Thermal conductivity detector compact Spice model based on experimental measurements and 3D simulations

In this paper a novel compact Spice model of a thermal conductivity detector (TCD) is presented and validated against an extensive experimental characterization and 3D simulations. The TCD used is based on the ultra low power (ULP) technology and it has been electrically characterized with different helium and nitrogen gas flow rates, via a microfluidic experimental setup. Extraction of global electro-thermal parameters, exploited for the development of the Spice model, has been performed by using both 3D electro-thermal FEM simulations made with COMSOL Multyphisics® and experimental measurements. The first result we discuss is the good agreement between 3D FEM simulations of the device, made with COMSOL Multiphysics®, and the experiments, with a maximum error of 2.9% for He flow rate of 9 sccm and around 1.8% for the N2 carrier gas at each considered flow rate. We have demonstrated that the Spice model can reproduce very well the FEM simulations for all the gas flow rates and the operating power values taken into consideration, using simulation parameters extracted from FEM data itself. Results of the Spice model compare well also with the real behavior of a TCD device for both the used gases, using parameters either extracted from FEM simulations or calibrated with experimental measurements, with a maximum error of 0.9% for the He flow rate of 0.29 sccm and a maximum error of 0.8% for the N2 flow rate of 10.3 sccm. The novelty of the proposed approach is to provide a useful instrument for the electronic designer who wants to incorporate a Spice electro-thermal model in a simulation environment. The TCD can initially be simulated with an electro-thermal FEM model for a reduced number of operating conditions, then the Spice model can be calibrated and exploited for the electronic design. After device production, the Spice model can eventually be optimized using the experimental results, thus improving the accuracy of the whole electronic circuit simulation.