STMicroelectronics START499ETR

Overview

START499ETR from STMicroelectronics is an NPN RF silicon transistor optimized for high-frequency power amplification up to 5 GHz, featuring 42 GHz transition frequency (f_T), 15 dB typical power gain at 1.8 GHz, and 23.5 dBm 1dB compression point under 200 mA / 3 V bias. It delivers 68% collector efficiency in Class-AB operation at 1.9 GHz and is packaged in lead-free SOT-343 (SC-70) for compact wireless front-ends.

For engineers reviewing the START499ETR datasheet, START499ETR pinout, START499ETR application, or START499ETR equivalent, key selection criteria include its f_T, P-1dB, IP3 (33.5 dBm), noise figure (3.3 dB), and SOT-343 thermal resistance (150 °C/W) - all critical for 2.4–2.5 GHz PA stage design in Bluetooth™ and WLAN systems.

Technical Context

The START499ETR employs ST's third-generation bipolar RF process, enabling GaAs-class performance in silicon. Its f_T of 42 GHz and f_max > 60 GHz support stable gain and linearity through 2.5 GHz while maintaining low noise and high efficiency.

Designed for common-emitter configuration with fixed 3-pin functional layout (Base, Collector, Emitter), it operates in Class-AB with I_CQ = 5 mA quiescent bias and supports linear/nonlinear modes via adjustable V_CE (up to 4.5 V) and I_C (up to 600 mA).

Key Specifications

Pinout & Package

SOT-343 (SC-70) is a 4-lead ultra-miniature surface-mount package with two emitter terminals internally bonded together for reduced parasitic inductance and improved RF performance. Lead-free construction complies with ECOPACK® environmental standards.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN RF transistor applications.

Compared with NE68133 and BFP640, START499ETR offers the best balance of 42 GHz f_T, 23.5 dBm P-1dB, and 3.3 dB NF in SOT-343 - making it optimal for cost-sensitive, battery-powered 2.4 GHz transmitters needing both efficiency and spectral purity.

Availability

START499ETR is available at Aetrix Electronics and suitable for DECT handsets, 2.4 GHz WLAN modules, and UHF-VHF pre-power amplifiers requiring stable component supply, consistent parametric performance, and long-term manufacturability in lead-free SMT assembly.

Supply support for START499ETR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The START family targets high-frequency RF power amplification in silicon, specifically addressing the need for GaAs-level performance at lower cost and higher integration readiness in S-band and ISM-band wireless infrastructure and portable devices.

FAQ

What is the recommended DC bias for optimal 2.4 GHz PA performance?

For 2.4 GHz WLAN applications, ST specifies V_CE = 3 V, I_C = 200 mA, and I_B ≈ 1.25 mA (h_FE ≈ 160). This bias yields 15 dB power gain, 23.5 dBm P-1dB, and 33.5 dBm IP3. Thermal derating is required above T_C = 60 °C due to 150 °C/W R_thJC.

Can START499ETR be used in Class-C switching mode?

No - START499ETR is characterized and optimized for linear and Class-AB operation only. Its Gummel-Poon SPICE model and published S-parameters assume forward-active region behavior. Class-C use risks instability, excessive distortion, and junction overheating due to lack of saturation-region validation or safe operating area data.

Is the SOT-343 package compatible with standard reflow profiles?

Yes - the lead-free SOT-343 package meets JEDEC J-STD-020D moisture sensitivity level 1 and supports standard Pb-free reflow profiles (peak 260 °C, 10–30 sec). The inner box label specifies maximum soldering temperature and dwell time per JEDEC JESD97, and no special flux or underfill is required.

Does START499ETR require external matching networks?

Yes - the device is not internally matched. Application circuits in the datasheet show discrete LC networks for 50 Ω input/output matching at 1.8–2.5 GHz. S-parameters (Table 9) are provided for simulation-based matching design, and ST recommends using EM-simulated layouts to minimize parasitic effects from bond wires and pads.