The **2SC2757** is a silicon NPN epitaxial transistor specifically designed for high-frequency applications, primarily used as a low-noise amplifier or a local oscillator in VHF and UHF equipment. --- ### ## 1. Key Specifications The 2SC2757 is valued for its high gain-bandwidth product ($f_T$) and low noise figure. Below are the absolute maximum ratings and electrical characteristics: | Parameter | Symbol | Typical Value | Unit | | :--- | :--- | :--- | :--- | | Collector-Base Voltage | $V_{CBO}$ | 30 | V | | Collector-Emitter Voltage | $V_{CEO}$ | 15 | V | | Collector Current | $I_C$ | 50 | mA | | Collector Power Dissipation | $P_C$ | 200 | mW | | Gain-Bandwidth Product | $f_T$ | 1.1 | GHz | | Noise Figure | $NF$ | 2.5 (at 100MHz) | dB | --- ### ## 2. Physical Characteristics The 2SC2757 is almost exclusively found in the **SOT-23 (SC-59)** surface-mount package. This makes it ideal for compact RF circuit boards. **Pinout Configuration:** 1. **Base (B)** 2. **Emitter (E)** 3. **Collector (C)** --- ### ## 3. Common Applications Due to its performance in the Gigahertz range, it is commonly used in: * **VHF/UHF Tuners:** Used in older television and radio receivers. * **RF Amplifiers:** Acting as a pre-amplifier for weak signals. * **Oscillators:** Serving as the local oscillator in frequency conversion circuits. * **Mobile Communication:** Small signal processing in wireless transceivers. --- ### ## 4. Equivalent / Replacement Parts If the 2SC2757 is unavailable, the following transistors are often considered as alternatives (though pinouts and $f_T$ may vary slightly): * **2SC3356:** Higher $f_T$ (approx 7GHz), widely used in modern RF. * **BFS17:** A common European RF NPN transistor. * **BFG67:** High-frequency NPN for wideband applications. ---