Alternative: thin-film-on-steel technology combined with ASIC
With respect to drifting, thin-film-on-steel technology is without a doubt the best, allowing high frequencies but having a very small signal-to-noise ratio in comparison to the other two. Particularly when it comes to the evaluation of highly dynamic signals, this places such high demands on the evaluation electronics in the transmitter that most manufacturers of high-speed pressure transmitters fall back to one of the other sensor technologies. Trafag, one of the pioneers, with nearly 35 years of experience, has a different approach: by using the self-developed ASIC (application-specific integrated circuit), tailored precisely to the requirements of the Trafag sensor technology with specific amplifier and filter functions, the disadvantages of the low signal-to-noise ratio could be eliminated and the sensor technology, superior with respect to robustness and long-term stability, can be used even in situations where other manufacturers reach their limits. Because of the coordinated development of the two core technologies - the thin-film-to-steel sensor element and the ASIC- Trafag can combine the responsiveness of a high-speed pressure transmitter with the robustness of a pressure transmitter built for the harshest environments.
During production each pressure transmitter is individually adjusted by calibrating against high-precision pressure standards. During this process, correction parameters for the linearization, zero point and span correction are saved on a chip in the transmitter, in this case directly in the Trafag ASIC. The sensor element consists of sputtered thin-film resistors in a Wheatstone bridge arrangement which are compressed or expanded depending on the pressure induced membrane deformation. Every input signal of the sensor element resulting from the deformation induced change of resistance, is corrected accordingly to the parameter saved in the ASIC, particularly with regard to linearity, zero point and span as well as temperature compensation above or below 25°C.