Data Converter Testing
Data converters fall into several categories. Here we will discuss two popular types, analog to digital (ADC) and digital to analog (DAC). ADCs and DACs can be found embedded in larger system-on-a-chip (SOC) and system-in-package (SIP) devices or stand-alone. The information on this page is focused on stand-alone data converters.
ADCs and DACs are further segmented by whether they are high speed or high precision solutions. High precision converters are now exceeding 24 bits of resolution. The majority of devices with this level of precision usually operate at a relatively low frequency, less than 2Ms/s. High speed converters, on the other hand, go as high as 16 bits of resolution and in some cases operate at greater than 500MS/s. The highest volume converters are 16 bits and below with the sweet spot at 12 bits.
The numbers of bits of resolution, and the sampling speed of the device, have a significant influence on the test solution required.
For high resolution, precision data converters these tests can be extremely difficult to make, especially in a high volume production solution. You need to start with a tester designed for mixed signal testing because the noise floor and signal fidelity of the tester has a significant impact on the ability to make an accurate, repeatable and reproducible measurement. For ADC testing you need to have an extremely accurate DC source that can change levels in very small increments. For DAC testing you need an instrument capable of measuring extremely small changes in the output of the device. Of course cost of test is also a major consideration so you need to do the critical testing of converters in as fast a time as possible and preferably testing multiple devices at a time.