### Technical Overview: 2SC5090-R The **2SC5090-R** is a high-frequency NPN epitaxial silicon transistor designed primarily for low-noise amplification and oscillation in the VHF to UHF frequency ranges. It is commonly found in telecommunications equipment, such as cellular phones and radio receivers. --- ### 1. Key Technical Specifications The "R" suffix typically refers to the **hFE (DC Current Gain)** classification, indicating a specific range of gain performance. | Parameter | Symbol | Maximum Rating | Unit | | :--- | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | 20 | V | | Collector-Emitter Voltage | $V_{CEO}$ | 12 | V | | Emitter-Base Voltage | $V_{EBO}$ | 3 | V | | Collector Current | $I_C$ | 30 | mA | | Base Current | $I_B$ | 15 | mA | | Collector Power Dissipation | $P_C$ | 150 | mW | | Junction Temperature | $T_j$ | 150 | °C | --- ### 2. RF Performance Characteristics The 2SC5090 is optimized for high-speed switching and low-noise signal processing. * **Transition Frequency ($f_T$):** Typically around **10 GHz**. This high frequency allows the transistor to operate effectively in the gigahertz range. * **Noise Figure (NF):** Extremely low, making it ideal for the first stage of a receiver (LNA - Low Noise Amplifier). * **Power Gain ($G_{pe}$):** Provides high power gain at frequencies up to 2 GHz. --- ### 3. Pin Configuration and Package The device usually comes in a small surface-mount package (e.g., **S-Mini / SOT-323**), which is essential for minimizing parasitic inductance in RF circuits. | Pin Number | Function | Description | | :--- | :--- | :--- | | 1 | **Base** | Controls the current flow between collector and emitter. | | 2 | **Emitter** | The common lead in most RF amplifier configurations. | | 3 | **Collector** | The output terminal for the amplified signal. | --- ### 4. Common Applications * **LNA (Low Noise Amplifiers):** Used in the front-end of GPS, cellular, and Wi-Fi receivers. * **VCO (Voltage Controlled Oscillators):** Used in local oscillators for frequency synthesis. * **RF Mixers:** Helping to convert high-frequency signals to lower intermediate frequencies. --- ### 5. Classification (hFE Rank) The "R" marking identifies the DC current gain range: * **R Rank:** Typically **80 to 160** $h_{FE}$. * **O Rank:** Typically **50 to 100** $h_{FE}$.