D/A and A/D conversion
模拟Signal: Both in time and value 连续
数字Signal: Both in time and value离散
Overview
- D/A conversion: digital signal - analog signal
(D/A converter is referred to as DAC) - A/D conversion: analog signal - digital signal
(A/D converter is referred to as ADC) - Reason for conversion:
D/A conversion
- Classify according to the differences in the internal position weight network (only summarize the case of unipolar output)
| DAC type | internal structure | Analytical method | Remark |
|---|---|---|---|
| Weight Resistor Network DAC |  |
 |
The branch current changes as the input changes |
| Inverted T-shaped electrical network DAC formula must be memorized |
 |
 |
Branch current is constant |
| weight current mode DAC | – | – | Does not require mastery |
| Power capacitor network DAC | – | – | Does not require mastery |
| Switch tree DAC | – | – | Does not require mastery |
A/D conversion
- Fundamental
| step | describe | Remark |
|---|---|---|
| sampling | Convert analog signals that are continuous in events into discrete signals in time | |
| Keep | Ability to maintain the sampled value stably for a period of time until the end of the conversion process | |
| Quantify | Rounding to zero (a signal that is discrete in time is converted into a signal that is also discrete in value, and its numerical value can only be an integer multiple of a specified minimum quantity unit Δ) | There are theoretical errors in quantization that cannot be eliminated; the more bits the ADC has, the smaller the difference between each discrete level, and the smaller the quantization error. |
| coding | The quantized numerical size is converted into the corresponding digital code |
- Quantification method ( must memorize formula )
| type | analyze | in conclusion | Remark |
|---|---|---|---|
| Just reluctant to give up |  |
 |
Quantization error = minimum quantization unit |
| rounding |  |
 |
Quantization error = (1/2) minimum quantization unit |
Example exercises
