LOW PASS FILTER SEMICONDUCTOR STRUCTURES FOR USE IN TRANSDUCERS FOR MEASURING LOW DYNAMIC PRESSURES IN THE PRESENCE OF HIGH STATIC PRESSURES
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Abstract
A semiconductor filter is provided to operate in conjunction with a differential pressure transducer. The filter receives a high and very low frequency static pressure attendant with a high frequency low dynamic pressure at one end, the filter operates to filter said high frequency dynamic pressure to provide only the static pressure at the other filter end. A differential transducer receives both dynamic and static pressure at one input port and receives said filtered static pressure at the other port where said transducer provides an output solely indicative of dynamic pressure. The filter in one embodiment has a series of etched channels directed from an input end to an output end. The channels are etched pores of extremely small diameter and operate to attenuate or filter the dynamic pressure. In another embodiment, a spiral tubular groove is found between a silicon wafer and a glass cover wafer, an input port of the groove receives both the static and dynamic pressure with an output port of the groove providing only static pressure. The groove filters attenuate dynamic pressure to enable the differential transducer to provide an output only indicative of dynamic pressure by cancellation of the static pressure.
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Citations
30 Claims
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1-9. -9. (canceled)
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10. A differential pressure transducer, comprising:
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a filter adapted to receive a first pressure comprising a static pressure component and a dynamic pressure component at an input, attenuate at least the dynamic pressure component, and output a filtered second pressure at an output; a diaphragm comprising a first surface and a second surface, wherein the first surface is adapted to receive the first pressure and the second surface is in communication with the output of the filter and adapted to receive the filtered second pressure; and a sensor in communication with the diaphragm and adapted to measure a difference between the first pressure and the filtered second pressure. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A differential pressure transducer, comprising:
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a filter adapted to receive a first pressure comprising a static pressure component and a dynamic pressure component at an input, attenuate at least the dynamic pressure component, and output a filtered second pressure at an output; a first diaphragm comprising a first surface and a second surface, wherein the first surface of the first diaphragm is adapted to receive the first pressure and the second surface of the first diaphragm is in communication with the output of the filter and adapted to receive the filtered second pressure; a second diaphragm comprising a surface, wherein the surface of the second diaphragm is adapted to received the first pressure; a first sensor in communication with the first diaphragm and adapted to measure a difference between the first pressure and the filtered second pressure; and a second sensor in communication with the second diaphragm and adapted to measure the first pressure. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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Specification