Detailed explanation of the working principle and classification characteristics of analog-to-digital converters
Time:2024-02-28
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An analog-to-digital converter is also a type of converter. Have you ever used it? What is the function of an analog-to-digital converter? How are these functions utilized? Now let me introduce the working principle of analog-to-digital converters to you.
Working principle of analog-to-digital converter
An analog-to-digital converter, also known as an A/D converter or ADC, typically refers to an electronic component that converts an analog signal into a digital signal. A typical analog-to-digital converter is a converter that converts analog signals that have been compared with standard quantities into discrete signals represented by binary values. Therefore, any analog-to-digital converter requires a reference analog quantity as the conversion standard, and a common reference standard is the maximum convertible signal size. The output digital quantity represents the size of the input signal relative to the reference signal.
Classification of analog-to-digital converters
There are many types of analog-to-digital converters, which can be divided into indirect ADC and direct ADC according to their different working principles. 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 type ADCs. Direct ADC is directly converted into digital quantities, commonly used are parallel comparison type ADC and successive approximation type ADC.
Parallel comparison type ADC: It adopts parallel comparison of various levels, and each output code is also generated in parallel, so the conversion speed is fast. The disadvantages of parallel comparison type ADC are high cost and high power consumption.
Sequential approximation type ADC: It generates a series of comparative voltages VR, but it generates comparative voltages one by one, compares them with the input voltage step by step, and performs analog-to-digital conversion in a gradually approaching manner. It has a slower conversion speed than parallel comparison type ADCs and is much faster than double integral type ADCs, making it a medium speed ADC device.
Double integral ADC: It first integrates the input sampling voltage and reference voltage twice to obtain a time interval proportional to the average sampling voltage, while using a counter to count the standard clock pulses. Its advantages are strong anti-interference ability and good stability; The main drawback is low conversion speed.
How does an analog-to-digital converter work?
Analog to digital conversion generally involves several steps, including sampling, preservation, quantization, and encoding. Let‘s take the ∑ - △ A/D converter as an example to briefly introduce its working principle- The working principle of A/D converter is to perform signal denoising on the digital signal after the initial conversion.
Overall, the ∑ - △ A/D converter has two main parts, the analog part and the digital part. The analog part is a ∑ - △ modulator, which mainly uses oversampling technology to sample the signal and pass it through the modulator, making the quantization noise distribution wider and outputting a bit by bit data stream. The digital part is a digital filter, which denoises the digital output of the analog part, filtering out most of the quantization noise, And further quantize the output of the modulator by downscaling it to the Nyquist frequency, ultimately obtaining the output result.
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