The UN421E is a silicon epitaxial planar type NPN transistor manufactured by Panasonic. It's designed for low-noise amplification in various electronic circuits.

Applications

• Low-noise amplifier circuits
• Microphone preamplifiers
• Audio frequency amplifiers
• Sensor signal amplification
• Communication equipment

Features

• Low Noise Figure: Ensures minimal noise addition to the signal.
• High Current Gain (hFE): Provides effective signal amplification.
• Low Collector-Emitter Saturation Voltage: Allows efficient switching and amplification.
• Small Package Size: Enables compact circuit designs.
• High Transition Frequency: Suitable for high-frequency applications.

Benefits

• Improved Signal Clarity: Low noise figure ensures a clean amplified signal.
• Efficient Amplification: High current gain provides significant signal amplification.
• Reduced Power Consumption: Low saturation voltage minimizes power loss.
• Compact Circuit Design: Small package allows for high-density component placement.
• Versatile Use: Suitable for a wide range of low-noise amplification applications.

Additional Details

The UN421E has a collector-emitter voltage (VCEO) rating of 50V, a collector current (IC) rating of 150mA, and a power dissipation (PC) rating of 200mW. Its noise figure (NF) is typically around 1 dB, making it suitable for sensitive low-noise applications. The transistor's hFE ranges typically from 200 to 700, ensuring ample signal amplification. It is available in a small surface-mount package (e.g., SOT-346 or similar). The transition frequency (fT) is around 250 MHz, which makes it useful in high-frequency applications.

When using the UN421E, proper biasing is essential to maintain stable and linear amplification. Shielding of the circuit can further reduce noise. Datasheet specifications should be carefully consulted to ensure that the transistor operates within its safe operating area. The transistor's low noise characteristics make it particularly valuable in applications where preserving signal integrity is critical, such as in audio preamplifiers and sensor signal conditioners.