Measurement Technique Research And Realization Of High Speed ADC

As the interface between analog circuits and digital circuits, ADC is one of the key modules of the transceiver. With the development of high-speed and high-precision ADC, the analog input is extremely sensitive to noise, so the performance of high-speed ADC is largely influenced by design of the periphery circuit and entire PCB board. Also, there are many factors can affect the dynamic performances of high-speed ADC, such as the amplitude of input signal, clock jitter, coherent sampling, etc. How to effectively evaluate the performance of high-speed ADC has become a hot topic both in domestic and abroad.Combining our research group's needs, illustrated by the example of a 12-bit high-speed ADC: AD9238, this paper conducts the measurement technique research about high-speed ADC and to explore a set of schemes and solutions for high-speed ADC measurement. Specific studies are as follows: firstly, this paper introduces test methods for static characteristics and dynamic characteristics about high-speed ADC, including code density method and digital spectral analysis for dynamic test. Then, design of PCB board for high-speed ADC in test setup is elaborately described. It contains schematic analysis, simulation, PCB layout of high-speed mixed-signal, signal integrity analysis based on IBIS model and power integrity analysis based on PDN network. Then, a test platform with low cost and short development cycle is built with clock source TSW4806 EVM, signal source E4438 C. 1MHz, 10 MHz and 20 MHz analog signal are used to test the characteristics of AD9238 under different input frequencies. Test results show: SFDR is 75 dB,effective number of bits is 10.6 under the sample rate of 60 MHz and 20 MHz analog input. What's more, this paper discusses how dynamic characteristic changes with different input ranges, as well as whether the analog input has a filter or not. Finally, according to the actual result, the factors which lead dissatisfied performance of AD9238 under low frequency is proved and analyzed, which could provide some guidance for testing or engineering application of high-speed ADC.