40V High Side PSI5 Transceiver with $65\text{dB}\mu \text{V}$ Conducted Emission Level in a BiCMOS Process

Abstract

Controlling ElectroMagnetic Interference (EMI) is critical in analog circuits. Specifically in transceivers high slew rates of voltages and currents can interfere with other nearby electronics. On one such emerging automotive standard viz. the Peripheral Sensor Interface (PSI5), the electromagnetic emission from the SYNC pulse generated by the PSI5 transceiver can interfere during communication with the sensor. Known techniques of adding external filters or using Spread Spectrum methods to reduce EMI are not applicable due to cost over head and strict timing requirements. Hence a digitally assisted pulse shaping technique to generate a SYNC pulse with different slopes along with an induced analog ramp at the start of the SYNC pulse to meet timing requirement is proposed in order to reduce the EMI. BiCMOS process is the best choice for speed, accuracy and protection at 40V. This design is implemented and successfully validated on a 40V BiCMOS process. The conducted emission limit is $65\text{dB}\mu \text{V}$ at 200KHz, fully operational for 6V to 40V battery and 100mA current limitation during short to ground conditions at the output.