electronic circuit
An electronic circuit is an electrical circuit that also contains active electronic devices such as transistors or vacuum tubes. They can display highly complex behaviors, even though they are governed by the same laws as simple electrical circuits. Electronic circuits can usually be categorized as analog, digital, or mixed-signal (a combination of analog and digital) electronic circuits.
Analog circuits
Analog electronic circuits are those in which electric signals vary continuously to correspond to the information being represented. Electronic equipment like voltage amplifiers, power amplifiers, tuning circuits, radios, and televisions are largely analog (with the exception of their control sections, which may be digital, especially in modern units).
The basic units of analog circuits are passive (resistors, capacitors, inductors) and active (independent power sources and dependent power sources). Components such as transistors may be represented by a model containing passive components and dependent sources. Another classification is to take impedance and independent sources and opamp as basic electronic components; this allows us to model frequency dependent negative resistors, gyrators, negative impedance converters, and dependent sources as secondary electronic components.
Digital circuits
In digital electronic circuits, electric signals take on discrete values to represent logical and numeric values that represent the information to be processed. Transistors are used primarily as switches to make logic gates. A logic gate processes signals that represent either true or false. It takes in one or more inputs and produces a single logical output. Many of the electronics produced today are digital. This is because the digital circuit has many advantages over the analog circuit. This is obvious in computers. Since computers have digital circuits, new features can be added without having to change hardware. An example of this is when a company comes out with an update for a system, you can just install it and everything works just fine. Another advantage digital has over analog is that information storage is much easier and efficient. Examples of electronic equipment which use digital circuits include digital wristwatches, calculators and PDAs, and microprocessors.
Mixed-signal circuits
Mixed-signal or hybrid circuits contain elements of both analog and digital circuits. Examples include comparators, timers, PLLs, ADCs (analog-to-digital converters), and DACs (digital-to-analog converters).
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
