Bipolar electrostatic driving for high-resolution isolated battery voltage sensor

Si resonator is applied for measuring the voltage in a highly isolated manner. The resonant frequency shift being affected by the electrical field from the high voltage (supposing the battery) is the working principle. Here, the resonator is electrically floated for the isolation and the outside driving voltage is set to be bipolar for avoiding the fluctuation which will be caused by charging of the resonator. This new method stabilizes the resonant frequency realizing 0.25V accuracy at 80V. Feasibility for measuring the high voltage up to 420V is demonstrated.