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What is the difference between active devices and passive devices
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What is the difference between active devices and passive devices
What is an active device

What is an active device? Active components are the core of electronic circuits. All oscillation, amplification, modulation, demodulation, and current conversion are inseparable from active components. 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, an external power supply is also required to work normally. It can be seen that active devices and passive devices have completely different requirements for the working conditions and working methods of the circuit, which must be paid attention to in the learning process of electronic technology.

Common active electronic devices

Discrete devices: field effective transistors, thyristors, also called thyristors, bipolar transistors, generally referred to as triodes, BJTs, semiconductor resistors and capacitors-manufactured by integrated technology Resistors and capacitors are used in integrated circuits.

Analog integrated circuit devices: comparator (comparator), analog multiplier/divider (multiplier/divider), integrated operational amplifier (operation amplifier), referred to as integrated operational amplifier, logarithmic and exponential amplifier, PLL circuit (phase lock loop), namely Phase-locked loop circuit, analog switch circuit (analog switch), reference source (reference source), power amplifier (power amplifier), waveform generator (wave-form generator).

Passive components

The definition of passive devices is as follows: passive devices are used for signal transmission, or "signal amplification" through directivity. Capacitors, resistances, and inductors are all passive devices, and ICs and modules are all active devices. 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 to the circuit.

Passive components

Capacitance: The letter code of the capacitor is C. The unit of capacitance is Farad (denoted as F), commonly used as μF (micro method), PF (ie, μ μF, pico method). Capacitors are also one of the most common components in electronic circuits. It is a component that stores electrical energy. The capacitor is composed of two conductors of the same size with a layer of insulating medium between them. When voltage is applied across it, the capacitor

Charge will be stored on it. Once there is no voltage, as long as there is a closed loop, it will release electrical energy. Capacitors prevent DC from passing in the circuit, but allow AC to pass. The higher the frequency of AC, the stronger the ability to pass. The characteristics of the capacitor in the circuit are non-linear. The impedance to current is called capacitive reactance. The capacitive reactance is inversely proportional to the capacitance and the frequency of the signal.

Resistance: The symbol of resistance in the circuit diagram is the letter R. The standard unit of resistance is ohm, denoted as R. Also commonly used are kiloohm KΩ and megaohm MΩ. When current flows through a conductor, the property of the conductor's internal resistance to block the current is called resistance. The components that block the current in the circuit are called resistors, or resistors for short. The main purpose of resistors is to step down, divide voltage or shunt, and are used as load, feedback, coupling, isolation, etc. in some special circuits.

Inductance: Inductance is a typical component of electromagnetic induction and electromagnetic conversion. The most common application is transformer. Inductance, like capacitance, is also an energy storage component. Inductors are generally made of coils. When an alternating voltage is applied to both ends of the coil, an induced electromotive force is generated in the coil, which prevents the current passing through the coil from changing. This hindrance is called inductive resistance. The inductance is proportional to the inductance and the frequency of the signal. It does not hinder direct current (the DC resistance of the coil is not counted). Therefore, the role of inductance in electronic circuits is: blocking, voltage transformation, coupling and cooperating with capacitors for tuning, filtering, frequency selection, frequency division and so on.

The difference between active devices and passive devices

After understanding the definition of active devices and passive devices, let's take a look at the difference between the two.

In electronics, circuits containing transistor components are usually referred to as "active circuits" (such as active speakers, active filters, etc.), while circuits consisting only of RC components are referred to as "passive circuits". A device that can independently exhibit its external characteristics without relying on the existence of an external power source (DC or AC) is a passive device. Outside are active devices. The so-called "external characteristics" is to describe a certain relationship of the device, although it uses voltage or current, electric 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.

The difference between active devices and passive devices

A device that can independently exhibit its external characteristics without relying on the existence of an external power source (DC or AC) is a passive device. Outside are active devices. The so-called "external characteristics" is to describe a certain relationship of the device, although it uses voltage or current, electric or magnetic field pressure or speed to describe its relationship.iPCB has passed ISO9001:2008, ISO14001, UL, CQC and other quality management system certifications, produces standardized and qualified PCB products, masters complex process technology, and uses professional equipment such as AOI and Flying Probe to control production and X-ray inspection machines. Finally, we will use double FQC inspection of appearance to ensure shipment under IPC II standard or IPC III standard.