Analog signals and digital signals have different characteristics, and the methods and circuits for processing these two types of signals are also different. Generally speaking, electronic circuits can be divided into two main categories: analog circuits and digital circuits.
1. Analog circuits
Electronic circuits that process analog signals are called analog circuits. The focus of analog circuit research is on the waveform changes of signals during processing and the influence of devices and circuits on the signal waveform, mainly using circuit analysis methods.
2. Digital circuits
Electronic circuits that process digital signals are called digital circuits. Digital circuits focus on the logical relationships between the inputs and outputs of various circuits, and often utilize methods such as Boolean algebra, truth tables, Karnaugh maps, and state transition diagrams in their analysis.
The analysis methods for analog and digital circuits differ significantly, which is determined by the different characteristics of analog and digital signals. Since electronic circuits are divided into analog and digital circuits, electronic technology is often categorized into analog electronics and digital electronics. However, these two technologies are not isolated; in many cases, both analog and digital technologies are used in combination.
However, with the continuous development of electronic technology, digital circuits are being used more and more widely, replacing analog circuits in many fields. The main reason for this is:
① Digital circuits are easier to program using various algorithms, making their applications more flexible;
② Digital circuits can provide higher operating speeds;
③ By using digital circuits, the range of digital information can be wider and the representation accuracy can be higher;
④ Digital circuits can employ embedded error correction systems.
⑤ Digital circuits are easier to miniaturize than analog circuits, etc.
In circuit research, the terms linear circuit and nonlinear circuit are frequently encountered. A circuit composed of a power source and linear components is a linear circuit. A linear component is one whose parameters are independent of electrical quantities such as voltage and current; a linear circuit can be described by linear equations. A circuit whose characteristics cannot be described by linear equations is called a nonlinear circuit; most circuits containing electronic devices are nonlinear circuits.
