## Overview of the 2SC5546 Transistor The **2SC5546** is a high-frequency NPN epitaxial planar silicon transistor. It is specifically designed for use in the driver stages of UHF (Ultra High Frequency) power amplifiers, commonly found in radio communication equipment and industrial transmitters. --- ### 1. Key Technical Specifications The following table outlines the absolute maximum ratings and primary electrical characteristics of the 2SC5546: | Parameter | Symbol | Value | Unit | | :--- | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | 30 | V | | Collector-Emitter Voltage | $V_{CEO}$ | 13.5 | V | | Emitter-Base Voltage | $V_{EBO}$ | 3.0 | V | | Collector Current | $I_C$ | 1.0 | A | | Collector Power Dissipation | $P_C$ | 10 (with heat sink) | W | | Transition Frequency | $f_T$ | ~2.5 (Typical) | GHz | --- ### 2. Physical and Structural Details * **Polarity:** NPN. * **Package Type:** Usually found in a specialized RF power package (like the **FLG** or similar surface mount/stud mount variants) designed for low thermal resistance and low parasitic inductance. * **Material:** Silicon (Si). --- ### 3. Applications and Features The 2SC5546 is optimized for performance in the UHF band (300 MHz to 3 GHz). #### Primary Features: * **High Power Gain:** Provides significant amplification even at high frequencies. * **High Efficiency:** Designed to minimize power loss as heat during high-frequency switching or amplification. * **Internal Matching:** Many RF transistors in this class include internal impedance matching to simplify the design of the surrounding circuitry. #### Common Uses: 1. **UHF Power Amplifiers:** Used in the output or driver stages of two-way radios. 2. **RF Signal Generators:** To boost signal strength in laboratory equipment. 3. **Industrial RF Heating:** In specialized high-frequency industrial controllers. --- ### 4. Circuit Implementation Example In a standard Class C amplifier configuration, the transistor would be used with a low-pass filter at the output to ensure signal purity. ```cpp // Schematic Logic Representation Input Signal -> Input Matching Network -> [2SC5546] -> Output Matching Network -> Antenna/Load | DC Bias (13.5V) ``` ---