A Research On Stability Of Wireless Sensor Network Node PCB Based On Electromagnetic Field FEM

In this paper, in order to improve the working stability of wireless sensor network nodes, a research has been made on the signal integrity, electromagnetic compatibility and power integrity of its PCB.Taking online monitoring of the transmission line as application background, technical solutions of gateway node and monitoring node are designed, and the chip of each module is selected. Electromagnetic radiation and crosstalk model is built, besides, design method of PDN, finite element method and rated implement software Ansoft Siwave/Designer is introduced.After completion of node hardware circuit design, automatic routing PCB and adjusted PCB is simulated using Ansoft Siwave/Designer, and PCB routing is completed. Details are as follows:1. Simulation results of monitoring node PCB show that voltage of chip’s5V power supply pins increases from4.771V to4.997V and power supply voltage is controlled in5%of rated voltage by widening, shortening power supply lines in terms of power integrity; overshoot amplitude of data lines decreases from298.4mV to186.1mV and signal line noise is controlled in the15%of signal swing by using135-degree corner and expanding line spacing in terms of signal integrity; the maximum of electric field at3m decreases from68dBμV/m to32dBμV/m and radiated electric field reached limit requirements of CISPR22by reducing oscillator’s circle area in terms of electromagnetic compatibility.2. Simulation results of gateway node kernel board show that the maximum of3.3V PDN input impedance decreases from2.48Ω to1.09Ω and power supply voltage is controlled in5%of rated voltage by adding decoupling capacitor at the place where resonant amplitude is biggest in terms of power integrity; overshoot amplitude of data lines decreases from897mV to90mV and signal line noise is controlled in the15%of signal swing by signal lines having common reference plane and termination in terms of signal integrity; the maximum of near megnetic field decreases from57.27mA/m to52.46mA/m and electromagnetic disturbance on adjacent transmission lines is weakened by eliminating continuous apertures in terms of electromagnetic compatibility.3. Simulation results of gateway node bottom board show that voltage of chip’s4V power supply pins increases from3.873V to3.941V and power supply voltage is controlled in5%of rated voltage by widening, shortening power supply lines in terms of power integrity; overshoot amplitude of signal lines decreases from2.3479V to634mV and signal line noise is controlled in the15%of signal swing by reducing the length of transmission lines and termination in terms of signal integrity; the maximum of electric field at3m decreases from91dBμV/m to52dBμV/m and radiated electric field reached limit requirements of CISPR22by using a large mental plane close to lines in terms of electromagnetic compatibility.In summary, after the adjustment of nodes’ automatic routing PCB, the signal integrity, electromagnetic compatibility and power integrity is improved and the working stability of nodes is enhanced.