What is a digital circuit? What are the characteristics of digital circuits?

To explain digital circuits, we must first explain what analog circuits are. An analog circuit is a circuit that represents the information content by the intensity of the signal (at a certain moment). For example, when a sound is converted into an electrical signal through a microphone, the magnitude of the electrical signal corresponds to the strength (voltage or current) of the electrical signal, and the circuit used to process the signal (power amplifier for short) is an analog circuit. In the transmission process, analog signals are easily disturbed and distorted (different from the original signals).

Digital circuits are different. It does not use signal strength to represent information. It represents the information of 1 or 0 by voltage or current or the on-off of the circuit, and represents some information by a series of codes of 1 or 0 (because there are only 1 and 0, it is called binary coding. The circuit used to process this signal is a digital circuit, and the information of 1 or 0 is represented by the on-off of the circuit.

Strictly speaking, digital circuits include pulse circuits and digital logic circuits. Pulse circuit mainly studies the generation, transformation and measurement of pulse. Although pulse waveforms have various shapes, they all have one thing in common, that is, the whole waveform is composed of several transient and steady-state processes. In order to obtain the transient process, the pulse circuit must include two components: one is a switch circuit, which is used to turn on and off the circuit to destroy the steady state of the circuit and establish the transient state; One is an inert circuit, which is used to control the time of transient process. The switches we use are transistors, diodes, mos tubes and their integrated circuits. Commonly used inert circuits are rc, rl, rlc and delay line, among which rc circuit is the main one.

Digital logic circuit is a science and technology that studies the coding, operation, memory, counting, storage, distribution, measurement and transmission of digital signals. Simply put, it is the science of using digital signals to realize operation, control and measurement.

Compared with analog circuits, digital circuits have the following advantages:

1. The circuit structure is simple, easy to manufacture, and convenient for integration and mass production. Low cost and convenient use,

2. The digital system composed of digital circuits works accurately and reliably with high precision.

3. It can not only complete numerical operation, but also carry out logical operation and judgment, which is indispensable in the control system. Therefore, digital circuits can also be called digital logic circuits.

This series of advantages of digital circuit over analog circuit makes it widely used in communication, automatic control, measuring instruments and computers.