SMA4021

The SMA4021 is a dual-channel high-gain Bipolar Junction Array (BJT) intended for audio and video applications. It is manufactured by San Microelectronics, a well-known semiconductor company that designs, develops, and manufactures high-performance operational amplifiers, filters, and transistors for various applications.

The SMA4021 is a gain array designed for audio and video applications. It consists of two high-gain Darlington transistors with each transistor having an emitter-coupled collector. Each transistor has a common emitter and the collector terminals are coupled directly together. This configuration provides a gain of up to 8,000 times. The collector-base junction of each transistor is biased at the same voltage, allowing for symmetric operation of the transistors.

The SMA4021 is ideal for use in preamplifiers, amplifiers, equalizers, mixers and audio/video applications requiring high gain and low noise levels. Its low output impedance and high open-loop gain allows for accurate signal reproduction at low levels. Additionally, its high gain and low noise levels are well-suited for applications such as audio mixing, video switching, and audio/video summing.

In use, the SMA4021 is connected to a power supply, usually either a single-ended or balanced DC power supply, which provides the necessary voltage for operation. Connections for the audio inputs and outputs of the device are then made. The SMA4021 can then be used to amplify low-level audio signals, with higher output levels achievable with the addition of multiple gain stages.

When it comes to the working principle of the SMA4021, the transistors within the array act as amplifiers, each transistor amplifying the input signal by applying voltage to the emitter. This emitter voltage is connected to the common base terminal, while the collectors are connected directly to the input source. As the input voltage increases, the output voltage also increases, thus amplifying the input signal. This gain is determined by the voltage applied to the emitter, which is in turn determined by the current flowing through it, as well as the gain of the individual transistors.

Overall, the SMA4021 is a high-gain, low-noise Bipolar Junction Array designed for audio and video applications. It is capable of providing high gains and low noise levels, making it ideal for applications such as audio mixing and video switching. Its low output impedance and high open-loop gain also make it ideal for accurate signal reproduction, even at low levels.