NXP Semiconductors BF998R,215

Overview

BF998R,215 from NXP Semiconductors is a silicon N-channel dual-gate MOSFET in SOT143R package, designed for low-noise RF amplification up to 800 MHz with 1 dB noise figure at 800 MHz, 24 mS forward transfer admittance, and 2.1 pF gate-1 input capacitance. It operates at 12 V supply voltage and delivers stable gain control in VHF/UHF tuner front-ends.

For engineers reviewing the BF998R,215 datasheet, BF998R,215 pinout, BF998R,215 application, or BF998R,215 equivalent, key selection criteria include noise performance at UHF frequencies, dual-gate AGC capability, thermal resistance (500 K/W on ceramic substrate), and SOT143R reverse-pinout compatibility with high-frequency PCB layout constraints.

Technical Context

The BF998R,215 uses a depletion-mode dual-gate structure with source and substrate internally connected, enabling independent biasing of gate 1 (signal input) and gate 2 (gain control). Its integrated back-to-back diodes protect gate inputs against ESD surges during handling.

It achieves automatic gain control via variable gate-1 voltage while maintaining constant transconductance across drain currents from 2 mA to 18 mA, with typical |yfs| = 24 mS at ID = 10 mA, VDS = 8 V, and VG2–S = 4 V - optimized for 200–800 MHz TV tuner and professional comms applications.

Key Specifications

Pinout & Package

BF998R,215 is housed in a plastic surface-mounted SOT143R package (SC-61AA), featuring reverse pinning versus SOT143B: Pin 1 = source (s,b), Pin 2 = drain (d), Pin 3 = gate 2 (g2), Pin 4 = gate 1 (g1). The package measures 3.0 × 1.4 × 1.1 mm with 0.95 mm lead pitch and is rated for 150 °C junction temperature.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-gate RF amplifier applications.

Compared with BF998,215 and MRF901LT1, the BF998R,215 uniquely combines SOT143R reverse pinout compatibility, sub-1 dB noise at UHF, and native dual-gate AGC - making it irreplaceable in space-constrained, cost-sensitive tuner modules where layout reuse and sensitivity are paramount.

Availability

BF998R,215 is available at Aetrix Electronics and suitable for television tuner front-ends, professional UHF transceivers, VHF aircraft band receivers, and UHF RFID reader designs requiring stable component supply and long-term obsolescence management.

Supply support for BF998R,215 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 RF, analog, and mixed-signal solutions for consumer, industrial, and communications markets.

The BF998R,215 belongs to NXP's legacy RF transistor product line, engineered specifically for low-noise, gain-controllable amplification in VHF/UHF broadcast and professional wireless equipment.

FAQ

What is the maximum operating frequency supported by the BF998R,215?

The BF998R,215 is characterized for low-noise amplification up to 800 MHz, with specified noise figure (1.0 dB) and forward transfer admittance (24 mS) validated at that frequency. While usable beyond 800 MHz, gain and noise performance degrade above this point per Figures 13–15 in the datasheet. For reliable operation, the BF998R,215 should be applied within its tested 200–800 MHz range.

How does the BF998R,215 differ from the BF998,215 in terms of pinout and layout compatibility?

The BF998R,215 uses SOT143R packaging with reverse pinning: pin 1 = source (s,b), pin 2 = drain (d), pin 3 = gate 2 (g2), pin 4 = gate 1 (g1). In contrast, the BF998,215 uses SOT143B with standard pinning: pin 1 = gate 1 (g1), pin 2 = drain (d), pin 3 = gate 2 (g2), pin 4 = source (s,b). This means the BF998R,215 is not layout-compatible with BF998,215 without PCB revision.

Can the BF998R,215 be used in automatic gain control (AGC) circuits, and how is it implemented?

Yes, the BF998R,215 supports AGC via gate 1 (pin 4), where applying a variable negative voltage (0 V to –2 V) modulates gain linearly - demonstrated in Figures 19–20 with >40 dB gain control range. Gate 2 (pin 3) is held at +4 V for optimal transconductance. This dual-gate configuration allows the BF998R,215 to serve as a self-contained AGC amplifier without external components.

What thermal derating applies to the BF998R,215 at elevated ambient temperatures?

The BF998R,215 has a total power dissipation limit of 200 mW up to Tamb = 50 °C, as shown in Figure 4. Above 50 °C, power must be linearly derated at 4 mW/°C (based on Rth j-a = 500 K/W). At 70 °C ambient, maximum allowable dissipation drops to 120 mW. This derating ensures junction temperature remains below 150 °C under continuous operation.

Does the BF998R,215 require external ESD protection, given its integrated back-to-back diodes?

The BF998R,215 includes integrated back-to-back diodes between each gate and source, rated for ±10 mA surge current - sufficient for handling typical handling and board-level ESD events. However, for systems exposed to IEC 61000-4-2 Level 4 (8 kV contact), external transient voltage suppression on gate lines is still recommended. The internal diodes protect the BF998R,215 itself but do not replace system-level ESD compliance measures.