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A capacitance detection circuit and a capacitance sensing circuit

A capacitance detection and detection circuit technology, which is applied in the field of microelectronics, can solve problems such as limiting the application of Boxcar capacitance detection circuits

Active Publication Date: 2019-03-01
QST CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the application of the Boxcar capacitance detection circuit in the sensor is limited

Method used

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  • A capacitance detection circuit and a capacitance sensing circuit
  • A capacitance detection circuit and a capacitance sensing circuit
  • A capacitance detection circuit and a capacitance sensing circuit

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Experimental program
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Effect test

Embodiment 1

[0062] see Figure 3 to Figure 6 , The invention discloses a capacitance detection circuit, the capacitance detection circuit includes a low-noise analog capacitance detection circuit, a common-mode signal compensation capacitor, and a self-calibration circuit, and the capacitance detection circuit is connected with a sigma delta modulator.

[0063] The low-noise analog capacitance detection circuit is used to detect the capacitance of the MEMS structure (of course, it can also be other capacitive sensors, and the low-noise analog capacitance detection circuit can be used to detect other capacitive sensors).

[0064] The low-noise analog capacitance-sensing circuit consists of a common-mode compensation capacitor C m , sensor capacitance C s0 and ΔC and switch SW 0 ~SW 5 A switched capacitor circuit consisting of a first amplifier, a second amplifier, and an amplifying capacitor C L and switch SW 0 A transconductance capacitor amplifier composed of; finally forming an amp...

Embodiment 2

[0076] A capacitance detection circuit includes a low-noise analog capacitance detection circuit, a common-mode signal compensation capacitance, and a self-calibration circuit.

[0077] The low-noise analog capacitance detection circuit is used to detect capacitance (such as the capacitance of MEMS structure), such as Figure 4 shown.

[0078] The self-calibration circuit is connected with the common-mode signal compensation capacitor to compensate the change of the common-mode voltage of the low-noise analog capacitance detection circuit itself; the common-mode signal compensation capacitor is automatically found by the self-calibration circuit when the MEMS inspection circuit is started. capacitive balance point to compensate for changes in common-mode voltage, such as Figure 5 shown.

[0079] By adding a common-mode compensation capacitor, the common-mode variation at the input of the first amplifier is reduced to: The low-frequency gain is increased to: The equivalent...

Embodiment 3

[0091] A capacitance sensing circuit includes a low-noise analog capacitance detection circuit, a common-mode signal compensation capacitance, a self-calibration circuit and a sigma delta modulator.

[0092] The low-noise analog capacitance detection circuit is used to detect the capacitance of the MEMS structure (also can be used to detect other capacitance sensors), such as Figure 4 shown.

[0093] The self-calibration circuit is connected with a common-mode signal compensation capacitor to compensate for the variation of the common-mode voltage of the low-noise analog capacitance detection circuit itself; when the MEMS inspection circuit is started, the self-calibration circuit automatically finds a capacitance balance point to compensate The change in common-mode voltage; the common-mode change at the input of the first amplifier will be reduced to: The low frequency gain will be increased to: The signal-to-noise ratio will increase to: The equivalent input offset cap...

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Abstract

The present invention discloses a capacitance detection circuit and a capacitance sensing circuit. The capacitance detection circuit comprises a low-noise analog capacitance detection circuit, a common-mode signal compensation capacitor and a self-calibration circuit. The low-noise analog capacitance detection circuit is used for detecting the capacitance of an MEMS structure. The self-calibration circuit is connected to the common-mode signal compensation capacitor and is used for compensating the change of the common-mode voltage of the low-noise analog capacitance detection circuit. The common-mode signal compensation capacitor automatically searches a capacitance balance point through the self-calibration circuit when an MEMS inspection circuit starts and compensates the change of the common-mode voltage. The capacitance detection circuit provided by the invention has the advantages of a high signal gain and a high signal to noise ratio.

Description

technical field [0001] The invention belongs to the technical field of microelectronics and relates to a detection circuit, in particular to a capacitance detection circuit; at the same time, the invention also relates to a capacitance sensing circuit. Background technique [0002] In the traditional capacitance detection front-end circuit, generally such as figure 1 shown, using a broadband amplifier and capacitor C L A feedback amplification loop is formed to obtain a very short response time and high gain to ensure that the entire detection circuit is not sensitive to environmental changes. In this detection circuit, by separately controlling the switch SW 1 and SW 2 , convert the charge transferred from the MEMS capacitor into a voltage signal, and make the amplitude of the output signal V 0 Proportional to the displacement detected from the MEMS. However, due to the existence of the sampling operation, the high-frequency components of the broadband will be folded t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R27/26
Inventor 郭鹏陈清平褚洪涛姜杰
Owner QST CORP