High-precision two-dimensional resistor array reading circuit and measuring method

Abstract

The invention relates to a high-precision two-dimensional resistor array reading circuit and a measuring method. The circuit comprises a multi-path gating device, an M-row * N-column two-dimensional resistor array, an auxiliary measuring module and a data processing module, the auxiliary measurement module comprises N groups of auxiliary measurement units and a grounded voltage source, and each group of auxiliary measurement units comprises an operational amplifier and a reference resistor with known resistance; in each group of auxiliary measuring units, the in-phase input end of the operational amplifier is connected with a voltage source, the inverted input end of the operational amplifier is connected with a corresponding column line, and the output end of the operational amplifier is connected with the data processing module; when a certain row of resistance elements are measured, one end of the corresponding row line is directly grounded through the multi-path gating device, the other row lines are all suspended, and the data processing module calculates the resistance value of the resistance element on the corresponding column line according to the output of the operational amplifier of each group of auxiliary measuring units. Compared with the prior art, the measurement precision of the two-dimensional resistor array can be further improved on the basis that the circuit complexity is not improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic circuits, and particularly relates to a high-precision two-dimensional resistor array readout circuit and a measurement method. Background Art

[0002] With the improvement of technology and the replacement of materials, pressure sensors are gradually developing towards large-scale. Among them, piezoresistive sensors have been widely used in tactile sensing, pressure sensing, temperature sensing, etc. due to their high sensitivity and low cost. The resistor array is an important part of the piezoresistive sensor. In order to reduce the circuit complexity of the large-scale resistor array, it is usually connected into an M*N two-dimensional network. At this time, the entire resistor array only requires M+N leads. However, in this connection method, the current flowing through the non-measured resistors will affect the measurement accuracy of the measured resistors and increase the measurement error. In the prior art, the voltage feedback method (VFM) or the zero potential method (ZPM) is generally used to measure the resistance value of the resistor array. VFM reduces the potential difference across the non-measured resistors by feeding back the voltage at the output end to the other end of the non-measured resistors, thereby reducing the current on the non-measured resistors to reduce the error. ZPM uses an operational amplifier to achieve virtual common grounding at one end of the resistor unit. However, there are still certain measurement errors in the above two methods. Generally speaking, the error of the voltage feedback mode is higher. Therefore, based on the zero potential method, a dual-sampling detection circuit and a dynamic zero-current method have been derived. The dual-sampling detection circuit performs differential calculation after two samplings to reduce the influence brought by non-ideal interference, but the two sampling operations greatly reduce the measurement efficiency; the dynamic zero-current method detects the current of the non-measured resistors and uses feedback to reduce the current on the path of the non-measured resistors, thereby improving the measurement accuracy, but this increases the circuit complexity and greatly increases the hardware resource consumption and power consumption of the circuit. Another method is to construct a resistor or voltage matrix on the resistor array to solve the resistor array, but this method requires relatively complex data processing to obtain the resistor measurement value, and can only achieve global measurement and cannot select a specific area for measurement.

[0003] Chinese patent application with publication number CN109059969A proposes a resistive sensing array readout circuit and a measurement method. By using a first operational amplifier to enhance the driving ability of the multiplexer, the internal resistance of the row selector is removed from interfering with the measurement process; by using a second operational amplifier to form a negative feedback circuit, during measurement, the voltage across the non-measured resistive sensing unit is close to zero, which can effectively reduce the interference to the measurement process. However, in the above design, the offset voltage of the operational amplifier makes the potential difference across the non-measured resistors not zero. Therefore, it is necessary to redesign a two-dimensional resistor array readout circuit to further improve the measurement accuracy of the two-dimensional resistor array without increasing the circuit complexity. Summary of the Invention

[0004] The object of the present invention is to overcome the defects of the above-mentioned existing technologies and provide a high-precision two-dimensional resistor array reading circuit and a measurement method, which can further improve the measurement accuracy of the two-dimensional resistor array without increasing the circuit complexity.

[0005] The object of the present invention can be achieved by the following technical solutions:

[0006] The present invention provides a high-precision two-dimensional resistor array reading circuit, which includes a multiplexer, a two-dimensional resistor array, an auxiliary measurement module and a data processing module;

[0007] The two-dimensional resistor array includes M rows × N columns of resistor elements with unknown resistance values. One end of each row of resistor elements is connected to the same row line, and the other end is connected to different column lines; one end of each column of resistor elements is connected to the same column line, and the other end is connected to different row lines;

[0008] The auxiliary measurement module includes N groups of auxiliary measurement units and a grounded voltage source. Each column line of the two-dimensional resistor array corresponds to a group of auxiliary measurement units. Each group of auxiliary measurement units includes an operational amplifier and a reference resistor with a known resistance value; in each group of auxiliary measurement units, the non-inverting input terminal of the operational amplifier is connected to the voltage source, the inverting input terminal is connected to the corresponding column line, the output terminal is connected to the data processing module, one end of the reference resistor is connected to the inverting input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier;

[0009] One end of the multiplexer is grounded, and the other end is connected to all the row lines of the two-dimensional resistor array; when measuring the resistor elements in a certain row of the two-dimensional resistor array, one end of the corresponding row line is directly grounded through the multiplexer, and the other row lines are all floating. The data processing module calculates the resistance values of the resistor elements on the corresponding column lines according to the outputs of the operational amplifiers of each group of auxiliary measurement units.

[0010] Further, the reference resistor in the auxiliary measurement unit is an adjustable resistor.

[0011] Further, an analog-to-digital converter is provided between the data processing module and the operational amplifier.

[0012] Further, the multiplexer is controlled by a control logic.

[0013] Further, the data processing module calculates the resistance value of the resistor element through the following formula:

[0014]

[0015] where, R dut_ijis the resistance value of the resistor element at the i-th row and j-th column, RL j is the resistance value of the reference resistor of the auxiliary measurement unit corresponding to the j-th column line, V b is the output voltage of the voltage source, V out_j is the output voltage of the operational amplifier of the auxiliary measurement unit corresponding to the j-th column line.

[0016] The present invention also provides a high-precision two-dimensional resistor array measurement method using the high-precision two-dimensional resistor array readout circuit as described above, including the following steps:

[0017] One end of the row line corresponding to the resistor element to be measured in the two-dimensional resistor array is grounded through a multiplexer, and the remaining row lines are all suspended;

[0018] Turn on the grounded voltage source, read the output of the operational amplifier of each group of auxiliary measurement units, and calculate the resistance value of the resistor element on the corresponding column line.

[0019] Further, the reference resistor in the auxiliary measurement unit is an adjustable resistor.

[0020] Further, after performing analog-to-digital conversion on the output of the operational amplifier of each group of auxiliary measurement units, the resistance value calculation is performed.

[0021] Further, the multiplexer is controlled by control logic.

[0022] Further, the resistance value of the resistor element is calculated by the following formula:

[0023]

[0024] where R dut_ij is the resistor element at the i-th row and j-th column, RL j is the reference resistor of the auxiliary measurement unit corresponding to the j-th column line, V b is the voltage value output by the voltage source, V out_j is the output voltage of the operational amplifier of the auxiliary measurement unit corresponding to the j-th column line

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention provides a high-precision two-dimensional resistor array readout circuit, which includes a multiplexer, a two-dimensional resistor array, an auxiliary measurement module, and a data processing module. Among them, the two-dimensional resistor array includes M rows × N columns of resistor elements with unknown resistance values. One end of each row of resistor elements is connected to the same row line, and the other end is connected to different column lines. One end of each column of resistor elements is connected to the same column line, and the other end is connected to different row lines. The auxiliary measurement module includes N groups of auxiliary measurement units and a grounded voltage source. Each column line of the two-dimensional resistor array corresponds to a group of auxiliary measurement units. Each group of auxiliary measurement units includes an operational amplifier and a reference resistor with a known resistance value. In each group of auxiliary measurement units, the non-inverting input terminal of the operational amplifier is connected to the voltage source, the inverting input terminal is connected to the corresponding column line, and the output terminal is connected to the data processing module. One end of the reference resistor is connected to the inverting input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier. One end of the multiplexer is grounded, and the other end is connected to all the row lines of the two-dimensional resistor array. When measuring a certain row of resistor elements in the two-dimensional resistor array, one end of the corresponding row line is directly grounded through the multiplexer, rather than being connected to the power supply as in the prior art. There is no need to additionally set up a buffer operational amplifier. The operational amplifier in the auxiliary measurement unit undertakes both the functions of output voltage and driving circuit, which can further reduce the circuit complexity. One end of the resistor elements in the non-measured rows that are not connected to the operational amplifier is floating and not directly connected to any power supply excitation, which can reduce the interference amount of the potential at both ends of the resistor elements in the non-measured rows, thereby reducing the influence of the current on the non-measured resistor elements on the measurement result and further improving the measurement accuracy.

[0027] 2. In the present invention, the reference resistor in the auxiliary measurement unit is an adjustable resistor, which can be measured multiple times by changing the circuit wiring to ensure the accuracy of the measurement result. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of the high-precision two-dimensional resistor array readout circuit provided by the present invention;

[0029] Figure 2 is a schematic diagram of the circuit with the range feedback operational amplifier as the excitation buffer for input. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and gives the detailed implementation manner and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0031] Embodiment:

[0032] This embodiment provides a high-precision two-dimensional resistor array readout circuit, which includes a multiplexer, a two-dimensional resistor array, an auxiliary measurement module, and a data processing module.

[0033] Figure 1 It is a circuit diagram for measuring a 4×4 two-dimensional resistor array. The two-dimensional resistor array includes resistor elements R with unknown resistances arranged in 4 rows × 4 columns ij , where i = 1, 2, …, 4 and j = 1, 2, …, 4. One end of the resistor elements in each row is connected to the same row line, and the other end is connected to different column lines; one end of the resistor elements in each column is connected to the same column line, and the other end is connected to different row lines.

[0034] The auxiliary measurement module includes 4 groups of auxiliary measurement units and a grounded voltage source, and the output voltage of the voltage source is V b . Each column line of the two-dimensional resistor array corresponds to a group of auxiliary measurement units. Each group of auxiliary measurement units includes an operational amplifier and a reference resistor with a known resistance value (corresponding to Figure 1 R1, R2, R3, R4 in it). In each group of auxiliary measurement units, the non-inverting input terminal of the operational amplifier is connected to the voltage source, the inverting input terminal is connected to the corresponding column line, the output terminal is connected to the data processing module, one end of the reference resistor is connected to the inverting input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier. In a preferred embodiment, the reference resistor is an adjustable resistor.

[0035] One end of the multiplexer is grounded, and the other end is connected to all the row lines of the two-dimensional resistor array. When measuring the resistor elements in a certain row of the two-dimensional resistor array, one end of the corresponding row line of this row is directly grounded through the multiplexer instead of being connected to the power supply. If it is connected to the power supply, in order to ensure the power driving ability, a buffer unit (usually composed of an operational amplifier connected by unit negative feedback) needs to be connected after the power supply. Therefore, there is no need to add a buffer unit in the circuit designed in this embodiment, which can further reduce the complexity of the circuit; at the same time, since the voltage at the row end of the resistor array is directly provided by the ground and does not pass through the operational amplifier, the overall offset voltage in the circuit is reduced; in addition, the row lines of non-measured rows are all floating and not directly connected to any power supply excitation, which makes the non-measured rows in an open circuit state and no current passes through. In the prior art, the zero-current method reduces the current through feedback and cannot ensure complete elimination of the current. Therefore, the circuit designed in this embodiment can further improve the accuracy of the measurement result.

[0036] An analog-to-digital converter (ADC) is provided between the data processing module and the operational amplifier. The data processing module calculates the resistance values of the resistor elements on the corresponding column lines according to the outputs of the operational amplifiers of each group of auxiliary measurement units (corresponding to Figure 1 Vout1, Vout2, Vout3, Vout4 in it):

[0037]

[0038] Among them, R ij is the resistance value of the resistor element at the i-th row and j-th column, and R j is the resistance value of the reference resistor of the auxiliary measurement unit corresponding to the j-th column line, and V out_j is the output voltage of the operational amplifier of the auxiliary measurement unit corresponding to the j-th column line.

[0039] The steps of measuring using the above two-dimensional resistor array reading circuit are as follows:

[0040] S1. Through the control logic, control the multiplexer to ground one end of the row line corresponding to the resistor element of the row to be measured in the two-dimensional resistor array, and the remaining row lines are all floating;

[0041] S2. Turn on the grounded voltage source, read the output of the operational amplifier of each group of auxiliary measurement units, and calculate the resistance value of the resistor element on the corresponding column line.

[0042] The solution proposed in this embodiment simplifies the circuit and improves the measurement accuracy. The effectiveness of the high-precision two-dimensional resistor array reading circuit proposed in this embodiment can be verified through the following comparative calculations:

[0043] The error of a single resistor to be measured is: Among them, I er is the error current, and I test is the current of the resistor to be measured. It can be seen that the smaller the current on the non-resistor to be measured, the smaller the error caused. When the resistance is constant, that is, the smaller the potential difference across the non-resistor to be measured, the smaller the error caused. Assume that the offset voltages of the operational amplifiers used all follow a normal distribution, with a mean of μ and a standard deviation of σ. Then, it can be considered that the offset voltage of the operational amplifier in the worst case is (μ ± 3σ).

[0044] When using a range feedback operational amplifier as the excitation buffer for input, the connection of the non-resistor to be measured (Rudut) is as Figure 2 shown. It can be calculated that in an M*N array, the mean value of the currents on all non-resistors to be measured is E(I udut_all ) = 0, and the variance is In the worst case, the current on all resistors to be measured is I udut_all_max = 6σ·M·(N - 1).

[0045] In the circuit proposed in this embodiment, the mean value of the currents on all non-resistors to be measured is E(I udut_all ) = 0, and the variance is In the worst case, the current on all resistors to be measured is It can be seen from this that the circuit proposed in this embodiment optimizes the overall error of detection in the worst case.

[0046] Array piezoresistive sensors have a wide range of applications in many fields such as industrial automation and process control, medical devices, consumer electronics and smart homes, environmental monitoring and disaster warning. For example, in medical monitoring equipment, array piezoresistive sensors can be used to monitor physiological parameters such as a patient's blood pressure in real time; in a smart home system, array piezoresistive sensors can be used to monitor the pressure distribution on a mattress or seat cushion in real time to provide personalized health advice for users. The miniaturized and high-precision two-dimensional resistor array readout circuit designed in the present invention is applicable to systems with high requirements for measurement accuracy and stability, can fully improve the application performance of array piezoresistive sensors in various fields, and promote the continuous innovation and development of electronic circuit technology.

[0047] The above description of the embodiments is to enable those of ordinary skill in the art to understand and use the invention. Obviously, those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A high-precision two-dimensional resistor array readout circuit, characterized in that: It includes a multiplexer, a two-dimensional resistor array, an auxiliary measurement module and a data processing module; The two-dimensional resistor array includes M rows×N columns of resistor elements with unknown resistance values, one end of each row of resistor elements is connected to the same row line, and the other end is connected to different column lines; One end of each column of resistor elements is connected to the same column line, and the other end is connected to a different row line; The auxiliary measurement module includes N groups of auxiliary measurement units and a grounded voltage source, each column line of the two-dimensional resistor array corresponds to a group of auxiliary measurement units, and each group of auxiliary measurement units includes an operational amplifier and a reference resistor with a known resistance value; In each group of auxiliary measurement units, the operational amplifier has a non-inverting input terminal connected to the voltage source, an inverting input terminal connected to the corresponding column line, an output terminal connected to the data processing module, one end of the reference resistor is connected to the inverting input terminal of the operational amplifier, and the other end is connected to the output terminal of the operational amplifier; One end of the multiplexer is grounded, and the other end is connected to all the row lines of the two-dimensional resistor array; when measuring a row of resistor elements in the two-dimensional resistor array, one end of the row line corresponding to the row is directly grounded through the multiplexer, and the other row lines are left floating, and the data processing module calculates the resistance value of the resistor element on the corresponding column line according to the output of the operational amplifier of each group of auxiliary measurement units.

2. A high-precision two-dimensional resistor array readout circuit according to claim 1, characterized in that: The reference resistor in the auxiliary measurement unit is an adjustable resistor.

3. A high-precision two-dimensional resistor array readout circuit according to claim 1, characterized in that: An analog-to-digital converter is provided between the data processing module and the operational amplifier.

4. A high-precision two-dimensional resistor array readout circuit according to claim 1, characterized in that: The multiplexer is controlled by control logic.

5. The high-precision two-dimensional resistor array readout circuit according to claim 1, characterized in that: The data processing module calculates the resistance value of the resistor element by the following formula: Among them, R dut_ij is the resistance value of the resistor element in the i-th row and j-th column, RL j is the resistance value of the reference resistor of the auxiliary measurement unit corresponding to the jth column line, V b is the output voltage of the voltage source, V out_j is the output voltage of the operational amplifier of the auxiliary measurement unit corresponding to the j-th column line.

6. A high-precision two-dimensional resistor array measurement method using the high-precision two-dimensional resistor array readout circuit as claimed in claim 1, characterized in that: The following steps are involved: One end of the row line corresponding to the row resistor element to be tested in the two-dimensional resistor array is grounded through a multiplexer, and the other row lines are left hanging; The grounded voltage source is turned on, the output of the operational amplifier of each group of auxiliary measurement units is read, and the resistance value of the resistance element on the corresponding column line is calculated.

7. A high-precision two-dimensional resistor array measurement method according to claim 6, characterized in that: The reference resistor in the auxiliary measurement unit is an adjustable resistor.

8. A high-precision two-dimensional resistor array measurement method according to claim 6, characterized in that: After the output of the operational amplifier of each group of auxiliary measurement units is converted from analog to digital, the resistance value is calculated.

9. A high-precision two-dimensional resistor array measurement method according to claim 6, characterized in that: The multiplexer is controlled by control logic.

10. A high-precision two-dimensional resistor array measurement method according to claim 6, characterized in that: The resistance value of the resistor element is calculated using the following formula: Among them, R dut_ij is the resistance element in row i and column j, RL j is the reference resistance of the auxiliary measurement unit corresponding to the jth column line, V b is the voltage value output by the voltage source, V out_j is the output voltage of the operational amplifier of the auxiliary measurement unit corresponding to the j-th column line.

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