Infineon Technologies BFR35AP

Overview

BFR35AP from Infineon Technologies is a low-noise silicon bipolar RF transistor designed for broadband amplifier and oscillator stages up to 2 GHz, with verified f_T ≥ 3.5 GHz, NF_min = 1.4 dB at 900 MHz, and G_ma = 16 dB at 900 MHz; used in cellular front-end LNA modules and VHF/UHF signal generators.

For engineers reviewing the BFR35AP datasheet, BFR35AP pinout, BFR35AP application, or BFR35AP equivalent, key selection criteria include noise figure at 2 mA bias, transition frequency under 15 mA/8 V conditions, SOT23 thermal resistance (R_thJS = 205 K/W), and AEC-Q101 qualification status for automotive RF subsystems.

Technical Context

This NPN RF transistor operates in common-emitter configuration with emitter-grounded AC testing per JEDEC JESD-22-A114. Its f_T of 5 GHz (typ.) and C_cb = 0.39 pF (typ.) enable stable gain above 1.8 GHz while maintaining <1.4 dB NF_min at 900 MHz under matched source impedance.

DC characteristics are specified across 0.5–20 mA I_C range, with h_FE = 70–140 at 15 mA/8 V and V_(BR)CEO = 15 V. Thermal derating follows P_tot = 280 mW at T_S ≤ 93 °C, dropping linearly to zero at 120 °C solder-point temperature.

Key Specifications

Pinout & Package

SOT23 plastic surface-mount package with gull-wing leads; 1.3 mm × 2.9 mm footprint, 1.1 mm height, RoHS-compliant matte tin lead finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise RF transistor applications.

Compared with BFR35AP, BFR92A offers superior noise and bandwidth for precision receivers, while MRF581 trades noise performance for higher saturated output-making BFR35AP the balanced choice for cost-sensitive, medium-gain 2 GHz broadband designs.

Availability

BFR35AP is available at Aetrix Electronics and suitable for cellular front-end LNAs, UHF wireless microphone transmitters, VHF oscillator cores, and ISM-band sensor transceivers requiring stable component supply across automotive, industrial, and consumer production programs.

Supply support for BFR35AP 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

Infineon Technologies AG is a German semiconductor manufacturer specializing in power management, automotive electronics, and RF solutions, with global R&D centers and ISO/TS 16949-certified wafer fabs.

The BFR35AP belongs to Infineon's legacy bipolar RF transistor family, engineered specifically for high-linearity, low-noise amplification in sub-3 GHz wireless infrastructure and portable radio equipment.

FAQ

What is the recommended bias condition for minimum noise figure?

The BFR35AP achieves NF_min = 1.4 dB at 900 MHz with I_C = 2 mA and V_CE = 6 V. Source impedance must be matched to Z_Sopt ≈ 15 + j12 Ω (50 Ω system), typically implemented using a shunt inductor and series capacitor network on the base feed line.

Is the BFR35AP qualified for automotive use?

Yes-the BFR35AP carries full AEC-Q101 qualification per Infineon's published report, including HTOL, temperature cycling, and ESD HBM testing. It is approved for use in automotive infotainment RF front-ends and telematics antenna modules.

How does thermal resistance affect maximum RF output power?

With R_thJS = 205 K/W and T_J max = 150 °C, sustained RF output is limited to ~180 mW at T_S = 75 °C. Exceeding this requires either reduced duty cycle or enhanced PCB copper area to lower effective R_thJS.

Can the BFR35AP replace the BFR90 in existing designs?

No-BFR90 has V_CEO = 25 V and f_T = 2.5 GHz, while BFR35AP has V_CEO = 15 V and f_T ≥ 3.5 GHz. Direct substitution risks overvoltage failure; redesign of bias network and matching is required for safe migration.