Analog circuits and digital circuits are one way of classifying electronic circuits. The concept of analog versus digital is a very important concept discussed in physics, engineering, electronics, computing, instrumentation, mathematics and various other fields. In this article, we are going to discuss what analog circuits and digital circuits are, and the difference between analog circuits and digital circuits.

What is Analog Circuits?

Most of the entities we encounter in our daily lives are analog entities. An analog circuit is a circuit that manipulates or operates on analog data. In physics, as well as electronics, analog is a term used to describe a signal or a function which can take any value over a given region. An analog signal is continuous. A sinusoidal voltage signal is a very good example for an analog signal. An analog signal has infinitely many values between any two given values. This is, however, limited by the capabilities and the resolution of the instruments used to measure these signals.

Analog signals can be detected and analyzed using instruments such as cathode ray oscilloscopes, voltmeters, ammeters and other recording devices. If an analog signal has to be analyzed using a computer, it has to be converted into a digital signal. This is because computers are only capable of handling digital signals. Analog computing can be done using devices such as operational amplifiers and transistors.

What is Digital Circuits?

The term “digital” is derived from the word “digit” which means a specific number. A digital circuit is a circuit that handles and operates on digital data. Even though a digital circuit operates on digital data, the components are based on analog electronics. A digital signal can take only discrete values. For example, the logic levels of 1 and 0 are digital values. A logic level between 1 and 0 or “true” and “false” doesn’t exist. If a digital signal is digitized with values very close to each other and with a large number of values, it can be said that the signal is a fine approximation for the corresponding analog signal.

Computers use digital signals in their internal circuits but most of the other equipment use analog signals. The least resolved digital signal has two discrete values. The real voltage of these depends on the physical circuits used. These two leveled signals are known as binary signals. A decimal signal has 10 voltage levels, and a hexadecimal signal has 16 voltage levels. The analog circuit responsible for handling digital data is produced so that a range over the exact digital value is detected as the analog value itself. This is due to errors of the signal and deformation by components.

What is the difference between Analog Circuits and Digital Circuits

Analog Circuits	Digital Circuits
These circuits operate on continuous valued signals(commonly referred to as analog signals).	These circuits operate on signals that exist only at two levels i.e. 0's and 1's (binary number system).
Analog circuits are difficult to design since each component has to be placed by hand as automation techniques for designing these circuits fail to do the job efficiently.	On the other hand digital circuits are easy to design since automation technique can be applied at various levels of circuit design. This involves minimum human interaction.
No conversion of input signals are required before processing i.e. input signal is analog, the circuit directly performs various logical operations and produces an analog output.	In digital circuits, the input signals are converted from analog to digital form before it is processed, i.e. the digital circuit is capable of processing digital signals only, and produces output which is again converted back from digital to analog signals so that the output gives meaning full results that can be understood by humans.
In analog circuits, since there are no conversions involved at the input or at the output side there is no loss of information that is available for processing.	Due to the conversion process at the input side(analog to digital) and at the output side, some amount of information is lost during the conversion process.
The man power available to design analog circuits is very low, this results in long time to market the finished products.	The available man power to design digital circuits is significantly large compared to that of analog circuit designers.
Analog circuits are mostly custom made and lacks flexibility.	Digital circuits have high degree of flexibility.