Low Voltage Floating Supply in Monolithic High Voltage Technology for High dV/dt Applications

This paper presents two alternative evolutions of the previous presented floating power supply in monolithic high voltage technology. These circuits are used for feeding front-end circuitry realized inside the floating pocket of a current sensor chip which transduces the phase current of a triphase AC servodrive motor. The main feature of this supply is that the floating n-epi pocket it is realized in, is biased with a voltage lower than the maximum voltage value present in the pocket itself. The presented schemes are not affected by the charge injection problem caused by high dV/dt typical of this applications. Results of the most relevant simulations are reported. The circuits have been included in two test chip whose microphotograph is shown.