Flying-law-level adjustable tiny capacitance simulator

Abstract

The present invention relates to the field of electronic information technology, and particularly relates to a femtofarad-level adjustable tiny capacitance simulator, which includes a shielding box, a capacitance simulation structure, a capacitance adjustment structure, and a micrometer structure; the capacitance simulation structure is placed on the bottom plate of the shielding box and receives an excitation signal from an external device; the micrometer structure supports the capacitance adjustment structure directly above the capacitance simulation structure and changes the facing area between the capacitance adjustment structure and the capacitance simulation structure. The capacitance adjustment structure is electrically connected to the capacitance simulation structure to form a first capacitance; the first capacitance forms a capacitance difference with a second capacitance in the capacitance simulation structure, and the capacitance difference is transmitted out of the shielding box. By adjusting the facing area between the capacitance adjustment structure and the capacitance simulation structure through the micrometer structure, the relative area between the electrodes of the first capacitance is changed, thereby achieving femtofarad-level capacitance change, and further meeting the requirements of adjustable, accurate, and stable femtofarad-level capacitance difference input for the capacitance sensing circuit in a precision electronic measurement system.

Description

Technical Field

[0001] The present invention belongs to the field of electronic information technology, and particularly relates to a femtofarad-level adjustable tiny capacitance simulator. Background Art

[0002] The femtofarad-level adjustable tiny capacitance simulator is mainly used to simulate variable femtofarad-level tiny capacitance changes (10 -15 magnitude), and can provide a continuously variable tiny capacitance difference input for the capacitance sensing circuit in a precision electronic measurement system to verify the functions and performance of the circuit itself. The capacitance sensing circuit measures the physical quantity to be measured by measuring the change in tiny capacitance. Therefore, during the test and debugging process of the capacitance sensing circuit, a tiny capacitance that is easy to adjust is usually required as the input signal of the capacitance sensing circuit. The input capacitance of the capacitance sensing circuit should have the capabilities and characteristics of accurate capacitance value, stability, variability, easy adjustment, and good repeatability.

[0003] There are two common capacitance sensing inputs. The first is a capacitor with a fixed capacitance value, such as a thin-film capacitor, a ceramic capacitor, etc. However, the current capacitors cannot achieve an accurate femtofarad magnitude, and the capacitance value is fixed, which is not suitable for the requirement that the input capacitance often changes during the test process. The second is a parallel-plate capacitor with an air medium formed by parallel copper plates. This capacitor has insurmountable edge effects, that is, the electric field lines become denser near the edges of the electrodes, resulting in a larger electric field intensity at the edges than in the central region. This will cause uneven charge distribution in the edge region, thereby affecting the overall performance of the capacitor. At the same time, its capacitance adjustment method depends on the change in the distance between the parallel copper plates, and it will bring additional electromagnetic interference to the precision capacitance sensing circuit through an active PI (Proportional-Integral) control component, affecting the detection accuracy. The poor accuracy of the component itself affects the overall repeatability of the simulator itself. Summary of the Invention

[0004] In view of this, the present invention aims to provide a femtofarad-level adjustable tiny capacitance simulator, which adjusts the facing area between the capacitance adjustment structure and the capacitance simulation structure in a micrometer structure, equivalent to changing the relative area between the electrodes of the first capacitor, to complete femtofarad-level capacitance changes, and further meet the adjustable, accurate, and stable femtofarad-level capacitance difference requirements for the input of the capacitance sensing circuit in a precision electronic measurement system.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows:

[0006] A fly-level adjustable tiny capacitance simulator, comprising a shielding box, a capacitance simulation structure and a capacitance adjustment structure located inside the shielding box, and a micrometer structure located on the side wall of the shielding box; wherein, the capacitance simulation structure is placed on the bottom plate of the shielding box and receives an excitation signal from an external device; the micrometer structure supports the capacitance adjustment structure directly above the capacitance simulation structure and changes the facing area between the capacitance adjustment structure and the capacitance simulation structure, the capacitance adjustment structure is conducted with the capacitance simulation structure to form a first capacitance; the first capacitance forms a capacitance difference with a second capacitance in the capacitance simulation structure, and transmits the capacitance difference out of the shielding box.

[0007] Further, the capacitance simulation structure includes a central capacitance circuit, a capacitance pole piece and a circuit support member; wherein, the circuit support member insulatively supports the central capacitance circuit on the bottom plate; the central capacitance circuit includes a cascaded first capacitance group and a second capacitance group, and a power supply wire for receiving an excitation signal is connected to the center connection of the first capacitance group and the second capacitance group; the structures of the first capacitance group and the second capacitance group are the same, and both are composed of no less than 2 capacitors in cascade; the micrometer structure supports the capacitance adjustment structure directly above the first capacitance group and changes the facing area between the capacitance adjustment structure and the first capacitance group, the capacitance adjustment structure is conducted with the first capacitance group to form a first capacitance; the capacitance pole piece is conducted with the second capacitance group to form a second capacitance.

[0008] Further, the capacitance pole piece is an L-shaped copper sheet, one end of the copper sheet is welded to the end of the second capacitance group far from the first capacitance group and is conducted with the second capacitance group, and the other end of the copper sheet faces the second capacitance group, so that the second capacitance group and the copper sheet form a second capacitance.

[0009] Further, the capacitance adjustment structure includes a capacitance pole bar and a pole bar connecting member; wherein, the pole bar connecting member fixedly connects one end of the capacitance pole bar to the micrometer structure, so that the micrometer structure drives the capacitance pole bar to move, thereby changing the facing area between the capacitance pole bar and the first capacitance group; the micrometer structure is conducted with the end of the first capacitance group far from the second capacitance group through a wire, so that the first capacitance group is conducted with the capacitance pole bar to form a first capacitance.

[0010] Further, the capacitance pole bar is a copper bar with a tolerance less than ±0.01 mm.

[0011] Further, the micrometer structure includes a micrometer, a micrometer support platform and a micrometer support member; wherein, the micrometer support member insulatively supports the micrometer support platform on the bottom plate, the micrometer is embedded in the side wall and supported by the micrometer support platform; the micrometer support platform is conducted with the end of the first capacitance group far from the second capacitance group through a wire; the micrometer is coaxially and fixedly connected to the capacitance pole bar through the pole bar connecting member, so that the micrometer drives the capacitance pole bar to move.

[0012] Further, an excitation signal input terminal is provided on the outer side wall of the shielding box. The excitation signal input terminal is connected to a power supply wire, enabling an external device to provide an excitation signal to the capacitance simulation structure through the excitation signal input terminal. Two capacitance signal output terminals are provided on the outer side wall of the shielding box. The two capacitance signal output terminals are respectively connected to the capacitance pole piece and the pole bar connector through wires to output a capacitance difference.

[0013] Further, the shielding box is an aluminum metal shell.

[0014] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0015] (1) The femtofarad-level adjustable micro-capacitance simulator of the present invention adjusts the facing area between the capacitance adjustment structure and the capacitance simulation structure through a micrometer structure, which is equivalent to changing the relative area between the electrodes of the first capacitance, completing femtofarad-level capacitance change and capacitance difference adjustment, and further meeting the adjustable, accurate, and stable femtofarad-level capacitance difference requirements input by the capacitance sensing circuit in the precision electronic measurement system;

[0016] (2) For the capacitance pole bar used for one side electrode of the first capacitance and the capacitance pole piece used for one side electrode of the second capacitance in the present invention, the capacitance pole bar and the capacitance pole piece are small in size, have weak edge effect influence, and low noise, and can well reflect the performance of the capacitance sensing circuit itself. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 is a perspective structural schematic diagram of the femtofarad-level adjustable micro-capacitance simulator described in the embodiment of the present invention;

[0019] Figure 2 is an internal structural schematic diagram of the femtofarad-level adjustable micro-capacitance simulator described in the embodiment of the present invention;

[0020] Figure 3 is a circuit structural schematic diagram of the femtofarad-level adjustable micro-capacitance simulator described in the embodiment of the present invention.

[0021] Description of the reference numerals:

[0022] 1. Shielding box; 2. Capacitance simulation structure; 201. First capacitor group; 202. Second capacitor group; 203. Capacitor; 204. Capacitor electrode plate; 205. Circuit support member; 3. Capacitance adjustment structure; 301. Capacitance pole bar; 302. Pole bar connecting member; 4. Micrometer structure; 401. Micrometer; 402. Micrometer support platform; 403. Micrometer support member; 5. Excitation signal input terminal; 6. Capacitance signal output terminal. Detailed implementation manners

[0023] In order to make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the present invention in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0024] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0025] In the description of the present invention, it should be understood that the orientation or positional relationships indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0026] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0027] The following will elaborate on the present invention in detail with reference to the accompanying drawings and embodiments.

[0028] As Figures 1 to 3As shown in the figure, the femto - level adjustable micro - capacitance simulator described in the embodiment of the present invention includes a shielding box 1, a capacitance simulation structure 2, a capacitance adjustment structure 3, and a micrometer structure 4. Among them, the capacitance simulation structure 2 is placed on the bottom plate of the shielding box 1, the micrometer structure 4 is placed on the side wall of the shielding box 1, and the micrometer structure 4 supports the capacitance adjustment structure 3 directly above the capacitance simulation structure 2. The capacitance simulation structure 2 is electrically connected to the capacitance adjustment structure 3 to form a first capacitance. The first capacitance forms a capacitance difference with the second capacitance in the capacitance simulation structure 2, and the capacitance difference is transmitted out of the shielding box 1. The micrometer structure 4 changes the overlapping area between the capacitance adjustment structure 3 and the capacitance simulation structure 2, so that the capacitance value of the first capacitance changes, thereby adjusting the output capacitance difference.

[0029] In the embodiment of the present invention, in order to shield the electromagnetic wave interference in the space of the capacitance simulation structure 2 and the capacitance adjustment structure 3 and avoid introducing noise, it is preferably to use an aluminum metal shell as the shielding box 1.

[0030] An excitation signal input terminal 5 is provided on the outer side wall of the shielding box 1. The excitation signal input terminal 5 is connected to the capacitance simulation structure 2, so that an external device provides an excitation signal to the capacitance simulation structure 2 through the excitation signal input terminal 5. Two capacitance signal output terminals 6 are provided on the outer side wall of the shielding box 1 opposite to the excitation signal input terminal 5. The two capacitance signal output terminals 6 are respectively connected to the capacitance simulation structure 2 and the capacitance adjustment structure 3 through wires to form and output a capacitance difference.

[0031] The capacitance simulation structure 2 includes a central capacitance circuit, a capacitance electrode plate 204, and a circuit support member 205. Among them, the central capacitance circuit includes a cascaded first capacitor group 201 and a second capacitor group 202. The structures of the first capacitor group 201 and the second capacitor group 202 are the same, and both are composed of no less than 2 capacitors 203 in cascade. The excitation signal input terminal 5 is connected to the cascaded part of the first capacitor group 201 and the second capacitor group 202 through a power supply wire, so that the excitation signal is sequentially input to the first capacitor group 201 and the second capacitor group 202 through the excitation signal input terminal 5 and the power supply wire.

[0032] The capacitance electrode plate 204 is electrically connected to the second capacitor group 202, so that the capacitance electrode plate 204 and the second capacitor group 202 form a second capacitance. The capacitance electrode plate 204 is connected to one of the capacitance signal output terminals 6 through a wire. The circuit support member 205 insulates and supports the central capacitance circuit on the bottom plate of the shielding box 1.

[0033] In an embodiment of the present invention, preferably, six capacitors 203 are cascaded to form a first capacitor group 201 and a second capacitor group 202 respectively, and the first capacitor group 201 and the second capacitor group 202 are symmetrically distributed along a straight line direction and welded on a PCB (Printed Circuit Board) to form a central capacitor circuit. The capacitor pole piece 204 is an L-shaped copper sheet. One end of the copper sheet is welded to one end of the second capacitor group 202 far from the first capacitor group 201 and is electrically connected to the second capacitor group 202. The other end of the copper sheet faces the second capacitor group 202, so that the other end of the copper sheet forms a second parasitic capacitor with the wire in the second capacitor group 202. At this time, the second capacitor group 202 and the second parasitic capacitor together form a second capacitor. To prevent the back solder joints of the central capacitor circuit from being electrically connected to the shielding box 1, the circuit support member 205 includes but is not limited to a single insulating support pad such as a rubber cushion block, and structures with adjustable height such as a micro lifting table and a slide rail of a slider, to achieve height matching with the capacitor adjustment structure 3. In an embodiment of the present invention, the circuit support member 205 is a single rubber cushion block with a certain height. When it is necessary to adjust the height of the central capacitor circuit, different height rubber cushion blocks can be replaced.

[0034] The capacitor adjustment structure 3 includes a capacitor pole rod 301 and a pole rod connecting member 302. Among them, the pole rod connecting member 302 fixedly connects one end of the capacitor pole rod 301 to the micrometer structure 4, so that the micrometer structure 4 drives the capacitor pole rod 301 to move, thereby changing the facing area between the capacitor pole rod 301 and the first capacitor group 201. The micrometer structure 4 is electrically connected to one end of the first capacitor group 201 far from the second capacitor group 202 through a wire. At this time, the capacitor pole rod 301 and the wire in the first capacitor group 201 form a first parasitic capacitor. At this time, the first capacitor group 201 and the first parasitic capacitor together form a first capacitor. When the facing area between the capacitor pole rod 301 and the first capacitor group 201 is changed, the size of the first parasitic capacitor changes, thereby changing the capacitance value of the first capacitor.

[0035] In an embodiment of the present invention, to ensure consistency with the capacitor simulation structure 2, the capacitor pole rod 301 is preferably made of a copper rod with a tolerance of less than ±0.01 mm, and the capacitor pole rod 301 is placed parallel to the first capacitor group 201.

[0036] The micrometer structure 4 includes a micrometer 401, a micrometer support platform 402, and a micrometer support member 403. Among them, the micrometer support member 403 insulatively supports the micrometer support platform 402 on the bottom plate of the shielding box 1, and the micrometer 401 is embedded in the side wall of the shielding box 1 and supported by the micrometer support platform 402. The micrometer 401 is coaxially and fixedly connected to the capacitance pole 301 via a pole bar connector 302, so that the micrometer 401 drives the capacitance pole 301 to move. The micrometer support platform 402 is connected to another capacitance signal output terminal 6 through a wire, so that the capacitance pole 301 and the first capacitance group 201 form a first capacitance, and the two capacitance signal output terminals 6 output the capacitance difference between the first capacitance and the second capacitance.

[0037] In the embodiment of the present invention, to avoid introducing additional noise that affects the accuracy of the output capacitance difference, the micrometer 401 and the micrometer support platform 402 are preferably made of non-metallic materials. And to enable the micrometer support platform 402 to fully support the micrometer 401 while ensuring that the movement of the micrometer 401 is not affected, the micrometer support platform 402 is preferably of a Y-shaped structure and the micrometer 401 is placed on the micrometer support platform 402. At the same time, balls are added between the micrometer 401 and the micrometer support platform 402 to reduce the friction between the two. To avoid the micrometer 401 and the micrometer support platform 402 from being electrically connected to the shielding box 1, in the embodiment of the present invention, the micrometer support member 403 is a single insulating rubber pad.

[0038] When the structure of the capacitance simulation structure 2 is determined, the second capacitance C2 formed by the capacitance pole piece 204 and the second capacitance group 202 remains unchanged, and the magnitude of the first capacitance C1 composed of the first capacitance group 201 and the capacitance pole 301 is changed by rotating the micrometer 401 to change the facing area ΔA between the capacitance pole 301 and the first capacitance group 201, that is:

[0039]

[0040] where ε0 represents the permittivity of free space, ε r represents the relative permittivity of the medium, and d represents the distance between a capacitance group 201 and the capacitance pole 301.

[0041] When an external device provides an excitation signal to the excitation signal input terminal 5, the capacitance pole piece 204 and the pole bar connector 302 output the first capacitance C1 and the second capacitance C2 to the two capacitance signal output terminals 6 and constitute a capacitance difference ΔC as:

[0042] ΔC = |C1 - C2|.

[0043] The range, resolution of the femtofarad-level adjustable micro-capacitance simulator provided by the embodiments of the present invention are related to the size of the capacitance pole 301, the distance between the capacitance pole 301 and the first capacitor bank 201, the range and resolution of the micrometer 401. In the embodiments of the present invention, the diameter of the capacitance pole 301 is 10 ± 0.01 mm, the length is 50 mm, the distance between the capacitance pole 301 and the first capacitor bank 201 is 1.6 cm, the range of the micrometer 401 is 13 mm, the resolution of the micrometer 401 is 0.01 mm, and the range of the femtofarad-level adjustable micro-capacitance simulator obtained is about 40 fF, and the resolution is 0.4 fF. Rotate the micrometer 401 to the same position repeatedly for multiple times, and the measurement result of the simulator stability is less than ±0.05 fF. It can be seen that the femtofarad-level adjustable micro-capacitance simulator provided by the present invention can achieve femtofarad-level capacitance adjustment and output.

[0044] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A femtofarad-level adjustable micro-capacitance simulator, comprising a shielding box, characterized in that: It also includes a capacitance simulation structure and a capacitance adjustment structure located inside the shielding box, and a micrometer structure located on the side wall of the shielding box; wherein the capacitance simulation structure is placed on the bottom plate of the shielding box and receives an excitation signal from an external device; the micrometer structure supports the capacitance adjustment structure directly above the capacitance simulation structure and changes the directly facing area between the capacitance adjustment structure and the capacitance simulation structure, the capacitance adjustment structure is connected to the capacitance simulation structure and forms a first capacitance; the first capacitance forms a capacitance difference with a second capacitance in the capacitance simulation structure, and the capacitance difference is transmitted out of the shielding box; The capacitor simulation structure includes a central capacitor circuit, a capacitor electrode and a circuit support; wherein the circuit support insulates and supports the central capacitor circuit on the bottom plate; the central capacitor circuit includes a cascaded first capacitor group and a second capacitor group, and a power supply wire for receiving the excitation signal is connected at the central connection between the first capacitor group and the second capacitor group; the first capacitor group and the second capacitor group have the same structure, and both are composed of no less than two cascaded capacitors; the micrometer structure supports the capacitor adjustment structure directly above the first capacitor group and changes the facing area of ​​the capacitor adjustment structure and the first capacitor group, the capacitor adjustment structure is connected to the first capacitor group to form the first capacitor; the capacitor electrode is connected to the second capacitor group to form the second capacitor.

2. The femtofarad-level adjustable micro-capacitor simulator according to claim 1, characterized in that: The capacitor electrode is an L-shaped copper sheet, one end of which is welded to an end of the second capacitor group away from the first capacitor group and is conductive with the second capacitor group, and the other end of the copper sheet faces the second capacitor group, so that the second capacitor group and the copper sheet form the second capacitor.

3. The femtofarad-level adjustable micro-capacitor simulator according to claim 1, characterized in that: The capacitance adjustment structure includes a capacitor electrode and a electrode connector; wherein the electrode connector fixes one end of the capacitor electrode to the micrometer structure, so that the micrometer structure drives the capacitor electrode to move, thereby changing the facing area between the capacitor electrode and the first capacitor group; the micrometer structure is connected to one end of the first capacitor group away from the second capacitor group through a wire, so that the first capacitor group is connected to the capacitor electrode and forms the first capacitor.

4. The femtofarad-level adjustable micro-capacitor simulator according to claim 3, characterized in that: The capacitor pole is a copper rod with a tolerance less than ±0.01 mm.

5. The femtofarad-level adjustable micro-capacitor simulator according to claim 3, characterized in that: The micrometer structure includes a micrometer, a micrometer support platform and a micrometer support member; wherein, the micrometer support member insulates and supports the micrometer support platform on the bottom plate, and the micrometer is embedded in the side wall and supported by the micrometer support platform; the micrometer support platform is connected to the end of the first capacitor group away from the second capacitor group through a wire; the micrometer is coaxially fixed to the capacitor pole via the pole connector, so that the micrometer drives the capacitor pole to move.

6. The femtofarad-level adjustable micro-capacitor simulator according to claim 3, characterized in that: An excitation signal input terminal is provided on the outer side wall of the shielding box, and the excitation signal input terminal is connected to the power supply wire, so that the external device provides the excitation signal to the capacitor simulation structure through the excitation signal input terminal; two capacitance signal output terminals are provided on the outer side wall of the shielding box, and the two capacitance signal output terminals are respectively connected to the capacitor electrode and the electrode connecting piece through wires to output the capacitance difference.

7. The femtofarad-level adjustable micro-capacitor simulator according to claim 1, characterized in that: The shielding box is an aluminum metal shell.

Images