In order to help you know more about passive devices and active devices, below, I will share common passive devices and active devices and their differences, hoping to help you!
Basic definition of active devices
If an electronic component has an internal power supply when working, it is called an active device.
As far as circuit characteristics are concerned, active devices have two basic characteristics:
(1) itself consumes electricity.
(2) In addition to the input signal, there must be an external power supply to work normally.
It can be seen that active devices and passive devices have completely different requirements for the working conditions and working modes of circuits, which must be paid great attention to in the learning process of electronic technology.
Simple definition of passive devices
If an electronic component works without any form of power supply inside, it is called a passive device.
From the circuit nature, passive devices have two basic characteristics:
(1) It either consumes electric energy or converts it into other energy in different forms.
(2) It can work normally only by inputting signals and without external power supply.
Common active electronic devices
Active devices are the main devices in electronic circuits. From the physical structure, circuit function and engineering parameters, active devices can be divided into two categories: discrete devices and integrated circuits.
1. discrete device
(1) bipolar transistor, commonly known as triode, bjt.
(2) field effect transistor.
(3) Thyristors, also called silicon controlled rectifiers.
(4) Semiconductor resistance and capacitance? Resistors and capacitors manufactured by integrated technology in integrated circuits.
2. Analog integrated circuit devices
Analog integrated circuit devices are integrated circuit devices used to process analog voltage or current signals that change continuously with time.
Basic analog integrated circuit devices usually include:
(1) integrated operational amplifier.
(2) Comparator
(3) Logarithmic and exponential amplifier
(4) Analog Multiplier/Divider
(5) Analog switch circuit
(6) pll circuit (phase locked loop), that is, phase locked loop circuit.
(7) Integrated voltage regulator
(8) Reference sources
(9) Waveform generator
(10) power amplifier
3. Digital integrated circuit devices
(1) basic logic gate circuit
(2) Trigger
(3) Registration
(4) Decoder
(5) Data comparator
6. Drivers
(7) Counter
(8) shaping circuit
(9) Programmable logic devices
(10) microprocessor
(1 1) microcontroller
(12) digital signal processor (dsp)
Common. Passive electronic equipment
Passive devices in electronic systems can be divided into circuit devices and connecting devices according to their circuit functions.
1. Circuit equipment
(1) diode
(2) resistor
(3) Resistance network
(4) Capacitor
(5) sensor
(6) Transformer
(7) relay
(8) keys
(9) Buzzer and speaker
(10) switch
2. Connected devices
(1) connector
(2) shoket
(3) Connecting cables (wires)
(4) Printed circuit board
Passive components are mainly resistive, inductive and capacitive components, which are unique in that they can work when there is a signal without adding power to the circuit.
1. Resistance
When current passes through a conductor, the property that the internal resistance of the conductor hinders the current is called resistance. The elements that block the current in the circuit are called resistors, or resistors for short. The main function of resistor is to reduce voltage, divide voltage or shunt current, and it is used as load, feedback, coupling and isolation in some special circuits.
The symbol of resistance in the circuit diagram is the letter R, and the standard unit of resistance is ohm, which is recorded as R. How many thousands of ohms are commonly used? Megaohm m? .
IK？ = 1000? 1M？ = 1000K？
2. Capacitance
Capacitance is also one of the most common components in electronic circuits. It is an element for storing electric energy. A capacitor consists of two conductors with the same size and homogeneity, with a layer of insulating medium sandwiched between them. When a voltage is applied to the capacitor, the capacitor will store charge. Once there is no voltage, as long as there is a closed loop, it will be discharged again. Capacitors prevent DC from passing through the circuit, but allow AC to pass through. The higher the frequency of alternating current, the stronger the passing capacity. Therefore, capacitors are usually used in coupling, bypass filtering, feedback, timing and oscillation circuits.
The letter code of the capacitor is C, and the unit of the capacitor is Farah (F). F (micro-machining), PF (i.e.? F, microfabrication).
1F= 1000000？ F 1？ F= 1000000PF
The characteristics of capacitance in the circuit are nonlinear. The impedance to current is called capacitive reactance. Capacitance is inversely proportional to capacitance and signal frequency.
3. Inductance coefficient
Inductor, like capacitor, is also an energy storage element. Inductors are generally made of coils. When AC voltage is applied across the coil, induced electromotive force will be generated in the coil, thus preventing the current passing through the coil from changing. This obstacle is called inductive reactance. Inductance is proportional to inductance and signal frequency. Do not hinder DC (regardless of the DC resistance of the coil). Therefore, the functions of inductance in electronic circuits are: blocking current, transforming voltage, coupling and matching capacitance for tuning, filtering, frequency selection, frequency division and so on.
The code name of inductance in the circuit is L, and the unit of inductance is Henry (recorded as H). Commonly used are milli-Heng (mH) and micro-Heng (? h).
1H = 1000 MH 1mH = 1000？ H
Inductor is a typical component of electromagnetic induction and electromagnetic conversion, and the most common application is transformer.
active device
Active components are the core of electronic circuits, and all oscillation, amplification, modulation, demodulation and current conversion are inseparable from active components.
Electron tube, also known as vacuum tube, also known as electric vacuum device.
An electron tube, whether bipolar or multipolar, has an anode and a cathode, and the cathode emits electrons to the anode under the action of an external power supply. The external power supply can be directly applied to the cathode or another heating wire. It is because of this external power supply that they are collectively called active devices.
Electron tube is the earliest active electronic component, which is divided into diode, triode and multipole. With the development of electronic technology, electron tubes have given way to transistors and integrated circuits because of their large size, heavy weight and high power consumption. However, in many occasions, electron tubes continue to play a role, and devices that can independently display their external characteristics without the existence of external power supply (DC or AC) are passive devices. In addition, there are active devices.
So-called? External characteristics? It is a relative quantity that describes the device, although it uses voltage or current, electric field or magnetic field pressure or speed to describe its relationship.
The external characteristics of passive devices have nothing to do with whether they exist as driving sources or not.
The concepts of passive and active exist not only in electrical components, but also in mechanical, fluid, thermal, acoustic and other fields.
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