Infineon BFS17PE6327HTSA1 NPN Silicon RF Transistor: Datasheet, Pinout, and Application Circuit Design

The Infineon BFS17PE6327HTSA1 is a high-performance NPN silicon RF transistor engineered for small-signal amplification in high-frequency applications. Packaged in the ultra-compact SOT-23, this device is a cornerstone in modern RF design, offering excellent gain, low noise, and robust performance in a minimal footprint. It is specifically designed for use in VHF to microwave frequency ranges, making it ideal for applications such as mobile radio, satellite communication, wireless infrastructure, and other RF systems requiring stable amplification.

Datasheet Overview and Key Specifications

A thorough review of the datasheet is critical for successful implementation. The BFS17PE6327HTSA1 operates effectively within a collector-emitter voltage (`V_CE`) of 15V and a collector current (`I_C`) of 30 mA. Its standout feature is its transition frequency (f_T) of 8 GHz, which defines its upper frequency limit for useful current gain. Key parameters include:

Gain Performance: A typical |S21|² of 18 dB at 900 MHz and 4.5 V, 10 mA.

Noise Figure: A low noise figure of 1.4 dB at 900 MHz ensures minimal signal degradation in sensitive receiver front-ends.

Power Dissipation: The device has a total power dissipation of 330 mW, which must be considered for thermal management.

Pinout Configuration (SOT-23 Package)

Correctly identifying the pinout is essential for PCB layout. The SOT-23 package has three pins:

1. Pin 1 (Emitter): This pin is typically connected to the ground reference in common-emitter amplifier configurations.

2. Pin 2 (Base): This is the input pin for the RF signal to be amplified. It requires a carefully biased DC voltage and often includes an impedance matching network.

3. Pin 3 (Collector): This is the output pin, which delivers the amplified signal. It is connected to the load via a DC-blocking capacitor and is supplied with the collector voltage through a bias resistor or RF choke.

Application Circuit Design: A 900 MHz Common-Emitter Amplifier

A fundamental application for the BFS17PE6327HTSA1 is a common-emitter small-signal amplifier. The design focuses on providing stable DC bias and ensuring proper RF impedance matching at the input and output.

1. DC Biasing Network:

The goal is to set a quiescent point (Q-point) for stable operation, typically around `V_CE = 4.5V` and `I_C = 10 mA`. This is achieved using a voltage divider network at the base (R1 and R2) and an emitter resistor (R_E) for stability. A bypass capacitor (C_E) is placed in parallel with R_E to ground it at RF frequencies, preventing negative AC feedback and preserving gain.

2. RF Impedance Matching:

For maximum power transfer, the input and output impedances of the transistor must be matched to the source and load impedances (typically 50 Ω). This is accomplished using matching networks, often consisting of series inductors (L1, L3) and shunt capacitors (C2, C4). These networks also serve to isolate the DC bias from the RF signal paths.

3. Signal Coupling and Decoupling:

DC-blocking capacitors (C1, C5) are placed at the input and output to prevent DC voltages from affecting the source and load. An RF choke (L2) is used on the collector bias line to present a high impedance to the RF signal, preventing it from leaking into the power supply.

Design Considerations:

Stability: Ensure the amplifier is unconditionally stable across the desired frequency band by analyzing the Rollett stability factor (K-factor) from the S-parameters provided in the datasheet.

Layout: RF circuit performance is heavily dependent on PCB layout. Use a continuous ground plane, keep RF traces short and direct, and utilize appropriate decoupling capacitors near the supply pins.

ICGOOODFIND

The Infineon BFS17PE6327HTSA1 stands out as a highly reliable and efficient solution for low-noise amplification in the RF spectrum. Its combination of high gain, low noise figure, and compact SOT-23 packaging makes it an excellent choice for designers working on space-constrained, high-frequency applications. A deep understanding of its datasheet parameters, correct pinout connection, and meticulous attention to biasing and impedance matching in the circuit design are paramount to unlocking its full performance potential.

Keywords: RF Transistor, S-Parameters, Impedance Matching, Low Noise Amplifier (LNA), SOT-23 Package.