Active components are key components in electronic circuits that can actively control current, voltage, or perform data operations, processing, and other functions. They usually require an external power supply to increase energy to generate energy gain in the circuit or control the flow of signals.
Common active component classification:
1. Transistor
① Bipolar transistor (BJT): BJT has two PN junctions and can amplify current and voltage signals. They are widely used in analog circuits and digital circuits, such as amplifiers, switching circuits, etc. The amplification of BJT is based on the injection and recombination process of carriers (electrons and holes)
② Field effect transistor (FET): FET controls the output current by changing the width of the conductive channel by controlling the input voltage. FET has the advantages of high input impedance, low noise, and low power consumption, and is particularly suitable for high-frequency circuits and integrated circuits. Common FET types include MOSFET (metal oxide semiconductor field effect transistor) and JET (junction field effect transistor)
③ Insulated gate bipolar transistor (IGBT): IGBT combines the advantages of BJT and MOSFET, with high input impedance, low on-state voltage drop, and fast switching speed. Widely used in the field of power electronics, such as frequency converters, inverters, etc., to control the operation of high-power power equipment
2. Integrated circuits
① Operational amplifier: a high-gain analog circuit that can amplify weak signals and is used in signal filtering, analog calculation and other fields. It is one of the core components in analog circuits and is widely used in various measurement, control and signal processing systems
② Digital integrated circuits: including various logic gate circuits (such as AND gates, OR gates, NOT gates, etc.), triggers, counters, memories, etc. These integrated circuits can realize complex digital logic operations and data processing functions and are the cornerstone of modern digital electronic systems
③Microcontrollers (MCU) and programmable logic controllers (PLC): These are complex integrated circuits that integrate functions such as CPU, memory, input and output interfaces. They can execute program instructions and realize functions such as automatic control and data processing. They are widely used in industrial automation, smart homes, automotive electronics and other fields
Special function category
① Voltage reference category: active components that provide stable output voltage, commonly used as voltage references for analog and digital circuits. Common voltage reference sources include Zener diodes, voltage reference integrated circuits, etc. They can ensure that the voltage signal in the circuit is stable and reliable
② Active components that can generate stable oscillation signals are widely used in communications, broadcasting, timing and other fields. There are many types of oscillators, including RC oscillators, LC oscillators, quartz crystal oscillators, etc. They can generate stable periodic signals to provide clock sources or signal sources for circuits
③ Power management components: such as voltage monitors, current monitors, power switches, etc. These components are used to monitor and manage the power supply system to achieve power supply stabilization, switching, protection and other functions. They can ensure that the power supply in the circuit is stable and reliable, and prevent circuit failures or damage caused by power problems
Application areas of active components:
Active components play a vital role in electronic equipment and systems. They can perform active functions such as signal amplification, conversion, control and data processing. Therefore, the application field of the device is very wide:
1. Communication equipment
① Power amplification: Active components such as field effect tubes are widely used in communication equipment for power amplification to ensure that the signal maintains sufficient strength and stability during transmission
② Signal processing: Integrated circuits (ICs) are the core components of communication equipment, responsible for processing complex signals and data, and realizing functions such as communication protocol conversion and encryption and decryption
2. Computer system
① Central processing unit (CPU): It is the heart of the computer, composed of a large number of integrated circuits, responsible for executing instructions, processing data and controlling the operation of the computer system
② Memory and storage devices: Active components such as dynamic random access memory (DRAM) are used to store temporary data, while storage devices such as flash memory are used to store data for a long time
3. Consumer electronics
① TVs and monitors: Active components such as image tubes and liquid crystal displays are important components of TVs and monitors, responsible for displaying images and videos
② Audio equipment: Active components such as transistors are used in audio equipment to amplify sound signals to ensure clear sound quality and moderate volume
4. Industrial automation
① Control systems: Active components play a key role in industrial automation control systems. For example, sensors are used to detect physical quantities and convert them into processable electrical signals, and controllers perform corresponding control operations based on these signals.
② Motor drive: Active components such as thyristor rectifiers are used to drive motors to achieve precise speed and torque control
5. Medical equipment
① Medical imaging equipment: Active components such as image tubes in medical equipment such as X-ray machines and CT scanners are used to produce and display images of the human body
② Vital sign monitoring: Active components such as sensors are used to monitor patients' vital signs, such as heart rate, blood pressure, etc., and transmit data to medical personnel for analysis and processing
6. Aerospace
① Navigation and communication systems: Active components such as integrated circuits are widely used in navigation and communication systems in the aerospace field to ensure accurate navigation of aircraft and real-time communication with the ground
② Control systems: Complex control systems rely on a large number of active components to achieve precise control of the posture, speed and trajectory of flying chess
