Simple comparison of ADCs with the same bits is difficult… Solution presented in online seminar

As the importance of data increases, engineers are also increasingly concerned about choosing an ADC (analog-to-digital converter). This is because ADCs, which are essential for electronic devices in various industries and fields, have a significant impact on speed and precision.

Engineers must carefully consider the resolution, accuracy, speed, and response to environmental changes of different types of ADCs and of specific companies.

The ADCs that are currently widely used include the sequential analog-to-digital (SAR) ADC and the delta-sigma ADC. The SAR ADC is fast, but has a resolution of about 10 to 12 bits, while the delta-sigma ADC reduces errors through oversampling and provides an average resolution of 24 bits, but the sampling speed is slow.

For example, as the importance of more precise digital multimeters (DMMs) increases in factory automation and robot development, the role of ADCs is also becoming more important. In such cases, it is appropriate to use a delta-sigma ADC with high precision and signal-to-noise ratio (SNR) performance.

SAR ADCs support fast speeds but have poor resolutions, so they have been used by adding comparators as needed. TI Korea’s Moon Soon-ja said, “As the comparator is installed, the speed becomes slower and the price increases, which is a concern for the research designer.” This is because if the resolution is high, the continuity or SNR may decrease.

Regarding this, Mr. Moon listed 'high resolution, speed, and low price' as the ideal ADC conditions. From a designer's perspective, performance is important, but price is something that cannot be left out. TI's SAR ADC, ADS8900B, integrated the operational amplifier buffer internally because it paid attention to this part. ADS8900B has the characteristics of an ADC, such as a fast speed of 1msps, 20bit resolution, 100db SNR, and noise of plus or minus 1ppm or less. Although the buffer that was external was integrated, it can be manufactured in a smaller size than the external one due to the miniaturization of the manufacturing process.

“Because we go through the internal process of trimming the process, we can reduce errors and distortions and provide accurate reference values,” he said.

Among the related references, he mentioned the ultrasound system circuit design. Mr. Moon said, “In the circuit design design, real-time frequency change is important in the CW Doppler Path, and it is transmitted digitally.” He emphasized the high resolution and fast speed of sending the signal without distortion. Even for ADCs with the same bit, the speed and performance are all different, making a simple comparison difficult.

An online seminar (eeWebinar) explaining the operating principles and related applications of SAR ADC and Delta-Sigma ADC, which are difficult to simply compare because of their operating principles, will be held on Tuesday, the 30th of this month. In addition, time will be spent designing an ADC to see what kind of architecture ADC can be designed for the CW Doppler path of an ultrasound system.