP Semiconductors
- Category:
- Single FETs, MOSFETs
- Package:
- SOT-143R
- Datasheet:
-
BF904R,235.pdf
- Description:
- RF MOSFET 5V SOT143R
- Quantity:
- Payment:
- Shipping:
Inventory:9,786
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Product details
Overview
BF904R,235 from NXP Semiconductors is an N-channel dual-gate MOSFET in SOT143R package, designed for low-noise VHF/UHF amplifier stages operating at 5 V supply. It delivers 25 mS forward transfer admittance (|yfs|), 2.2 pF input capacitance at gate 1, and 2 dB noise figure at 800 MHz-enabling high-gain, low-distortion signal amplification in TV tuners and professional RF receivers.
For engineers reviewing the BF904R,235 datasheet, BF904R,235 pinout, BF904R,235 application, or BF904R,235 equivalent, key selection criteria include its dual-gate AGC capability, cross-modulation performance under variable gain control, thermal resistance of 550 K/W (junction-to-ambient), and guaranteed operation up to 150 °C junction temperature in compact surface-mount layout.
Technical Context
The BF904R,235 integrates two cascaded MOSFET gates with internal biasing to enable precise automatic gain control (AGC) without external components. Gate 1 serves as RF input with low input capacitance (2.2 pF typ.), while gate 2 functions as AGC control node with threshold voltage of 0.3–1.2 V and cut-off current ≤50 nA.
Its short-channel enhancement-mode structure supports stable 10 mA drain current at 5 V drain-source voltage, with forward transfer admittance peaking at 25 mS and maintaining >20 mS across 25–150 °C junction temperature range-critical for wide-temperature RF front-end designs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| |yfs| | 25 mS typical - enables high small-signal gain in narrowband VHF/UHF amplifiers |
| Cig1-s | 2.2 pF typical - minimizes input loading and preserves Q-factor in tuned RF circuits |
| Noise Figure | 2 dB at 800 MHz - ensures high sensitivity in UHF receiver front-ends |
| VDS max | 7 V - supports operation with 3–7 V supply rails common in tuner modules |
| Ptot | 200 mW - defines maximum dissipation with derating above 40 °C ambient |
| Rth j-a | 550 K/W - requires careful PCB copper area planning for thermal management |
| VG1-S(th) | 0.3–1.0 V - allows direct interface with low-voltage AGC control signals |
Pinout & Package
BF904R,235 uses the SOT143R plastic microminiature surface-mount package (3.0 × 1.4 × 1.1 mm), featuring reverse pinning versus SOT143B. The package is optimized for RF layout with minimal lead inductance and controlled parasitic capacitance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | s, b (source & substrate) | Common reference node for both gates and drain; must be DC-grounded and RF-bypassed |
| 2 | d (drain) | RF output node; connects to tuned load or next stage via impedance-matching network |
| 3 | g2 (gate 2) | AGC control input; accepts DC or slow-varying voltage (0.3–4 V) to modulate gain |
| 4 | g1 (gate 1) | RF input node; high-impedance, low-capacitance path requiring 50 Ω source termination |
Key Features
| Feature | Design Value |
|---|---|
| Dual-gate architecture with internal bias | Eliminates external bias resistors, reducing component count and board space in tuner IF/RF stages |
| Low noise figure (2 dB @ 800 MHz) | Preserves signal-to-noise ratio in UHF band reception where interference margins are tight |
| Superior cross-modulation performance | Enables clean multi-channel reception under strong adjacent-signal conditions during AGC operation |
| High |yfs|/Cig1-s ratio | Delivers >11.4 mS/pF - critical for achieving high gain-bandwidth product in compact VHF amplifiers |
| 5 V supply optimization | Guarantees full parameter compliance at 5 V, aligning with standard tuner logic and analog supply rails |
Applications
| Television Tuner Front-End | Professional UHF Receiver |
|---|---|
Use Scenario: Amplifying weak terrestrial or cable TV signals in the 47–862 MHz band before mixer stage. IC Role / Device Role / Timing Role: Low-noise RF amplifier with AGC-controlled gain staging using gate 2 voltage. Use Value: 2 dB noise figure and 25 mS |yfs| ensure high sensitivity and strong channel selectivity without degrading SNR. |
Use Scenario: Signal amplification in portable or fixed-site UHF communications receivers (400–900 MHz). IC Role / Device Role / Timing Role: Dual-gate gain-control amplifier enabling dynamic range compression during signal fading. Use Value: Verified cross-modulation suppression down to −120 dBμV supports reliable multi-signal demodulation in dense RF environments. |
| RF Test Equipment Preamp | Wireless Microphone Receiver |
Use Scenario: Input-stage amplification in handheld spectrum analyzers or signal generators operating up to 1 GHz. IC Role / Device Role / Timing Role: High-linearity, low-noise active probe or input buffer with stable gain over temperature. Use Value: 550 K/W thermal resistance and 150 °C max junction temperature allow continuous operation in compact enclosures. |
Use Scenario: RF amplification in battery-powered wireless microphone receivers (174–216 MHz VHF or 470–698 MHz UHF bands). IC Role / Device Role / Timing Role: Low-power, low-noise first-stage amplifier with AGC tracking fast signal level changes. Use Value: 200 mW power dissipation and 30 mA max drain current support extended runtime on coin-cell or AA batteries. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-gate MOSFET amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BF998,215 | Higher |yfs| (35 mS typ.), lower Cig1-s (1.8 pF), but 300 mW Ptot and SOT143B pinout | Requires PCB redesign due to non-reverse pinning; better suited for new designs needing higher gain | Select BF998,215 only when upgrading gain-bandwidth and thermal headroom is available |
| MRF901T1 | Single-gate LDMOS, 500 MHz fT, 10 dB NF at 450 MHz, TO-236 package | Lacks dual-gate AGC capability; requires external gain control circuitry | Choose MRF901T1 only if system-level AGC is implemented digitally or with separate VCA |
Compared with BF904R,235, BF998,215 offers higher gain but demands layout revision, while MRF901T1 sacrifices integrated AGC for broader frequency coverage-making BF904R,235 uniquely balanced for cost-sensitive, space-constrained VHF/UHF tuner applications requiring analog gain control.
Availability
BF904R,235 is available at Aetrix Electronics and suitable for television tuner modules, professional UHF receivers, and RF test equipment requiring stable component supply, long-lifecycle support, and consistent parametric performance across production batches.
Supply support for BF904R,235 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 secure connectivity solutions for automotive, industrial, and consumer applications, with deep heritage in RF and analog design dating to Philips.
The BF904R,235 belongs to NXP's legacy RF transistor family engineered specifically for high-performance, low-noise VHF/UHF amplifier applications in broadcast and communications equipment.
FAQ
What is the maximum operating junction temperature for BF904R,235?
The BF904R,235 has a maximum operating junction temperature of 150 °C, as specified in the Limiting Values table. This rating assumes proper PCB thermal design per the datasheet's derating curve-where total power dissipation must be reduced linearly above 40 °C ambient temperature to maintain safe junction operation. Thermal resistance from junction to ambient is 550 K/W for the SOT143R package.
Does BF904R,235 support automatic gain control (AGC) functionality?
Yes, BF904R,235 supports analog AGC through gate 2 (pin 3), which accepts a DC control voltage (typically 0.3–4 V) to vary gain while preserving linearity and minimizing cross-modulation. Its internal bias circuit ensures stable AGC response, and Fig.5 in the datasheet shows typical gain reduction vs. AGC voltage at 50 MHz. This eliminates need for external bias networks in tuner designs.
What is the difference between BF904R,235 and BF904,235?
BF904R,235 uses the SOT143R package with reverse pinning (pins 1–4 = s,b / d / g2 / g1), whereas BF904,235 uses SOT143B (pins 1–4 = s,b / d / g1 / g2). Both share identical electrical specifications, but the pinout reversal means they are not interchangeable without PCB layout modification. BF904R,235 marking code is %MD per the datasheet.
Can BF904R,235 operate reliably at 7 V drain-source voltage?
Yes, BF904R,235 is rated for VDS up to 7 V per Absolute Maximum Ratings, but its static and dynamic characteristics-including |yfs|, noise figure, and cross-modulation-are fully characterized only at VDS = 5 V. Operation at 7 V is permissible for transient conditions or margin testing, but sustained use should follow the 5 V recommended operating condition to guarantee specified RF performance.
What is the typical noise figure of BF904R,235 at 200 MHz?
The typical noise figure of BF904R,235 is 1 dB at 200 MHz, measured under conditions of GS = 2 mS and BS = BSopt. This value is explicitly listed in the Dynamic Characteristics table on page 4 of the datasheet and reflects its optimized low-noise performance in the VHF band-complementing its 2 dB noise figure at 800 MHz in the UHF band.
BF904R,235 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- SOT-143R
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Technology:
- MOSFET (Metal Oxide)
- Configuration:
- N-Channel Dual Gate
- Frequency:
- 200MHz
- Gain:
- -
- Voltage - Test:
- 5 V
- Current Rating (Amps):
- 30mA
- Noise Figure:
- 1dB
- Current - Test:
- 10 mA
- Power - Output:
- -
- Voltage - Rated:
- 7 V
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-143R
BF904R,235 FAQ
1.How can I place an order for BF904R,235 through Aetrix?
Please submit a Request for Quotation (RFQ) for BF904R,235 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 BF904R,235 reliable?
The price and inventory of BF904R,235 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BF904R,235 is usually 5 days.
3.What payment methods are accepted for BF904R,235?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BF904R,235 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BF904R,235?
BF904R,235 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BF904R,235 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 BF904R,235?
For technical support, including BF904R,235 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BF904R,235 requirements.
6.How does Aetrix verify that BF904R,235 is sourced from the original manufacturer or authorized distributors?
All BF904R,235 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 BF904R,235 meets industry standards.
7.What is the process for return or replacement of BF904R,235?
All BF904R,235 units undergo pre-shipment inspection (PSI). If there is an issue with BF904R,235, 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 BF904R,235 part is unused and in its original packaging.
Return procedure for BF904R,235:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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