APEMC 2021: Influence of Layout Parasitics on EMI Improved Folded Cascode Amplifier Input Stages

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Nowadays, there are hardly any technical applications that do not rely on the advantages of microelectronics. It is therefore not surprising that well over a hundred control units with countless integrated circuits are installed in modern motor vehicles. Due to the increasing integration density of current semiconductor manufacturing technologies, it is now possible to combine millions of digital logic gates together with mixed-signal devices, as well as power electronics components into a single integrated circuit (IC). If such ICs are to be used for safety features in automotive applications such as in airbags or anti-lock braking systems, they usually have to ensure a high level of electromagnetic compatibility (EMC) to work properly within their electromagnetic environment. For reliable and safe operation, it is very important that the used ICs are capable of recording sensor signals reliably and accurately even in the presence of EMI. Operational amplifiers are very often used as sensor interfaces as part of electronic sensor systems. Often the power supply and the inputs of such operational amplifiers are directly connected to the cable harness and therefore especially exposed to very harsh electromagnetic environments. As a result, operational amplifiers can be severely disturbed and often a so-called EMI induced offset occurs at their outputs.

In this work we compared three EMI improved differential input pair structures, using concepts of filtering and linearisation in terms of their EMI susceptibility. We paid special attention to the differences in the behaviour of the structures at the design stage and the layout stage, where we also considered layout-specific parasitics that can affect circuit performance. We compared the investigated structures in terms of EMI induced offset voltage, electromagnetic interference rejection ratio (EMIRR), layout considerations, differential and common mode gain, gain-bandwidth product (GBWP), stability, power consumption, area requirement (estimation vs. implementation) etc.
Period1 Oct 2021
Event titleAsia Pacific International Symposium on Electromagnetic Compatibilty 2021
Event typeConference
LocationBali, IndonesiaShow on map
Degree of RecognitionInternational