Active devices, passive devices, "source" refers to the "drive source" or "curated source", only this "source "for electronic devices often from the" power "so there is a misuse, said "misuse" because the technical language must be rigorous, the source is not equal to the power, as the voltage source, current source can not simply be called power reason The same. In English, active device and passive device are Active Device and Passive Device respectively, which do not generate ambiguity in themselves, and there is no corresponding original context in Chinese, while the principle of translating foreign languages, especially the classical principle, is to try to use local near-sense words to carry out a certain meaning or specific reference to things through connotation constraints or redefinition, which often gives rise to meaning, and sometimes it is really necessary to to standardize the concept by reading the original text.

The key to distinguish between active and passive devices is whether the port characteristics of the component depends on the external source of currents, yes, it is an active device, non-passive devices, the basis for consideration of ideal components to avoid the interference of process factors. For the inseparable combination of components, if there are active devices in the composition, the whole is considered as "active".

For an ideal resistor or resistor network, its VA characteristics do not change with external currents, and even without external currents its characteristics still hold, so it is independent of external currents, so the resistor is a passive device.

For an ideal crystal transistor, its characteristic Ic=BIb to be established must be given a specific curation, otherwise it can not be established (such as reverse bias CE junction voltage), so its characteristics are subject to external curation, so the crystal transistor is an active device.

For an ideal crystal diode, considering its port characteristics alone, it is also obviously independent of external curation, as a matter of fact, should be passive devices, but there are many types of diodes, such as the electro-optical characteristics of LEDs, photodiodes, the relationship between the reverse conductivity and the incident light intensity characteristics, etc., when considering these characteristics can not be replaced by a simple ideal diode model, the external curation source in this is a necessary condition (Note that the source is not just an electrical "source"), coupled with the complexity of the diode application, the diode is generally classified as an active device, but the ideal diode is still a passive device, which is a special place, I personally hold this view.

In electronics is the following classification.
1, passive devices (passive devices, active components), also called linear components, in the circuit of the electrical characteristics of a straight line.
2, active devices (active devices, active components), also known as linear components, in the electrical characteristics of the circuit is not a straight line.
When analyzing the functions and technical parameters of electronic circuits, electronic components are generally divided into two categories: passive and active devices.

1. A simple definition of passive devices
If an electronic component operates without any form of power source inside it, the device is called passive.
By the nature of the circuit, passive devices have two basic characteristics.
(1) Self or consume electrical energy, or convert electrical energy into other energy in different forms.
(2) Only the input signal is required, and no external power supply is needed for proper operation.

2. Basic definition of active devices
If an electronic component operates with a power source present inside it, the device is called an active device.
By the nature of the circuit, active devices have two basic characteristics.
(1) It also consumes electricity itself.
(2) In addition to the input signal, there must be an external power supply for proper operation.
It can be seen that active and passive devices require completely different operating conditions and ways of working in the circuit, which must be paid much attention to in the learning process of electronics technology.

1 Common passive electronic devices
Passive devices in electronic systems can be divided into circuit-based devices and connection-based devices according to the circuit function they perform.
1. Circuit-type devices
(1) Diode
(2) Resistor
(3) Resistor network
(4) Capacitor
(5) Inductor
(6) Transformer
(7) Relay
(8) Key(key)
(9) Buzzer, horn (speaker)
(10) Switch

2. Connection type devices
(1) Connector
(2) Socket (shoket)
(3) Connection cable (line)
(4) Printed Circuit Board (PCB)

2 Common active electronic devices
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 two categories: discrete devices and integrated circuits.
1. discrete devices
(1) Bipolar transistor (bipolar transistor), generally referred to as a triode, BJT
(2) Field-effect transistor (field effective transistor)
(3) Thyristor (thyristor), also known as silicon controlled
(4) Semiconductor resistors and capacitors - Resistors and capacitors manufactured with integrated technology and used in integrated circuits.

2. Analog integrated circuit devices
Analog integrated circuit devices are integrated circuit devices that are used to process analog voltage or current signals that vary continuously over time.
Basic analog integrated circuit devices generally include.
(1) Integrated operational amplifier (op amp), referred to as integrated op amp
(2) Comparator
(3) Logarithmic and exponential amplifiers
(4) Analog multiplier/divider
(5) Analog switch circuit
(6) PLL circuit (phase lock loop), i.e., phase-locked loop circuit
(7) Integrated voltage regulator (voltage regulator)
(8) Reference power supply (reference source)
(9) Wave-form generator
(10) Power amplifier

3. Digital integrated circuit devices
(1) Basic logic gate circuit
(2) Trigger (flip-flop)
(3) Register
(4) Decoder
(5) Data comparator (comparator)
(6) Driver
(7) Counter
(8) Rectification circuit
(9) Programmable Logic Devices (PLD)
(10) Microprocessor (MPU)
(11) Microcontroller (MCU)
(12) DSP devices (Digital signal processor, DSP)