Precision Circuit Techniques with Low Susceptibility to EMI

Electromagnetic compatibility (EMC) is an increasingly important design aspect of integrated circuits (IC) due to the rapid spread of wireless communication devices and electromagnetic interference (EMI) produced by high current switching in power amplifiers. This electromagnetic emission can couple on cables or wires and be conducted to the IC via package pins. The resulting interference can deteriorate the desired circuit performance and raise severe security concerns.Consequently, stringent standards have been established by industry to enhance EMC of electronic devices. Typical automotive standards for IC level characterization define test conditions where up to 30 dBm (40Vpp) EMI is capacitively injected into the chip in the frequency range from 150 kHz to 1GHz.Hence, in this research several design techniques are proposed that significantly lower EMI susceptibility on the IC level. Firstly, high and low impedance differential input stages are investigated in terms of EMC robustness. Whereas high impedance pairs can only cope with moderate EMI levels, in a low input impedance topology EMI levels can be linearly scaled down, thus allowing operation even under 30 dBm disturbances.Based on the low impedance input architecture an EMI resisting instrumentation amplifier is designed in a direct current feedback topology guaranteeing less than 3 uV offset shift at 30 dBm.As the supply chain typically constitutes a very sensitive entry point for EMI in automotive sensor systems, EMI resistance of voltage regulators is also addressed in this work. A topology with auxiliary supply system is proposed that achieves tolerance of up to 25 dBm disturbance on the supply pin.status: publishe