Programmable capacitance output device

Abstract

The application provides a program-controlled capacitance output device, which comprises a processor circuit, a driving circuit, a first relay group, a capacitance group, a second relay group and a communication and interface circuit connected in sequence, the processor circuit is connected with the communication and interface circuit, the communication and interface circuit is connected with host computer software and a product to be tested, and the driving circuit is connected with the second relay group; the output end of each capacitance in the capacitance group can output three capacitance values through the on-off setting of a relay, and the specified capacitance output value in the specified capacitance range and the specified capacitance difference interval can be obtained by adjusting the capacitance value of each capacitance. The application has the multiple capacitance input capacity for the segmented capacitance transformer with different ranges, meets the test requirements in various test scenes such as aging, temperature cycle and vibration when the transformer is batched, and can maximize the saving of test resources and test cost.

Description

Technical Field

[0001] This invention relates to the field of electrical components technology, and more specifically to a programmable capacitor output device. Background Technology

[0002] Sensors based on the segmented capacitance measurement principle suffer from environmental limitations, resulting in the separation of the front-end sensitive capacitor module and the back-end capacitance measurement and conversion circuit. This means the front-end sensitive capacitor module cannot simultaneously undergo various tests with the back-end capacitance measurement and conversion circuit, or if tests can be performed simultaneously, multiple operating conditions cannot be tested. Currently, fixed capacitor banks are bulky, slow to operate, and offer a limited number of capacitor inputs, failing to meet the multi-channel capacitance input requirements of mass-produced sensors.

[0003] Therefore, there is a need for an analog front-end sensitive capacitor module that can provide variable inputs to the back-end capacitance measurement conversion circuit and evaluate its functional performance. Summary of the Invention

[0004] This invention aims to solve the testing problem of sensors based on the segmented capacitance measurement principle. It provides a programmable capacitance output device that can provide multiple sets of capacitance inputs for segmented capacitance converters with different ranges. This meets the testing needs of various testing scenarios such as aging, temperature cycling, and vibration when converters are mass-produced, and can save testing resources and experimental costs to the greatest extent.

[0005] This invention provides a programmable capacitor output device, comprising a processor circuit, a drive circuit, a first relay group, a capacitor group, a second relay group, and a communication and interface circuit connected in sequence. The processor circuit is connected to the communication and interface circuit, which is connected to host computer software and the product under test. The drive circuit is connected to the second relay group.

[0006] The capacitor bank includes at least two capacitors connected in parallel, the output terminal includes terminal 1, terminal 2 and common terminal, and the first relay bank includes at least two relays;

[0007] The number of relays in the first relay group is twice the number of capacitors in the capacitor group. One end of each capacitor is connected to terminals 1 and 2 through two relays in the first relay group, and the other end is connected to the common terminal. The output terminal of each capacitor in the capacitor group can output three capacitance values ​​through the on / off setting of the relays. By adjusting the capacitance value of each capacitor, any capacitance output value within a specified capacitance difference interval can be obtained within a specified capacitance range.

[0008] The processor circuit receives signals from the host computer and sends control signals to the drive circuit through the I / O port. The drive circuit controls the corresponding relay in the first relay group to control the output capacitance value of the capacitor group. The drive circuit selects the corresponding relay in the second relay group and controls the drive circuit to select the external coaxial contact of the corresponding product to provide output capacitance for the external product.

[0009] In a preferred embodiment of the programmable capacitor output device described in this invention, the capacitor bank comprises capacitors with capacitance values ​​of C1, ..., C1, ..., C2. i ..., C n There are n fixed-value capacitors. Each capacitor is controlled by two relays in the first relay group to control the output capacitor between terminal 1 and the common terminal, and the output capacitor between the common terminal and terminal 2.

[0010] The output capacitance ΔC of the capacitor bank is the coefficient k of each fixed capacitor. i With capacitance C i The product of the two, with a capacity C i To balance ternary numbers The product of the required output capacitor difference interval g, k i ∈{-1,0,1}.

[0011] The programmable capacitor output device described in this invention, as a preferred embodiment,

[0012]

[0013] Among them, C 奇 C is the capacitance between terminal 1 and the common terminal of the capacitor bank. 偶 This is the capacitance value between terminals 2 and the common terminal of the capacitor bank;

[0014]

[0015] Among them, C max This represents the maximum value required for △C.

[0016] In the programmable capacitor output device of the present invention, as a preferred embodiment, g can be as low as 0.1pF;

[0017] k i When the value is -1, the relay connected to terminal 1 is disconnected, and the relay connected to terminal 2 is closed;

[0018] k i When the value is 0, both the relay connected to terminal 1 and the relay connected to terminal 2 are disconnected;

[0019] k i When the value is 1, the relay connected to terminal 1 is closed, and the relay connected to terminal 2 is open.

[0020] In a preferred embodiment of the programmable capacitor output device of the present invention, the number of communication and interface circuits is at least two, and each communication and interface circuit includes an output terminal 1, an output common terminal and an output terminal 2.

[0021] The second relay group includes m relay groups connected in parallel. Each relay group includes a 1-terminal relay, a common-terminal relay, and a 2-terminal relay connected in parallel, with capacitor C0 connected between the 1-terminal relay and the common-terminal relay, and between the common-terminal relay and the 2-terminal relay, respectively.

[0022] One-terminal relay connects one end to terminal 1 of the capacitor bank and the other end to terminal 1 of the output. Common-terminal relay connects one end to the common terminal of the capacitor bank and the other end to the common terminal of the output. Two-terminal relay connects one end to terminal 2 of the capacitor bank and the other end to terminal 2 of the output.

[0023] When there is no capacitor output, capacitor C0 can determine the state of the product under test.

[0024] In a preferred embodiment of the programmable capacitor output device of the present invention, the processor circuit includes a processor chip and peripheral clock, power conversion and programming interface circuits; the drive circuit includes a multiplexer chip and a driver chip.

[0025] The communication and interface circuits include RS422 or RS485 serial communication interface circuits, Ethernet interface circuits, and coaxial connectors.

[0026] The relays in both the first and second relay groups are reed relays.

[0027] Each capacitor in the capacitor bank has a different capacitance value, and the ratio of two adjacent capacitance values ​​is 3.

[0028] The printed circuit boards of the processor circuit, the driver circuit, the first relay group, the capacitor group, the second relay group, and the coaxial connectors of the communication and interface circuit are all shielded to ground.

[0029] The programmable capacitor output device of the present invention, as a preferred embodiment, has at least two capacitor banks to provide capacitors with different capacitance ranges and capacitance difference intervals for the product under test;

[0030] Each capacitor bank is connected to a communication and interface circuit via a second relay bank, and the communication and interface circuit has at least one output.

[0031] The programmable capacitor output device of the present invention, as a preferred embodiment, is used in any of the following test scenarios: batch aging test, temperature cycling test, or vibration test of a sensor based on the segmented capacitance measurement principle.

[0032] Before testing, the number of capacitors n and the fixed capacitance value of each capacitor in the capacitor bank are obtained by using the required capacitance difference interval g and the required capacitance range. The capacitor bank is then built and assembled to obtain the programmable capacitor output device.

[0033] During testing, the product under test is connected to the communication and interface circuit, and the host computer software controls the on / off state of the first relay group to provide the required test capacitance to the product under test.

[0034] In a preferred embodiment of the programmable capacitor output device described in this invention, when two or more products to be tested are subjected to batch aging tests or temperature cycling tests, all products to be tested are connected to communication and interface circuits and then placed into batch aging test equipment or temperature cycling test equipment. When performance testing is required during aging tests or temperature cycling tests, the host computer software controls the on / off state of the first relay group and the second relay group respectively to provide the required test capacitors for the products to be tested.

[0035] In a preferred embodiment of the programmable capacitor output device described in this invention, when the specified capacitance difference intervals of the products under test are different or the capacitance ranges are incompatible, the programmable capacitor output device is equipped with at least two capacitor groups. After all the products under test are connected to the communication and interface circuits respectively, they are placed into the batch aging test equipment or the temperature cycling test equipment. When performance testing is required during the aging test or the temperature cycling test, the host computer software controls the on / off state of the first relay group and the second relay group respectively to provide different specified capacitance difference intervals and capacitance ranges for the products under test.

[0036] The analog capacitor output of the aforementioned segmented capacitor converter has a three-terminal configuration: "Terminal 1", "Common Terminal", and "Terminal 2". A capacitor C needs to be input between "Terminal 1" and "Common Terminal". 奇 A capacitor C needs to be input between the "terminal 2" and the "common terminal". 偶 C 奇 The capacitance value and C 偶 The difference in capacitance needs to be ±C max The changes between them.

[0037] The present invention has the following advantages:

[0038] (1) This invention can provide input capacitors for multiple segmented capacitor principle products with the same or different ranges, and can also provide a single fixed value capacitor or multiple fixed value capacitors for multiple segmented capacitor principle products at the same time, which can adapt to the application scenario of needing capacitor input for long-term power-on testing.

[0039] (2) This invention can communicate with the host computer via serial port or network port, and can programmatically switch multiple capacitors with different fixed values ​​and output to multiple products in a time-sharing manner.

[0040] (3) The present invention can provide ground shielding from capacitors, reed relay switches, printed circuit boards to coaxial connectors, which can eliminate the influence of inter-circuit interference and distributed capacitance on test accuracy, and the minimum interval between the two output capacitors is 0.1pF.

[0041] (4) The present invention has the ability to provide multiple sets of capacitor inputs for segmented capacitor converters with different ranges, which can meet the testing needs of various test scenarios such as aging, temperature cycling and vibration when the converter is mass-produced, and can save test resources and test costs to the greatest extent. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of a programmable capacitor output device.

[0043] Figure 2 A schematic diagram of a single capacitor control circuit for a programmable capacitor output device;

[0044] Figure 3 This is a schematic diagram of a single-group capacitor control circuit for a programmable capacitor output device.

[0045] Figure 4 This is a schematic diagram of a single-group capacitor output gating control circuit for a programmable capacitor output device.

[0046] Figure label:

[0047] 1. Processor circuit; 2. Drive circuit; 3. First relay group; 4. Capacitor group; 5. Second relay group; 51. Relay group; 511. 1-terminal relay; 512. Common terminal relay; 513. 2-terminal relay; 6. Communication and interface circuit. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0049] Example 1

[0050] like Figures 1-3 As shown, a programmable capacitor output device includes a processor circuit 1, a drive circuit 2, a first relay group 3, a capacitor group, a second relay group 5, and a communication and interface circuit 6.

[0051] Processor circuit 1 includes a processor chip and peripheral clock, power conversion, and programming interface circuits. Communication and interface circuit 6 includes an RS422 or RS485 serial communication interface circuit, an Ethernet interface circuit, and a coaxial connector. Drive circuit 2 includes a multiplexer chip and a driver chip, which control the switching on and off of the reed relays in the first reed relay group 3 and the second reed relay group 5.

[0052] The processor circuit 1 receives signals from the host computer and sends control signals to the drive circuit 2 through the I / O port. The drive circuit 2 is controlled to select the corresponding relay in the first relay group 3 to control the output capacitance value. The drive circuit 1 is also controlled to select the corresponding relay in the second relay group 5 and to select the external coaxial contact of the corresponding product to provide output capacitance for the external product.

[0053] Each capacitor bank 4 consists of multiple fixed-value capacitors. Each capacitor bank 4 consists of n fixed-value capacitors with capacitance values ​​C1, C2, ..., Cn. Each fixed-value capacitor is controlled by two switches. The on / off state of the two switches determines the coefficient of the capacitor, which is one of {-1, 0, 1}.

[0054] The first relay group 3 is a reed relay, used to switch the capacitors in the capacitor group on and off with "terminal 1" and "terminal 2".

[0055] The second relay group 5 is a reed relay, used to select the on / off state of the corresponding points of the coaxial connectors of n products, namely the "1", "common" and "2" terminals, and the "1", "common" and "2" terminals of the capacitor group.

[0056] The second relay group 5 includes m relay groups 51 connected in parallel. Each relay group 51 includes a 1-terminal relay 511, a common-terminal relay 512, and a 2-terminal relay 513 connected in parallel, and a capacitor C0 connected between the 1-terminal relay 511 and the common-terminal relay 512, and between the common-terminal relay 512 and the 2-terminal relay 513, respectively.

[0057] One-terminal relay 511 is connected to one end of capacitor bank 4 and the other end is connected to output terminal 1. Common terminal relay 512 is connected to the common terminal of capacitor bank 4 and the other end is connected to the common terminal of output terminal. Two-terminal relay 513 is connected to one end of capacitor bank 4 and the other end is connected to output terminal 2.

[0058] Each capacitor bank consists of multiple fixed-value capacitors. Each capacitor bank has capacitors with capacitance values ​​of C1, ..., C10 ... i ...C n It consists of n fixed-value capacitors.

[0059] Each capacitor bank has 4 outputs "C" 奇 The capacitance value of "C" and "C" 偶 The difference in capacitance values ​​is as follows:

[0060]

[0061] Ci = g * 3 (i-1) (2)

[0062] Where: g represents the interval of the required output capacitance difference. For example, the interval of 0.1, 0.2......0.7, 0.8 is 0.1; the interval of 1, 2......7, 8 is 1; and the interval of 10, 20......70, 80 is 10.

[0063] It is a balanced ternary number.

[0064] ki∈{-1,0,1} represents the coefficient of each fixed-value capacitor.

[0065] If you need to output △C(C) 奇 -C 偶 The value of C is between -120 pF and +120 pF, with an interval of 1 pF. 奇 and C 偶 Capacitors. The required number of capacitors, n, can be determined as 5 using Formula 3. Formula 2 determines the values ​​of the 5 fixed capacitors to be 1pF, 3pF, 9pF, 27pF, and 81pF.

[0066]

[0067] Using these 5 fixed-value capacitors, and combining the coefficient k of each fixed-value capacitor, it is possible to achieve any value of ΔC among -120pF, -119pF, -118pF...119pF, 120pF.

[0068] If you need to output the value of ΔC between -100pF and +100pF, with intervals of 0.1pF, then... 奇 and C 偶 Capacitors. The required number of capacitors, n, can be determined using Formula 3, which gives n as 7. Formula 2 determines the values ​​of the 7 fixed capacitors to be 0.1pF, 0.3pF, 0.9pF, 2.7pF, 8.1pF, 24.3pF, and 72.9pF.

[0069] Using these 7 fixed-value capacitors, and combining the coefficient k of each fixed-value capacitor, ΔC can be achieved for any value among -100pF, -99.9pF, -99.8pF, ..., 99.9pF, and 100pF.

[0070] If you need to output the value of ΔC between -1000pF and +1000pF, with intervals of 10pF, then... 奇 and C 偶 Capacitors. The required number of capacitors, n, can be determined as 5 using Formula 3. Formula 2 determines the values ​​of the 5 fixed capacitors to be 10pF, 30pF, 90pF, 270pF, and 810pF.

[0071] Using these 5 fixed-value capacitors, and combining the coefficient k of each fixed-value capacitor, it is possible to achieve any value of ΔC among -1000pF, -990pF, -980pF...990pF, and 1000pF.

[0072] In this embodiment, ground shielding is provided for capacitors, reed relay switches, printed circuit boards and coaxial connectors, which can eliminate the impact of inter-path interference and distributed capacitance on test accuracy.

[0073] like Figure 2 As shown, in a single capacitor control circuit, the on / off state of two switches is controlled by a relay to achieve the coefficient k in formula 1. i The function is shown in Table 1. The correspondence between the coefficient values ​​and the on / off state of the switch is shown in Table 1.

[0074] Table 1. Implementation methods for a single capacitance coefficient

[0075] Serial Number coefficient K1 state K2 state 1 -1 disconnect closure 2 0 disconnect disconnect 3 1 closure disconnect

[0076] like Figure 3 As shown, the "1", "common", and "2" terminals of multiple capacitor control circuits are connected together to form a capacitor bank. The final output capacitance of this capacitor bank, consisting of "1" and "common", is C. 奇 The final output capacitor for the "2-terminal" and "common terminal" is "C". 偶 C 奇 -C 偶 The value can be calculated using Formula 1.

[0077] like Figure 4 As shown, in the single-group capacitor control circuit, the currently tested product is selected through the gating and driving circuit, and the "C" output of the group capacitor is controlled. 奇 "and "C 偶 "The capacitor output is given to the currently tested product. The output capacitor C0 is used to determine the product's state when the second relay group of the current product is not activated, preventing the product from operating under uncertain conditions. At this time, the balanced ternary capacitor C..." 奇 and C 偶 It is not output to the current product.

[0078] When there is no capacitor input, determine the product status.

[0079] The first relay group 3 can use balanced ternary to enable the capacitor group 4 to output C0 and many different fixed values ​​C. j These two capacitors can be used as inputs for testing many products with the same measurement range. For example... Figure 4 In the implementation shown, all three switches KA11, KA12, and KA13 of KA1 are on, while the other switches of KAx are off, thus setting C above. jC0 has provided input for product A1, and at this time, input for other products is disconnected.

[0080] The fixed-value capacitors C1, C2...Cn mentioned in this invention can be implemented using one capacitor or multiple capacitors connected in parallel.

[0081] During aging tests or temperature cycling tests, each product normally uses two C0 inputs, and the product is in a zero-position state, requiring only fixed capacitors to prevent interference from affecting internal components. During aging tests, a programmable capacitor output device is used to input different capacitance values ​​to each product to test its linearity performance. Products are tested sequentially, and only one product of the same type is tested at a time.

[0082] The products are tested alternately after a period of high-temperature or low-temperature temperature cycling. During each product test, a different input capacitor is switched using a programmable capacitor output device. At other times, the capacitor is not switched; only the two C0 values ​​are used as input.

[0083] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A programmable capacitor output device, characterized in that: The device includes a processor circuit (1), a drive circuit (2), a first relay group (3), a capacitor group (4), a second relay group (5), and a communication and interface circuit (6) connected in sequence. The processor circuit (1) is connected to the communication and interface circuit (6), which is connected to the host computer software and the product under test. The drive circuit (2) is connected to the second relay group (5). The capacitor bank (4) includes at least two capacitors connected in parallel, and the output terminal includes terminal 1, terminal 2 and common terminal. The first relay bank (3) includes at least two relays. The number of relays in the first relay group (3) is twice the number of capacitors in the capacitor group (4). One end of each capacitor is connected to end 1 and end 2 through two relays in the first relay group (3), and the other end is connected to the common end. The output terminal of each capacitor in the capacitor group (4) can output three capacitance values ​​through the on / off setting of the relays. By adjusting the capacitance value of each capacitor, any capacitance output value within a specified capacitance difference interval can be obtained within a specified capacitance range. The processor circuit (1) receives signals from the host computer and sends control signals to the drive circuit (2) through the I / O port. The drive circuit (2) controls the corresponding relay in the first relay group (3) to control the output capacitance value of the capacitor group (4). The drive circuit (2) selects the corresponding relay in the second relay group (5) and controls the drive circuit (2) to select the external coaxial contact of the corresponding product to provide output capacitance for the external product. The capacitor bank (4) includes capacitors with capacitance values ​​of C1, ..., ... i ..., C n n fixed-value capacitors, each capacitor is switched by two relays of the first relay group (3) to control the output capacitor between terminal 1 and common terminal, and the output capacitor between common terminal and terminal 2; The output capacitance ΔC of the capacitor bank (4) is the coefficient of each fixed-value capacitor. With capacitance C i The product, the capacity C i To balance ternary numbers The product of the difference in output capacitor value g and the required output capacitor value interval g. .

2. The programmable capacitor output device according to claim 1, characterized in that: ； Among them, C 奇 C is the capacitance value between terminal 1 and the common terminal of the capacitor bank (4). 偶 The capacitance value between terminals 2 and the common terminal of the capacitor bank (4); ； in, This represents the maximum value required for △C.

3. The programmable capacitor output device according to claim 1, characterized in that: g can be as small as 0.1 pF; When the value is -1, the relay connected to terminal 1 is disconnected, and the relay connected to terminal 2 is closed; When the value is 0, both the relay connected to terminal 1 and the relay connected to terminal 2 are disconnected; When the value is 1, the relay connected to terminal 1 is closed, and the relay connected to terminal 2 is open.

4. The programmable capacitor output device according to claim 1, characterized in that: The number of the communication and interface circuits (6) is at least two, and each of the communication and interface circuits (6) includes an output terminal 1, an output common terminal and an output terminal 2; The second relay group (5) includes m relay groups (51) connected in parallel. Each relay group (51) includes a 1-terminal relay (511), a common-terminal relay (512), and a 2-terminal relay (513) connected in parallel, and a capacitor C0 is connected between the 1-terminal relay (511) and the common-terminal relay (512), and between the common-terminal relay (512) and the 2-terminal relay (513), respectively. One end of the 1-terminal relay (511) is connected to one end of the capacitor group (4) and the other end is connected to the output terminal 1. One end of the common terminal relay (512) is connected to the common terminal of the capacitor group (4) and the other end is connected to the output terminal common terminal. One end of the 2-terminal relay (513) is connected to one end of the capacitor group (4) and the other end is connected to the output terminal 2. When there is no capacitor output, capacitor C0 can determine the state of the product under test.

5. A programmable capacitor output device according to claim 1, characterized in that: The processor circuit (1) includes a processor chip and peripheral clock, power conversion and programming interface circuits; the driving circuit (2) includes a multiplexing chip and a driving chip; The communication and interface circuit (6) includes an RS422 or RS485 serial communication interface circuit, an Ethernet interface circuit, and a coaxial connector. The relays in the first relay group (3) and the second relay group (5) are both reed relays; Each capacitor in the capacitor bank (4) has a different capacitance value, and the ratio of two adjacent capacitance values ​​is 3. The printed circuit boards of the processor circuit (1), the driver circuit (2), the first relay group (3), the capacitor group (4), the second relay group (5), and the coaxial connectors of the communication and interface circuit (6) are all shielded to ground.

6. A programmable capacitor output device according to claim 1, characterized in that: The number of capacitor groups (4) is at least two, providing capacitors with different capacitance ranges and capacitance difference intervals for the product under test; Each of the capacitor banks (4) is connected to a communication and interface circuit (6) via the second relay bank (5), and the communication and interface circuit (6) has at least one output.

7. A programmable capacitor output device according to any one of claims 1 to 6, characterized in that: The programmable capacitor output device is used in any of the following test scenarios: batch aging test, temperature cycling test, or vibration test of sensors based on the segmented capacitance measurement principle. Before testing, the number of capacitors n and the fixed capacitance value of each capacitor in the capacitor group (4) are obtained by using the required capacitance difference interval g and the required capacitance range. The capacitor group (4) is built and assembled to obtain the programmable capacitor output device. During testing, the product under test is connected to the communication and interface circuit (6), and the host computer software controls the opening and closing of the first relay group (3) to provide the required test capacitance for the product under test.

8. A programmable capacitor output device according to claim 7, characterized in that: When two or more products to be tested are subjected to batch aging test or temperature cycling test, all products to be tested are connected to the communication and interface circuit (6) and then placed in the batch aging test equipment or temperature cycling test equipment. When performance testing is required during the aging test or temperature cycling test, the host computer software controls the on / off state of the first relay group (3) and the second relay group (5) respectively to provide the required test capacitance for the products to be tested.

9. A programmable capacitor output device according to claim 8, characterized in that: When the specified capacitance difference intervals of multiple products under test are different or the capacitance ranges are incompatible, the programmable capacitor output device is equipped with at least two capacitor groups (4). All products under test are connected to the communication and interface circuit (6) and then placed into the batch aging test equipment or temperature cycling test equipment. When performance testing is required during aging test or temperature cycling test, the host computer software controls the on / off of the first relay group (3) and the second relay group (5) respectively to provide different specified capacitance difference intervals and capacitance ranges for the products under test.

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