MEMS driving circuit and driving method, and integration method

Abstract

The application provides a MEMS driving circuit and driving method, and an integration method.The MEMS driving circuit comprises a DAC module, a multiplexing unit, a sample-and-hold amplifier array, a high-voltage driving amplifier array, a reference voltage source and an SPI module; the DAC module is used for converting a given digital signal into an analog voltage signal; the multiplexing unit is connected with the DAC module; an input end of the sample-and-hold amplifier array is connected with an output end of the DAC module; an input end of the high-voltage driving amplifier array is connected with an output end of the sample-and-hold amplifier array; an output end of the high-voltage driving amplifier array is connected with a MEMS array one by one; the SPI module is connected with the DAC module and is used for transmitting an off-chip control signal to an on-chip voltage value and timing control.The application has the technical effect of greatly reducing the wiring length of the driving circuit and the MEMS array and enabling accurate control of the whole MEMS array.

Description

Technical Field

[0001] This invention belongs to the field of driving circuit technology, specifically relating to a MEMS driving circuit and driving method, and integration method. Background Technology

[0002] Electrostatically actuated MEMS devices have attracted significant attention in the field of microelectromechanical systems (MEMS) due to their ability to achieve high energy density and large driving force. Electrostatic actuation is characterized by low power consumption, fast response speed, and compatibility with CMOS circuits. Micro-devices utilizing electrostatic principles are commonly used in many products in the automotive, aerospace, biomedical, and consumer markets. The working principle of electrostatically actuated MEMS devices is to use electrostatic force to control tiny mechanical structures. Electrostatic MEMS devices typically consist of metal electrodes and insulating layers. By applying a voltage to the electrodes, the electrostatic force between the electrodes changes, thereby controlling the change in the mechanical structure. The applications of electrostatic MEMS are very wide-ranging. They can be used to manufacture biomedical chips to detect the concentration and type of microbial molecules, as miniature photonic devices to adjust the direction and wavelength of light beams, and in the communications field to achieve wireless communication.

[0003] Electrostatic MEMS devices used for optical components typically consist of mirrors with parallel-plate capacitors. For array MEMS, the surface of each cell is supported by a cantilever beam that can respond to a certain range of analog voltages, thereby supporting the movement of the MEMS parallel plates perpendicular to the mirror plane and achieving beam manipulation. For optical field manipulation applications, the displacement of the parallel plates in the array needs to be individually tunable. This can be achieved by applying individual voltages to achieve the desired displacement spacing of the MEMS cells. For driving array-type MEMS devices, although the array can be driven using PCB-level multi-channel DACs, driver amplifier circuits, and other modules, the problem is that if the array is large, the corresponding board-level driver circuit is also large in size and volume, making it unsuitable for small microsystem applications. In addition, the long traces between the board-level driver circuit and the MEMS device can lead to IR drop (voltage drop) caused by the traces, resulting in a mismatch in the actual driving voltage applied to different cells of the array MEMS.

[0004] Existing MEMS array driving circuits are typically implemented using board-level DACs (digital-to-analog converters) and amplifiers. For MEMS devices with large array sizes, a large number of DACs and amplifiers are required, resulting in larger size and longer traces, which can lead to mismatch in MEMS driving voltage. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a new technical solution for MEMS driving circuit and driving method and integration method.

[0006] According to a first aspect of the present invention, a MEMS driving circuit is provided, which uses CMOS technology to integrate the array MEMS driving circuit and the MEMS array at the chip level to form a MEMS-CMOS integrated chip.

[0007] Specifically, the MEMS driving circuit includes:

[0008] A DAC module and a multiplexing unit are provided. The DAC module is used to convert a given digital signal into an analog voltage signal. The multiplexing unit is connected to the DAC module and is used to split the analog voltage signal output by the DAC module into multiple sub-signals.

[0009] A sample-and-hold amplifier array, wherein the input terminal of the sample-and-hold amplifier array is connected to the output terminal of the DAC module, and is used to hold the analog voltage signal output by the DAC module;

[0010] A high-voltage drive amplifier array, the input of which is connected to the output of the sample-and-hold amplifier array, is used to amplify the analog voltage signal output by the DAC module to a preset drive voltage range; the output of the high-voltage drive amplifier array is connected to a MEMS array.

[0011] A reference voltage source, which is connected to the DAC module, is used to provide a reference voltage to the DAC module;

[0012] The SPI module, which is connected to the DAC module, is used to transmit external control signals to the internal chip for voltage and timing control.

[0013] Optionally, the MEMS driving circuit also includes:

[0014] A buffer is provided, through which the input of the sample-and-hold amplifier array is connected to the output of the DAC module.

[0015] Optionally, the MEMS driving circuit also includes:

[0016] The SPI module and the DAC module are connected via registers.

[0017] Optionally, the reference voltage source is a bandgap reference voltage source.

[0018] Optionally, the DAC module adopts an R-2R structure.

[0019] Optionally, the output of the DAC module is connected to the input of the sample-and-hold amplifier array via a unity-gain amplifier.

[0020] Optionally, the sample-and-hold amplifier in the sample-and-hold amplifier array is a capacitor inverting type structure.

[0021] Optionally, the high-voltage drive amplifier in the high-voltage drive amplifier array consists of a low-voltage section and a high-voltage section;

[0022] The low-voltage section is compatible with the output of the sample-and-hold circuit, while the high-voltage section is compatible with the driving voltage required by the MEMS array.

[0023] According to a second aspect of the present invention, a control method for a MEMS driving circuit is provided, applied to the MEMS driving circuit as described in the first aspect, comprising:

[0024] The serial input data DATA_IN is converted into n-bit parallel input digital data by a serial-to-parallel converter under the control of the clock CLK_DAC, where n represents the precision of the DAC circuit. The n-bit parallel input digital data is then converted into an analog output level by the DAC module.

[0025] The analog voltage signal output by the DAC module is sampled sequentially by the sample-and-hold circuits of each output channel under the control of the clock control signal CLK_SH. The sampling results are amplified and output by the amplifier circuit.

[0026] Optionally, the MEMS driving circuit is compatible with the SPI protocol.

[0027] According to a third aspect of the present invention, an integration method is provided for integrating a MEMS driving circuit as described in the first aspect with a MEMS array, comprising:

[0028] First, the driving circuit, MEMS fixed mirror, optical thin film, and MEMS-CMOS metal interconnect are fabricated using CMOS technology.

[0029] Secondly, SOI technology was used to fabricate wafer-level optical thin films for MEMS devices and to prepare movable structures.

[0030] Secondly, the CMOS wafer and the SOI wafer are bonded together;

[0031] Finally, the back silicon is removed to form a CMOS-MEMS integrated chip.

[0032] One technical advantage of this invention is that:

[0033] In this embodiment, CMOS technology is used to integrate the array MEMS driving circuit and the MEMS array at the chip level to form a MEMS-CMOS integrated chip. The MEMS-CMOS integrated chip can greatly reduce the trace length of the driving circuit and the MEMS array. Through the cooperation of DAC module, multiplexing unit, sample and hold amplifier array, and high voltage drive amplifier array, precise control of the entire MEMS array can be achieved, further reducing the power consumption of the entire system. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a MEMS driving circuit according to an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of the bandgap reference voltage source of a MEMS driving circuit according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the structure of a DAC module in a MEMS driving circuit according to an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the sample-and-hold amplifier of a MEMS driving circuit according to an embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram of the structure of a high-voltage drive amplifier in a MEMS drive circuit according to an embodiment of the present invention;

[0039] Figure 6 This is an SPI timing diagram of a MEMS driving circuit according to an embodiment of the present invention;

[0040] Figure 7 This is an output timing diagram of a MEMS driving circuit according to an embodiment of the present invention.

[0041] In the diagram: 1. MEMS driver circuit; 2. Serial-to-parallel converter; 3. Register; 4. DAC module; 5. Buffer; 6. Sample-and-hold amplifier; 7. High-voltage driver amplifier. Detailed Implementation

[0042] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0043] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0044] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0045] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0046] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0047] According to the first aspect of the invention, see Figure 1 This invention provides a MEMS driving circuit that uses CMOS technology to integrate the array MEMS driving circuit and the MEMS array at the chip level to form a MEMS-CMOS integrated chip. The MEMS driving circuit can be applied to products such as spectral analysis, beam shaping, and spectral imaging.

[0048] Specifically, the MEMS driving circuit 1 includes:

[0049] DAC module 4 and multiplexing unit: the DAC module is used to convert a given digital signal into an analog voltage signal; the multiplexing unit is connected to the DAC module and is used to split the analog voltage signal output by the DAC module into multiple sub-signals; for example, the DAC module adopts a current-driven, resistor-string, or other structure.

[0050] A sample-and-hold amplifier array (i.e., a sample-and-hold circuit) is provided, with its input connected to the output of the DAC module. This array holds the analog voltage signal output by the DAC module and samples it via a multiplexer to transmit the signal to a downstream high-voltage drive amplifier array. The sample-and-hold amplifier array includes multiple sample-and-hold amplifiers, and each sub-signal output by the DAC module corresponds to one of the sample-and-hold amplifiers in the array. For example, the sample-and-hold amplifiers can be switched onto the input of a subsequent high-voltage drive amplifier.

[0051] A high-voltage drive amplifier array (i.e., a high-voltage drive circuit) is provided, the input of which is connected to the output of the sample-and-hold amplifier array. This array amplifies the analog voltage signal output by the DAC module to a preset drive voltage range, thus satisfying the drive voltage range required for the electrostatic drive of the MEMS array. The output of the high-voltage drive amplifier array is connected to each MEMS array element. The high-voltage drive amplifier array includes multiple high-voltage drive amplifiers 7, and the sample-and-hold amplifier, high-voltage drive amplifier, and array elements of the MEMS array correspond one-to-one, providing different drive voltages independently to different array elements of the MEMS array.

[0052] A reference voltage source, connected to the DAC module, is used to provide an accurate reference voltage to the DAC module;

[0053] The SPI module, connected to the DAC module, is used to transmit external control signals to the on-chip environment for voltage and timing control. Specifically, the SPI module provides programmable voltage codes to the MEMS driver circuit via external control signals and a clock signal, enabling on-chip conversion between digital and analog voltage signals.

[0054] In this embodiment, CMOS technology is used to integrate the array MEMS driving circuit and the MEMS array at the chip level to form a MEMS-CMOS integrated chip. The MEMS-CMOS integrated chip can greatly reduce the trace length of the driving circuit and the MEMS array. Through the cooperation of DAC module, multiplexing unit, sample and hold amplifier array, and high voltage drive amplifier array, precise control of the entire MEMS array can be achieved, further reducing the power consumption of the entire system.

[0055] Due to the high stability of MEMS technology and the good compatibility between MEMS arrays and CMOS technology, using CMOS technology to fabricate MEMS driving circuits and integrating them with MEMS arrays at the chip level can realize MEMS-CMOS integrated chips that are small in size, highly integrated, and have precise and controllable voltage.

[0056] Furthermore, the MEMS driving circuit in this application embodiment is mainly applied to array MEMS electrostatic driving devices. It is based on CMOS technology and uses a multiplexed DAC module, a sample-and-hold circuit, and a high-voltage driving circuit as core components. Each functional module is used to realize the individual driving of the MEMS array, so as to be suitable for beam shaping applications such as array-type MEMS electrostatic filters.

[0057] Compared to the traditional PCB-level multi-channel DAC solution, the MEMS driving circuit of this application aims to improve the integration of the entire system by monolithically integrating the MEMS-CMOS structure. This circuit can not only be integrated with MEMS devices at the chip level, but also provide a stable and accurate programmable driving voltage, enabling independent tuning of different driving voltages for different array units of the MEMS array. It is small and lightweight, and easy to be mounted on a variety of miniaturized optical devices to achieve low power consumption and low cost applications.

[0058] Optionally, the MEMS driving circuit also includes:

[0059] Buffer 5 is used to connect the input of the sample-and-hold amplifier array to the output of the DAC module.

[0060] In the above embodiment, the buffer is used to improve load driving capability. The buffer connects the input of the sample-and-hold amplifier array to the output of the DAC module, which improves the stability and reliability of the circuit.

[0061] Optionally, the MEMS driving circuit also includes:

[0062] Register 3 is used to connect the SPI module and the DAC module.

[0063] In the above implementation, the register is used to temporarily store external SPI instructions to enable communication with the on-chip digital module. Its capacity is relatively small, but its read / write speed is very fast, meeting the needs of short-term storage. At the same time, the register can significantly improve operational speed and performance.

[0064] Optionally, see Figure 2The reference voltage source is a bandgap reference voltage source. Because the bandgap reference voltage source maintains a very stable output voltage under various environmental conditions, it provides more reliable performance for the DAC module.

[0065] See Figure 3 The reference voltage VREF output of the reference voltage source is connected to the DAC module, which can employ an R-2R structure. For an n-bit precision DAC, n sets of R-2R resistors are used. The output Vo of the DAC module is connected to the input of a subsequent sample-and-hold amplifier through a unity-gain amplifier to improve its driving capability.

[0066] Optionally, see Figure 3 The DAC module employs an R-2R structure. This facilitates improved stable driving force through the interaction between the DAC module and the reference voltage source.

[0067] Optionally, the output of the DAC module is connected to the input of the sample-and-hold amplifier array via a unity-gain amplifier. This helps ensure the accuracy and stability of signal transmission.

[0068] Optionally, see Figure 4 The sample-and-hold amplifiers in the sample-and-hold amplifier array are capacitor inverted type structures.

[0069] In the above embodiment, the sample-and-hold amplifier employs a capacitor flip-around (FA-S / H) structure. This structure utilizes the different connections of capacitor C in sampling and holding modes to transfer the sampled voltage Vin to the output, achieving Vout = Vin. Switches K0, K1, and K2 are time-complementary and overlap, controlling the sampling and holding processes respectively. The input-related charge injection, signal feedthrough, and aperture error introduced by K0 can lead to gain error and nonlinearity. By employing a lower plate sampling technique to disconnect K1 before K0, charge injection and signal feedthrough can be eliminated, and aperture error can be significantly reduced. Multiple sample-and-hold amplifiers are used, the same number as the array cells of the driven MEMS array.

[0070] Optionally, see Figure 5 The high-voltage drive amplifier in the high-voltage drive amplifier array consists of a low-voltage section and a high-voltage section;

[0071] The low-voltage section is compatible with the output of the sample-and-hold circuit, while the high-voltage section is compatible with the driving voltage required by the MEMS array.

[0072] In the above embodiments, the high-voltage drive amplifier can provide amplified voltage drive for the array cells of the MEMS array.

[0073] In one specific implementation, one electrode in the array cell of the array MEMS is grounded with the circuit, and the other electrode is connected to the output terminal of the high-voltage drive circuit.

[0074] In this embodiment, the array MEMS driving circuit can employ a MEMS surface process compatible with CMOS technology to achieve MEMS-CMOS integrated applications. Its advantages include high integration density, low power consumption, and the ability to achieve precise control of MEMS devices, improving their precision control level in optical filtering and optical shaping applications.

[0075] According to a second aspect of the present invention, a control method for a MEMS driving circuit is provided, applied to the MEMS driving circuit as described in the first aspect, comprising:

[0076] The serial input data DATA_IN is converted into n-bit parallel input digital data by a serial-to-parallel converter under the control of the clock CLK_DAC, where n represents the precision of the DAC circuit. The n-bit parallel input digital data is then converted into analog output level by the DAC module.

[0077] The analog voltage signal output by the DAC module is sampled sequentially by the sample-and-hold circuits of each output channel under the control of the clock control signal CLK_SH. The sampling results are amplified and output by the amplifier circuit.

[0078] In the above embodiments, the control method of the MEMS driving circuit is relatively simple and can achieve precise control of the MEMS driving circuit.

[0079] Optionally, the MEMS driving circuit is compatible with the SPI protocol.

[0080] In the above embodiment, because the MEMS driving circuit is compatible with the SPI protocol, the output voltage exhibits monotonicity. The SPI timing diagram of this MEMS driving circuit is as follows: Figure 6 As shown, see Figure 6 DATA_IN is the n-bit (12-bit in the example) digital input to the DAC, CLK_S2P is the input signal clock, CLK_DAC is the DAC conversion clock, CLK_SH is the sample-and-hold circuit clock, and POR is the reset signal.

[0081] See Figure 7 The sample-and-hold circuit is controlled by CLK_SH to sample the output voltage of the DAC module to the input of the high-voltage driver amplifier array, then amplify and output it to drive the MEMS array.

[0082] In this embodiment, the clock signal required by the MEMS driving circuit can be implemented by an off-chip FPGA. The FPGA communicates with the PC via a serial port to control the MEMS driving circuit.

[0083] According to a third aspect of the present invention, an integration method is provided for integrating a MEMS driving circuit as described in the first aspect with a MEMS array, comprising:

[0084] First, the driving circuit, MEMS fixed mirror, optical thin film, and MEMS-CMOS metal interconnect are fabricated using CMOS technology.

[0085] Secondly, SOI technology was used to fabricate wafer-level optical thin films for MEMS devices and to prepare movable structures.

[0086] Secondly, the CMOS wafer and the SOI wafer are bonded together;

[0087] Finally, the back silicon is removed to form a CMOS-MEMS integrated chip.

[0088] In the above embodiments, the MEMS driving circuit can be monolithically integrated with the MEMS array device through back-end processing, featuring high integration, low power consumption, and small and lightweight design, making it suitable for miniaturized spectrometers and other optical shaping systems. This integration method can solve the problems of poor integration, long trace lengths, voltage mismatch, and high power consumption caused by the use of discrete board-level driving for existing MEMS driving circuits and MEMS devices, effectively improving system performance.

[0089] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A MEMS driving circuit, characterized in that, The MEMS-CMOS integrated chip is formed by chip-level integration of the array MEMS driving circuit and the MEMS array using CMOS technology, including: A DAC module and a multiplexing unit are provided. The DAC module is used to convert a given digital signal into an analog voltage signal. The multiplexing unit is connected to the DAC module and is used to split the analog voltage signal output by the DAC module into multiple sub-signals. A sample-and-hold amplifier array, wherein the input terminal of the sample-and-hold amplifier array is connected to the output terminal of the DAC module, and is used to hold the analog voltage signal output by the DAC module; A high-voltage drive amplifier array, the input of which is connected to the output of the sample-and-hold amplifier array, is used to amplify the analog voltage signal output by the DAC module to a preset drive voltage range; the output of the high-voltage drive amplifier array is connected to a MEMS array. A reference voltage source, which is connected to the DAC module, is used to provide a reference voltage to the DAC module; The SPI module, which is connected to the DAC module, is used to transmit external control signals to the internal chip for voltage and timing control.

2. The MEMS driving circuit according to claim 1, characterized in that, Also includes: A buffer is provided, through which the input of the sample-and-hold amplifier array is connected to the output of the DAC module.

3. The MEMS driving circuit according to claim 1, characterized in that, Also includes: The SPI module and the DAC module are connected via registers.

4. The MEMS driving circuit according to claim 1, characterized in that, The reference voltage source is a bandgap reference voltage source.

5. The MEMS driving circuit according to claim 4, characterized in that, The DAC module adopts an R-2R structure.

6. The MEMS driving circuit according to claim 1, characterized in that, The output of the DAC module is connected to the input of the sample-and-hold amplifier array via a unity-gain amplifier.

7. The MEMS driving circuit according to claim 1, characterized in that, The sample-and-hold amplifiers in the sample-and-hold amplifier array are capacitor inverted type structures.

8. The MEMS driving circuit according to claim 1, characterized in that, The high-voltage drive amplifier in the high-voltage drive amplifier array consists of a low-voltage section and a high-voltage section. The low-voltage section is compatible with the output of the sample-and-hold circuit, while the high-voltage section is compatible with the driving voltage required by the MEMS array.

9. A control method for a MEMS driving circuit, characterized in that, Applied to the MEMS driving circuit as described in any one of claims 1 to 8, comprising: The serial input data DATA_IN is converted into n-bit parallel input digital data by a serial-to-parallel converter under the control of the clock CLK_DAC, where n represents the precision of the DAC circuit. The n-bit parallel input digital data is then converted into an analog output level by the DAC module. The analog voltage signal output by the DAC module is sampled sequentially by the sample-and-hold circuits of each output channel under the control of the clock control signal CLK_SH. The sampling results are amplified and output by the amplifier circuit.

10. The control method for the MEMS driving circuit according to claim 9, characterized in that, The MEMS driving circuit is compatible with the SPI protocol.

11. An integration method, characterized in that, For integrating the MEMS driving circuit as described in any one of claims 1 to 8 with a MEMS array, comprising: First, the driving circuit, MEMS fixed mirror, optical thin film, and MEMS-CMOS metal interconnect are fabricated using CMOS technology. Secondly, SOI technology was used to fabricate wafer-level optical thin films for MEMS devices and to prepare movable structures. Secondly, the CMOS wafer and the SOI wafer are bonded together; Finally, the back silicon is removed to form a CMOS-MEMS integrated chip.

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