A wideband monolithic RMS-DC converter using micromachineddiaphragm structures |
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Authors: | Yoon E Wise KD |
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Affiliation: | Silicon Graphics Comput. Syst., Mountain View, CA ; |
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Abstract: | This paper reports a monolithic rms-dc converter for measuring wideband rms signals. Two identical thermoelements for thermal rms-dc conversion are formed using planar diaphragm structures and micromachined dielectric windows. Each thermoelement consists of two polysilicon heaters and a thin-film temperature sensor located on a window and operated at constant temperature using on-chip control feedback circuitry. The thermoelements achieve a thermal efficiency greater than 7°C/mW with a thermal time constant less than 5 ms. The on-chip control circuitry is realized using a standard 3 μm p-well CMOS process with minor modifications for process compatibility with the dielectric window formation. This converter measures rms signals over a full scale range of 1 Vrms, handles crest factors in excess of 5, exhibits a typical nonlinearity of less than 1%, and achieves a 3 dB bandwidth greater than 20 MHz |
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