Characterizations of FPGA chip electromagnetic emissions based on GTEM cell measurements

Miniaturized, dense integration and high operating frequencies of FPGAs are factors contributing to electromagnetic emissions. Consequently the radiation issue that used to be discussed at PCB level has shifted to component level. Thus it is of interest and challenging to investigate chip electromagnetic performance. GTEM cell is widely accepted to characterize chip emission and the common measurement practice is mounting the device under test at the GTEM cell body. This paper presents an alternative approach to measure electromagnetic emissions by locating the entire FPGA test board inside the GTEM cell instead of mounting it at the wall of the cell. Before measurements, the FPGA board is properly shielded with metallic enclosure to avoid unintentional contribution from supporting components on the board. During measurements, the shielded FPGA board is arranged in horizontal or vertical positions and for each position the FPGA chip is configured with two different logic circuits. The results have shown a significant impact of FPGA chip positions and IO pins on the electromagnetic emissions.