A photomultiplier high voltage power supply incorporating a ceramic transformer

The article describes the circuit and operation of a photomultiplier high voltage power supply incorporating a ceramic transformer, where a ceramic transformer takes the place of the conventional magnetic transformer. The ceramic transformer utilizes piezoelectric effect to generate high voltage. The ceramic transformer is constructed from a ceramic bar and does not include any magnetic material. So the transformer is free of leakage of magnetic flux and can be operated under a strong magnetic field. The ceramic transformer shows sharp resonance, and then voltage amplification of the transformer depends on frequency. The output high voltage is stabilized by feedback, where the frequency dependence is utilized. Output of the transformer is rectified to produce the output high voltage, which is fed back to a voltage-controlled oscillator. The oscillator adjusts the frequency of oscillation according to the output voltage of an error amplifier, where the error amplifier compares the output high voltage with a reference voltage. The photomultiplier high voltage supply is capable of supplying a high voltage ranging from 1500 volts to 2500 volts against the load of 20 megohm with magnitude of ripples being at a prescribed level on the high voltage, where the load is a breeder of the photomultiplier. Magnitude of the ripples is proportional to the amount of the load current. The ripples limit the load current to the photomultiplier