A package-board co-design method was applied for a Narrowband Internet of Things (NB-IoT) SiP module. The electromagnetic interference (EMI) generated by the module was studied by improving the transmission quality of radio frequency (RF) signal. The SiP models of the initial design and the optimized design were simulated separately to show that the optimized design significantly increased effective transmission power of the RF signal and suppressed near-field electromagnetic radiation intensity to a certain extent. In addition, the optimized design model was verified by measurement. The measured results show good agreement with the simulated ones and demonstrate that the package-board co-design method can improve the electromagnetic compatibility (EMC) of NB-IoT applications.

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Transverse electromagnetic (TEM) cell is usually used to evaluate the electromagnetic immunity and electromagnetic radiation disturbance of the equipment under test (EUT) and integrated circuit (IC). Affected by the structure of the TEM cell, high-order modes and reflection will be generated in the high frequency range, which will limit the higher frequency applications of the TEM cell. In this paper, the TEM cell specified in IEC61967-2 standard is improved by adopting several methods, including segmented impedance matching, slitting outer conductor, slotting inner conductor, adding absorbing materials, and adding an external shielding box. The results show that the improved TEM cell voltage standing wave ratio (VSWR) is less than 1.2 in 0-3.4 GHz, less than 1.3 in 0-3.75 GHz, and less than 1.5 in 0-4.06 GHz; at the same time, the S-parameter characteristics are better.