Designing and understanding a PCB trace used to deliver EMI to a CMOS microchip using a GTEM

The overarching purpose of this research is to enable the testing and characterisation of the effects that electromagnetic interference (EMI) has on complimentary metal-oxide-semiconductor (CMOS) devices. In particular we are investigating how radiated high-powered microwaves (HPM) can alter the behaviour of a CMOS inverter by inducing upset conditions such as logic error (bit flip) and latch-up. This type of testing typically requires an anechoic chamber, however, these chambers are cost prohibitive in many cases. Instead, this paper begins the development of an economically viable alternative to the anechoic chamber for HPM experiments on microelectronics. To achieve this we intend to utilize a gigahertz transverse electromagnetic (GTEM) cell where a custom printed circuit board (PCB), suitable for mounting within the upper hatch aperture, will host a CMOS microchip in addition to a PCB trace positioned for electromagnetic field exposure within the chamber. Our simulations reveal that the end-fire behaviour of this PCB trace, which is acting as the wire in a field-to-wire experiment, is a simple mechanism which can capture and deliver incident plane waves generated by the septum to the microchip. We also find that there is a direct relationship between substrate height (PCB thickness), and the peak effective antenna length of the trace, where the physical length of the trace determines the frequency at which these peaks occur. Then, by applying appropriate modelling fundamentals, we are able to predict this behaviour. Finally we establish that to reach a voltage range considered HPM by the input of the microchip, we comparatively need 3 orders of magnitude less power than equivalent far-field experiments in an anechoic chamber.