Evaluation unit for determining the resistance of a semiconducting metal oxide sensor and use thereof

摘要

By applying a carrier signal with frequency fr to the metal oxide sensor, after which a switched-capacitor band-pass filter is connected, and by applying a signal, the frequency of which is rigidly coupled to the frequency fr, to the clock input of the switched-capacitor band-pass filter, the filter delivers a drift-free and largely interference-independent measurement signal. <IMAGE>