The circuit that converts analog signals into digital signals is called an analog-to-digital converter (ADC). The function of A/D conversion is to convert analog signals with continuous time and amplitude into digital signals with discrete time and amplitude. Therefore, A/D conversion generally requires four processes: sampling, holding, quantization, and encoding. In practical circuits, some of these processes are combined, such as sampling and holding, quantization, and encoding, which are often implemented simultaneously during the conversion process
The basic principle of this converter is to sample the input analog signal at specified time intervals and compare it with a series of standard digital signals. The digital signal gradually converges until the two signals are equal. Then display the binary number representing this signal. There are many types of analog-to-digital converters, such as direct, indirect, high-speed, high-precision, ultra high speed, etc. Each has many forms. The function opposite to that of an analog-to-digital converter is called a "digital to analog converter", also known as a "decoder". It is a device that converts digital quantities into continuously changing analog quantities, and there are also many types and forms
Indirect ADC first converts the input analog voltage into time or frequency, and then converts these intermediate quantities into digital quantities. Commonly used are double integral ADCs with intermediate quantities of time.
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