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Capacitance detection circuit and capacitance sensing circuit

A capacitance detection and detection circuit technology, applied in the field of microelectronics, can solve problems such as limiting the application of Boxcar capacitance detection circuit, and achieve the effects of high signal-to-noise ratio, high signal gain, and small equivalent input offset capacitance

Active Publication Date: 2015-12-02
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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  • Capacitance detection circuit and capacitance sensing circuit
  • Capacitance detection circuit and capacitance sensing circuit
  • Capacitance detection circuit and capacitance sensing circuit

Examples

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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 capacitance, a self-calibration circuit, and the capacitance detection circuit is connected with a sigmadelta 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 amplif...

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 will be increased to: ...

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 sigmadelta 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 is reduced to: The low frequency gain will be increased to: G 0 = G ...

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PUM

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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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IPC IPC(8): G01R27/26
Inventor 郭鹏陈清平褚洪涛姜杰
Owner QST CORP
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