What are the main technical indicators of adc converters?
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What are the main technical indicators of adc converters?

Posted Date: 2024-01-27

What are the main technical indicators of adc converters?

The main technical indicators of ADC (analog-to-digital converter) are as follows:

1. Resolution: Resolution refers to how many discrete digital values ​​the ADC can divide the analog input signal into. Expressed as a number of bits (bits), for example, a 12-bit resolution ADC can divide the analog input signal into 2^12=4096 discrete digital values.

2. Sampling Rate: The sampling rate refers to the number of times the ADC samples the analog input signal per second. Expressed in Hertz (Hz), for example an ADC with a sampling rate of 1kHz samples the analog input signal 1000 times per second.

3. Accuracy: Accuracy refers to the error between the digital value of the ADC output and the true value of the analog input signal. Accuracy is usually expressed as a percentage or in some fixed unit, such as 1% accuracy or 10 millivolt accuracy.

4. Gain Error: Gain error refers to the difference between the gain of the ADC and the ideal gain. Gain error causes a difference between the digitized value of the ADC output and the actual value of the analog input signal.

5. Nonlinearity Error: Nonlinearity error refers to the nonlinear relationship between the digital value output by the ADC and the analog input signal. Nonlinear errors can cause the ADC to output a large difference between the digitized value and the analog input signal under certain circumstances.

6. Signal-to-Noise Ratio (SNR): The signal-to-noise ratio describes the relationship between the digital signal output by the ADC and the noise present in the signal. A higher signal-to-noise ratio means that the ADC is able to effectively separate the signal from the noise.

Four processes of adc converter

The device that converts analog to digital is usually called an analog-to-digital converter (ADC), or A/D for short. Normally, A/D conversion generally goes through four processes: sampling, holding, quantization and encoding.

1. Sampling: Sampling refers to discretizing analog signals in time and converting continuous analog signals into discrete samples. During the sampling process, the analog input signal will be sampled by the sampler as a series of analog values ​​at discrete time points according to a certain time interval.

2. Hold: Hold is to keep the signal at a fixed voltage after sampling so that it can be quantized and encoded later. The hold circuit is used to keep the level of the sampled analog signal stable during the next sampling period.

3. Quantization: Quantization is the conversion of continuous analog signals into discrete digital values. During quantization, the amplitude of the sampled signal is mapped onto a series of discrete numerical levels. The common approach is to divide the analog signal into a fixed number of equally spaced intervals and map the sampled values ​​to the closest digitized value.

4. Encoding: Encoding is to convert the quantized digital signal into binary form to facilitate transmission, processing and storage. Encoding can use different encoding methods, such as two's complement, binary one's complement, etc. The encoding process assigns the quantized value a specific binary code to represent the value.

These four processes are the key steps in A/D conversion. Through these steps, continuous analog signals can be converted into discrete digital data to facilitate the processing and processing of digital systems.

What types and functions do adc converters have?

ADCs (Analog-to-Digital Converters) come in many types and functions, some of the common ones include:

1. Successive approximation ADC: The successive approximation ADC is a converter based on bit-by-bit comparison. It approaches the value of the input analog signal bit by bit to obtain a digital output. Successive approximation ADCs are slower but have higher accuracy.

2. Latch-type ADC: The latch-type ADC is a converter based on a comparator and a latch circuit. It uses a high-speed comparator to perform a large number of comparison operations, and the latch circuit locks the digital output in a timely manner. Latch-up ADCs are suitable for high-speed data acquisition applications.

3. Parallel ADC: A parallel ADC is a converter that divides an analog signal into multiple sub-signals and converts them simultaneously. Due to parallel conversion, it has a higher sampling rate and lower latency, making it suitable for applications that require large amounts of data to be converted simultaneously.

4. Feedback ADC: Feedback ADC is a converter that uses analog feedback technology to improve accuracy. It uses feedback circuits to reduce quantization errors and improves the accuracy of conversion through multiple sampling and iterative calculations.

5. Analog front-end functions: Some ADCs also have built-in analog front-end functions, such as analog gain amplifiers (PGA), filters, and automatic gain control (AGC). These functions can process, enhance and optimize input signals to suit different application needs.

6. Reference voltage: ADC usually requires a reference voltage to determine the range and accuracy of conversion. Some ADCs can use an externally provided reference voltage, while others may have an internally integrated reference voltage source and support different reference voltage options.

These are some common types and functions of ADC. For specific types and functions, the appropriate ADC can be selected according to different application requirements.

Review Editor: Huang Fei


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