# US 2014/0190237 A1 · Output specification calibrating apparatus for capacitive pressure sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0190237 A1 - Document ID: US20140190237A1 - Status: Published application - Kind: A1 - Application number: 13/737,189 - Filed: 2013-01-09 - Published: 2014-07-10 - Earliest claimed: 2013-01-09 - Assignees: Auto Industrial Co., Ltd. - Inventors: Kyong M. Park; Kang-Yoon LEE - Web page: https://patentgrep.com/patent/US20140190237A1 ## CPC - G01L 27/00: Testing or calibrating of apparatus for measuring fluid pressure - G01L 9/125: {with temperature compensating means (non electric temperature compensating means G01L19/04)} - G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G) ## Abstract An output specification calibrating apparatus for a capacitive pressure sensor. The output specification calibrating apparatus enables adjustment of non-linearity, offset, and gain of the capacitive pressure sensor in a software manner at the time of shipment. Accordingly, it is feasible to easily adjust output specifications of the capacitive pressure sensor and to thereby meet various needs of customers. ## Claims ### Claim 1 An output specification calibrating apparatus for a capacitive pressure sensor, comprising: an output control circuit configured to convert capacitance changes of a capacitance Cp formed by a primary electrode of the capacitive pressure sensor and a capacitance Cr formed by a reference electrode of the capacitive pressure sensor into an output voltage and output the output voltage; an output specification calibration element configured to comprise at least one output specification offset calibration element, an output specification non-linearity adjustment element, an output specification gain adjustment element, and an output specification temperature compensation element, each element configured to adjust a specification of an output of the output control circuit; a setting unit configured to set electrical property values of the output specification offset calibration element, the output specification non-linearity adjustment element and the output specification gain adjustment element; an external input interface configured to be connected to an external terminal for setting the electrical property values of the output specification offset calibration element, the output specification non-linearity adjustment element and the output specification gain adjustment element; and a temperature compensation circuit configured to set electrical property values of the output specification temperature compensation element. ### Claim 2 (depends on 1) The output specification calibrating apparatus of claim 1, wherein the output control circuit is configured to comprise a switch unit configured to control charge and discharge operations of the capacitance Cp formed by the primary electrode and the capacitance Cr formed by the reference electrode, an integrator configured to receive currents discharged from the capacitance Cp and the capacitance Cr, output the received currents as an output voltage and continue to integrate an error correction signal until an error reaches zero, a power input unit configured to supply a constant power to the capacitance Cp and the capacitance Cr, and a feedback unit configured to amplify an output voltage from the integrator and feed the amplified output voltage back to the capacitance Cp, the capacitance Cr and the power input unit. ### Claim 3 (depends on 2) The output specification calibrating apparatus of claim 2, wherein the output specification offset calibration element is configured to comprise two variable resistors RLin1 and RLin2 being connected in series between a power input V+ and ground, branching off from a series connection contact point, and being connected to an input terminal of the power input unit to calibrate an input voltage offset. ### Claim 4 (depends on 3) The output specification calibrating apparatus of claim 3, wherein the setting unit is configured to set resistances of the two variable resistors RLin1 and RLin2 as electrical property values. ### Claim 5 (depends on 2) The output specification calibrating apparatus of claim 2, wherein the output specification gain adjustment element is configured to comprise a variable resistor ROF being connected to both an inversion input terminal of an amplifier and an output terminal of the amplifier, which amplifies the output voltage from the integrator, to adjust a gain of the amplifier. ### Claim 6 (depends on 5) The output specification calibrating apparatus of claim 5, wherein the setting unit is configured to set a resistance of the variable resistor ROF as an electrical property value. ### Claim 7 (depends on 2) The output specification calibrating apparatus of claim 2, wherein the output specification temperature compensation element is configured to comprise a variable resistor ROI being connected to an inversion input terminal of an amplifier and an output terminal of the integrator, to compensate for changes in an output voltage of the amplifier due to temperature change. ### Claim 8 (depends on 7) The output specification calibrating apparatus of claim 7, wherein the temperature compensation circuit is configured to set a resistance of the variable resistor ROI as an electrical property value. ### Claim 9 (depends on 2) The output specification calibrating apparatus of claim 2, wherein the output specification non-linearity adjustment element is configured to comprise a variable resistor RLinF being connected to both an output terminal of the feedback unit and an input terminal of the power input unit, and connecting a pair of the capacitance Cp formed by the primary electrode of the capacitive pressure sensor and the capacitance Cr formed by the reference electrode between the output terminal of the feedback unit and the variable resistor RLinF to improve non-linearity of the capacitive pressure sensor. ### Claim 10 (depends on 9) The output specification calibrating apparatus of claim 9, wherein the setting unit is configured to set a resistance of the variable resistor RLinf as an electrical property value.