DA converter is a circuit that converts digital quantity to analog quantity. It is mainly used in data transmission system, automatic test equipment, medical information processing, TV signal digital processing, image signal processing and recognition, digital communication and voice information processing etc.
DA converter classification
By digital input mode: parallel input and serial input DA converters.
By analog output mode: current output and voltage output DA converters.
By DA conversion resolution: low resolution, medium resolution, and high-resolution DA converters.
DA converter performance indicators
1. Resolution ratio
It shows resolving power of DA converter to the analog. It is defined as the ratio of the reference voltage to 2n, where n is the digit number of DA converter.
It is the equivalent output analog voltage with the input binary number lowest effective bit LSB (Least Significant Bit). The abbreviation is 1LSB. In actual use, the digit number of input digital is generally used to represent the resolution size, and the resolution depends on the digit number of DA converter.
2. Stable time (also called conversion time)
When the input binary number change is full range, the required time while DA converter output gets to end value ±1/2LSB. For DA converter of which output is current type, the stable time is very short (just about a few μs). For DA converter of which output is voltage, its stable time mainly depends on the response time of the operational amplifier.
3. Absolute precision
It refers to the deviation between the actual output value and the theoretical value of the DA converter when a digital full scale is entered. This deviation is represented by the lowest effective LSB fraction, such as ±1/2LSB or ±1LSB.