Quartz Planar Multijunction Thermal Converter as a New AC-DC Current Transfer Standard up to 1 MHz

The new generation of PMJTCs on quartz membranes and on quartz crystal chips developed at the PTB results in new ac-dc current transfer standards for the current of 10 mA and the frequency range from 10 kHz to 1 MHz, accompanied with small uncertainties. For a PMJTC with a heater resistance of 240 Omega the uncertainties for frequencies up to 100 kHz are smaller than 1 muA/A and up to 1 MHz they increase to 5 muA/A (k=1). A model for the PMJTC has been developed which allows calculating the ac-dc current transfer difference as well as the attributed uncertainties. The agreement of the simulation and the measurement were tested for high heater resistances of 700 Omega and 240 Omega, for which quite large ac-dc differences are calculated. The good agreement validates the model