This paper presents methods allowing to provide
galvanically isolated DC voltage measurement with nearly
infinite input impedance. Measurement is based on a
ferroelectric effect, creating hysteretic capacitance vs. bias-
voltage (C-V) dependence of the ordinary multilayer ceramic
capacitors. Voltage measurement is based on AC impedance
sensing of a high-density multilayer ceramic capacitor and
comparing with ground-referred matched capacitor with
corresponding DC bias voltage. Corresponding DC bias voltage
is provided by negative impedance converter and a feedback
network. Despite finite accuracy (~1%), voltage sensing
performed by a capacitor can be advantageous as it allows to
implement AC (high-voltage) coupling, and presents nearly
ideal infinite input impedance. This can be beneficial in a variety
of applications e.g. in power management systems, energy
harvesting applications, or scientific instrumentation
