Modulador sigma-delta com sensor termo-resistivo.

Abstract

This work presents a model conception of meter architecture based on null deflection instruments. The model architecture uses a mono bit first order sigma-delta modulator with a thermo-resistive sensor as an integrant part of its loop, substituting the addition and integration operations. The meter architecture presented here is based on electrical equivalence principle in which null deflection operation mode is directly applied with the sensor working at a constant temperature. Sigma-delta modulators with thermo-resistive sensor models were developed for solar radiation and temperature measurements. Simulation results of two models versions, for each application, were shown for an oversampling rate equal to 256. The theoretical model version is fed with continuous current and the other model is fed with pulsed current and can be implemented in a circuit. Architecture models performance analyses were developed based on its transfer functions. From those analyses we obtained the models signal to noise rates and resolutions. The resolutions were compared with oversampled PCM and with typical mono bit first order sigma-delta modulator, with the same oversampling rate. This system gives physics greatness estimation, in digital format, directly from physics greatness and may be integrated with a microsensor.