What are active devices? What is a passive component? What's the difference?Release date：(2021/11/16) Number of clicks：632 |
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Simple definition of passive components: 1. If there is no power supply in electronic components when they are working, such components are called passive components. 2. From the perspective of circuit properties, passive devices have two basic characteristics: (1) Consume electric energy by itself or convert electric energy into other energy in different forms; (2) Just input the signal and work normally without external power supply. 3. Passive devices in electronic system can be divided into circuit devices and connection devices according to their circuit functions. (1) Circuit devices: diodes, resistors, resistance bars, capacitors, inductors, transformers, relays, keys, buzzers, horns, switches; (2) Connecting devices: connectors, sockets, connecting cables, printed circuit boards. Basic definition of active device: 1. If there is a power supply inside the electronic components when they are working, they are called active devices. 2. From the perspective of circuit properties, active devices have two basic characteristics: (1) It also consumes electric energy; (2) In addition to the input signal, there must be an external power supply to work normally. 3. Active devices are the main devices of electronic circuits. In terms of physical structure, circuit function and engineering parameters, active devices can be divided into discrete devices and integrated circuits. (1) Discrete devices: Bipolar crystal triode, field effect transistor, thyristor, semiconductor resistance and capacitance; (2) Analog integrated circuit devices: integrated operational amplifier, comparator, logarithmic and exponential amplifier, analog multiplier / divider, analog switching circuit, PLL circuit (phase lock loop), integrated voltage regulator, reference power supply, waveform generator and power amplifier; (3) Digital integrated circuit devices: basic logic gate, trigger, register, decoder, data comparator, driver, counter, shaping circuit, programmable logic device, microprocessor, single chip microcomputer and DSP device. Differences between active and passive components: Passive components are mainly resistance, inductance and capacitance components. Their common feature is that they can work when there is a signal without adding power in the circuit. Active components are the core of electronic circuits. All oscillation, amplification, modulation, demodulation and current conversion are inseparable from active components. The key to distinguish between active components and passive components is whether the port characteristics of the component depend on the external driving source. If yes, it is an active component and if not, it is a passive component. On the basis of consideration, ideal components are used to avoid the interference of process factors. For indivisible combined elements, if there are active devices in the composition, the whole is recognized as "active". The so-called "external characteristic" is to describe a certain relationship of the device, although the relationship is described by voltage or current, electric field or magnetic field, pressure or velocity, etc. The external characteristics of passive devices have nothing to do with whether they exist as driving sources. The concepts of passive and active are not only in electrical components, but also in mechanical, fluid, thermal, acoustic and other fields. |
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