New Thin-Film Multijunction Thermal Converter Design for Improved High-Frequency Performance

New thin-film planar multifunction thermal converters (PMJTC) were developed to improve the high-frequency ac-dc transfer differences. The heater resistor and thermocouples of these PMJTCs were produced on different substrates: an AIN chip for the heaters and polyimide film for the thermocouples, using simple fabrication processes. The thermocouples were moved from the conventional high-potential heater position, and placed close to the ground electrode of the input circuit. This new configuration upgrades the performance of ac-dc transfer differences above 10 kHz by improving both the electromagnetic coupling between the heater and thermocouples and the output resistance of thermocouples. Using a high thermal conductivity AIN substrate, through which heat is conducted from the heater to the hot junctions of the thermocouples, almost the same sensitivity as that of PMJTCs on silicon is obtained.