MULTISTEP FEEDBACK CAPACITOR SWITCHING SCHEME

• Main Authors: LI ZHE-MING, CHUNG TAE-SONG, RAFAEL BETANCOURT, SAIKRISHNA GANTA, JOHN MICHAEL WEINERTH, FARZANEH SHAHROKHI
• Format: Patent
• Language: English; Japanese
• Published: 25.04.2019
• Subjects: MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PHYSICS; TESTING

To provide a method for measuring capacitance.SOLUTION: A method for measuring capacitance comprises the steps of: resetting 502 a feedback capacitor of a capacitance measurement circuit to a first voltage level; coupling 506 a sensor electrode to a first input part of a differential amplifier for starting a measurement phase; and closing 508 a first switch of a plurality of switches between the feedback capacitor and an output part of the differential amplifier. When the first switch is closed, a first resistance value is applied to the first switch coupled to the feedback capacitor in series. The method further comprises the steps of: turning a second switch of the plurality of switches on after a certain time delay; generating a second resistance value in the second switch coupled to the first switch in parallel; closing 510 remainder of the plurality of switches after the certain delay after closing the first switch; and operating 512 the differential amplifier for integrating electric charges of the sensor electrode for absolute capacitance corresponding to coupling between the sensor electrode and an input object to be measured.SELECTED DRAWING: Figure 5 【課題】静電容量測定の方法を提供する。【解決手段】静電容量測定回路のフィードバックコンデンサを第１の電圧レベルにリセット５０２し、測定フェーズを開始するためにセンサ電極と差動増幅器の第１の入力部とを結合５０６し、フィードバックコンデンサと差動増幅器の出力部との間の複数のスイッチの第１のスイッチを閉じる５０８ことを含む。第１のスイッチを閉じるときフィードバックコンデンサと直列に結合される第１のスイッチに第１の抵抗値を適用する。さらに、ある時間遅延の後に、複数のスイッチの第２のスイッチをオンし、第１のスイッチと並列に結合される第２のスイッチにおいて第２の抵抗値を生じさせ、第１のスイッチを閉じてからある遅延の後に複数のスイッチの残りを閉じ５１０、センサ電極と入力物体との間の結合に相当する絶対静電容量が測定されるようにセンサ電極の電荷を積分するために差動増幅器を動作させる５１２ことを含む。【選択図】図５