Impedance measurement with high voltage DC bias

Discussion in 'The Projects Forum' started by PePu, Feb 9, 2009.

  1. PePu

    Thread Starter New Member

    Feb 8, 2009
    I would like to measure impedance vs. frequency characteristics of ferroelectric samples under high voltage DC bias (frequency range 40 Hz -10 MHz). The samples have static capacitance usually between 100 and 300 pF (about 4 x 1.5 x 0.4 mm3). I intend to use a silicone oil bath to avoid arcing.


    First, a simple circuit with blocking capacitors (C = 0.1-2 μF - see attached file) and resistors (R = 0.2-1 MΩ) has crossed my mind. However, I worry about the analyzer in case the sample gets broken (i.e. a conductive path creates through the sample). The energy stored in blocking capacitors might and probably will destroy the analyzer's input.

    Do you think there is a simple workaround or more complex circuit is necessary (e.g.

    Many thanks for any suggestions.