Self-calibration circuit and method for a continuous glucose monitoring chip

Abstract

The application provides a self-calibration circuit and method of a dynamic blood glucose monitoring chip. It relates to the field of dynamic blood glucose monitoring, and solves the problem of error caused by the input offset of the operational amplifier which cannot be calibrated. The circuit comprises a digital-to-analog converter which transmits a first voltage value to the positive input end of a first operational amplifier and transmits a second voltage value to the positive input end of a second operational amplifier; the output end of the first operational amplifier is connected to the counter electrode of a sensor; the reference electrode of the sensor is connected to the negative input end of the first operational amplifier, and the working electrode of the sensor is connected to the negative input end of the second operational amplifier; the output end of the second operational amplifier is transmitted to a first analog-to-digital converter, and the second end of the first analog-to-digital converter is accessed through a cross resistance. The application can calibrate the error caused by the input offset of the operational amplifier, the error caused by the drain current of all MOS tubes on the signal link, and the resistance value of the pre-operational amplifier circuit.

Description

Technical Field

[0001] This invention relates to the field of continuous glucose monitoring technology, and in particular to a self-calibration circuit and method for continuous glucose monitoring chips. Background Technology

[0002] Diabetes is one of the most prevalent chronic diseases globally, and continuous glucose monitoring (CGM) reflects blood glucose fluctuations throughout the day, effectively covering detection blind spots. Effective blood glucose management can significantly improve patient prognosis and physical condition, and reduce the incidence of complications. The preamplifier circuit used for CGM detection is a low-power circuit. Due to mismatches in manufacturing process and layout, input offset of the op-amp can lead to significant deviations in impedance measurements. Furthermore, the offset can vary between different chips, requiring individual calibration for each. Additionally, because the measured current of the preamplifier circuit is very small, leakage current occurs in the MOSFETs throughout the entire chain, introducing testing errors and necessitating calibration. Moreover, since the Σ-Δ ADC (Sigma-Delta Analog to Digital Converter) has differential inputs, it also exhibits offset errors and requires calibration.

[0003] Therefore, there is an urgent need for a method to calibrate the errors caused by the input misalignment of current preamplifiers. Summary of the Invention

[0004] A brief overview of the invention is given below to provide a basic understanding of certain aspects of it. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0005] In view of this, in order to solve the above problems, the present invention proposes a self-calibration circuit and method for a dynamic blood glucose monitoring chip to calibrate the misalignment of the preamplifier circuit for CGM detection.

[0006] This invention provides a self-calibration circuit for a dynamic blood glucose monitoring chip, comprising:

[0007] The system comprises a continuous glucose sensor, a first operational amplifier (op-amp) adjustment circuit, a second operational amplifier (op-amp) adjustment circuit, a first analog-to-digital converter (ADC), a second ADC, a digital-to-analog converter (DAC), and a microcontroller. The DAC sets a first voltage value and a second voltage value, and connects the output of the first voltage value to the positive input of the first operational amplifier in the first op-amp adjustment circuit, and connects the output of the second voltage value to the positive input of the second operational amplifier in the second op-amp adjustment circuit. The output of the first operational amplifier is connected to the counter electrode of the continuous glucose sensor. The reference electrode of the continuous glucose sensor is connected to the negative input of the first operational amplifier, and the working electrode of the continuous glucose sensor is connected to the negative input of the second operational amplifier. The output of the second operational amplifier is connected to the test voltage input of the first ADC, and the second voltage value output is connected to the second terminal of the first ADC via a bridging resistor. The output of the first ADC is connected to the input of the microcontroller. The input of the second ADC is connected to the first voltage value output, the second voltage value output, the reference electrode, the working electrode, the second terminal of the second ADC, and the test voltage input.

[0008] Preferably, the first analog-to-digital converter is a high-precision analog-to-digital converter, and the second analog-to-digital converter is a low-latency analog-to-digital converter.

[0009] Preferably, the first operational amplifier adjustment circuit includes a first operational amplifier and a first adjustment circuit; the first adjustment circuit includes a first DC power supply, a first reference source, a first resistor array, a first switch array, and a first offset calibration circuit, the first offset calibration circuit including a P-type field-effect transistor array; the first resistor array and the first switch array form a hybrid circuit, and the resistance in the circuit is changed by controlling the state of each switch in the first switch array; the voltage generated by the first DC power supply is superimposed on the output voltage of the hybrid circuit of the first resistor array and the first switch array and the voltage generated by the first reference source and transmitted to the first offset calibration circuit; the first operational amplifier includes a P-type field-effect transistor array; the output voltage of the first offset calibration circuit and the voltage generated by the first reference source are superimposed and transmitted to the first operational amplifier. The second operational amplifier adjustment circuit includes a second operational amplifier and a second adjustment circuit. The second adjustment circuit includes a second DC power supply, a second reference source, a second resistor array, a second switch array, and a second offset calibration circuit. The second offset calibration circuit includes a P-type field-effect transistor array. The second resistor array and the second switch array form a hybrid circuit, and the resistors in the circuit are changed by controlling the state of each switch in the second switch array. The voltage generated by the second DC power supply is superimposed on the output voltage of the hybrid circuit of the second resistor array and the second switch array and the voltage generated by the second reference source and transmitted to the second offset calibration circuit. The second operational amplifier includes a P-type field-effect transistor array. The output voltage of the second offset calibration circuit and the voltage generated by the second reference source are superimposed and transmitted to the second operational amplifier.

[0010] Preferably, the second operational amplifier adjustment circuit further includes a resistance calibration circuit, which includes: a constant temperature current source, a voltage source, pads, an N-type field-effect transistor array, a field-effect transistor control switch array, a current mirror circuit, a current mirror control switch array, a resistor array, and a resistor control switch array; the N-type field-effect transistor array and the field-effect transistor control switch array form a hybrid circuit, and the number of N-type field-effect transistors in the circuit is changed by controlling the state of each switch in the field-effect transistor control switch array; the current mirror circuit and the current mirror control switch array form a hybrid circuit, and the number of N-type field-effect transistors in the circuit is changed by controlling the state of each switch in the current mirror control switch array. The number of current mirrors in the access circuit is changed; the resistor array and the resistor control switch array form a hybrid circuit, and the resistance in the access circuit is changed by controlling the state of each switch in the resistor control switch array; the constant temperature current source provides a constant temperature bias current to the hybrid circuit of the N-type field-effect transistor array and the field-effect transistor control switch array; the voltage generated by the voltage source and the standard current generated by the hybrid circuit of the N-type field-effect transistor array and the field-effect transistor control switch array are used to realize the bias current output through the hybrid circuit of the current mirror circuit and the current mirror control switch array, and transmitted to the hybrid circuit of the resistor array and the resistor control switch array.

[0011] Secondly, the present invention also provides a self-calibration method for a dynamic blood glucose monitoring chip, comprising:

[0012] A first voltage value DAC01 and a second voltage value DAC02 are set using a digital-to-analog converter (DAC). The first voltage value DAC01 is applied to the voltage value RE of the reference electrode of the continuous glucose sensor through a first operational amplifier (op-amp) adjustment circuit. The second voltage value DAC02 is applied to the voltage value WE of the working electrode of the continuous glucose sensor through a second operational amplifier (op-amp) adjustment circuit. The voltage values ​​RE of the reference electrode and WE of the working electrode output by the continuous glucose sensor are detected using a second analog-to-digital converter (ADC). The difference between the first voltage value DAC01 and the voltage value RE of the reference electrode is compared, and the difference between the second voltage value DAC02 and the voltage value WE of the working electrode is compared. The resistor connected to the circuit of the first operational amplifier adjustment circuit is adjusted according to the difference between the first voltage value DAC01 and the voltage value RE of the reference electrode, and the resistor connected to the circuit of the second operational amplifier adjustment circuit is adjusted according to the difference between the second voltage value DAC02 and the voltage value WE of the working electrode, so as to perform self-calibration of the dynamic blood glucose monitoring chip.

[0013] Preferably, the self-calibration method further includes:

[0014] The first voltage value DAC01 and the second voltage value DAC02 are set to be equal by a digital-to-analog converter; the output voltage value WE_OUT of the second operational amplifier in the first voltage value DAC01 and the second operational amplifier adjustment circuit is detected by a second analog-to-digital converter; the voltage error V1 caused by leakage current is determined based on the difference between the output voltage value WE_OUT and the first voltage value DAC01, and stored in the microcontroller.

[0015] Preferably, the self-calibration method further includes:

[0016] The output voltage V2 of the first analog-to-digital converter is detected, and the input offset of the first analog-to-digital converter is determined based on the voltage error V1 caused by the leakage current between the output voltage V2 and the voltage error V1.

[0017] Preferably, the self-calibration method further includes:

[0018] The operating environment temperature of the dynamic blood glucose monitoring chip is detected. When the change in the operating environment temperature exceeds a preset temperature threshold, the dynamic blood glucose monitoring chip self-calibrates again.

[0019] Preferably, the self-calibration method is characterized by comprising:

[0020] During wafer testing, a constant-temperature current source provides a constant-temperature bias current. The constant-temperature bias current is calibrated to a standard current Ia by configuring the state of each switch in the MOSFET-controlled switch array Sa. The calibration configuration of the MOSFET-controlled switch array Sa corresponding to the standard current Ia is stored in a one-time programmable memory. Each time the continuous glucose sensor is powered on, the first and second operational amplifiers are disconnected, the resistance calibration circuit is connected, and a hybrid circuit of the current mirror circuit and the current mirror-controlled switch array Sc is configured to achieve a bias current Ic. The bias current Ic is transmitted to the hybrid circuit of the resistor array and the resistor-controlled switch array SR. The output voltage value of the hybrid circuit of the resistor array and the resistor-controlled switch array is acquired using a first analog-to-digital converter. The output voltage value is stored in the microcontroller, and the equivalent resistance of the hybrid circuit of the resistor array and the resistor-controlled switch array is calculated and stored in the microcontroller.

[0021] Preferably, adjusting the resistance of the first operational amplifier adjustment circuit connected to the circuit according to the difference to perform self-calibration of the dynamic blood glucose monitoring chip includes:

[0022] The switch array in the first operational amplifier adjustment circuit is controlled to change the resistance of the circuit so that the negative input voltage of the first operational amplifier in the first operational amplifier adjustment circuit is equal to the positive input voltage, or the difference between the negative input voltage and the positive input voltage meets a preset condition, and the state of each switch in the switch array is stored in the microcontroller.

[0023] The self-calibration circuit and method of the dynamic blood glucose monitoring chip in this embodiment of the invention improves measurement accuracy and achieves consistency of test results in batches and at different temperatures by detecting the circuit misalignment of the CGM preamplifier and the error caused by the leakage current of the MOS transistors, as well as the error caused by the leakage current of all MOS transistors in the signal link and the calibration of the resistance value of the preamplifier circuit.

[0024] These and other advantages of the invention will become more apparent from the following detailed description of the preferred embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0025] The present invention can be better understood by referring to the description given below in conjunction with the accompanying drawings, in which the same or similar reference numerals are used throughout the drawings to denote the same or similar parts. These drawings, together with the following detailed description, are incorporated in and form part of this specification, and are used to further illustrate preferred embodiments of the invention and explain the principles and advantages of the invention. In the drawings:

[0026] Figure 1 This is a schematic diagram illustrating the structure of the self-calibration circuit of the dynamic blood glucose monitoring chip according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram illustrating the operational amplifier adjustment circuit of an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram illustrating the resistance calibration circuit according to an embodiment of the present invention;

[0029] Figure 4 This is a flowchart illustrating the self-calibration method of the dynamic blood glucose monitoring chip according to an embodiment of the present invention.

[0030] Those skilled in the art will understand that the elements in the accompanying drawings are shown for simplicity and clarity only, and are not necessarily drawn to scale. For example, the dimensions of some elements in the drawings may be enlarged relative to other elements to aid in understanding the embodiments of the invention. Detailed Implementation

[0031] Exemplary embodiments of the invention will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of actual implementations are described in the specification. However, it should be understood that many implementation-specific decisions must be made in the development of any such actual embodiment to achieve the developer's specific goals, such as complying with constraints related to the system and business, and these constraints may vary depending on the implementation. Furthermore, it should be understood that while development work can be very complex and time-consuming, such development work is merely a routine task for those skilled in the art who benefit from this disclosure.

[0032] It should also be noted that, in order to avoid obscuring the invention with unnecessary details, only the device structure closely related to the solution according to the invention is shown in the accompanying drawings, while other details that are not closely related to the invention are omitted. Figure 1 As shown, embodiments of the present invention provide a self-calibration circuit and method for a dynamic blood glucose monitoring chip, used to calibrate the misalignment of the preamplifier circuit for CGM detection.

[0033] like Figure 1 As shown, the present invention provides a self-calibration circuit for a dynamic blood glucose monitoring chip, comprising:

[0034] The system comprises a continuous glucose sensor, a first operational amplifier adjustment circuit, a second operational amplifier adjustment circuit, a first analog-to-digital converter, a second analog-to-digital converter, a digital-to-analog converter, and a microcontroller.

[0035] Specifically, the digital-to-analog converter (DAC) sets a first voltage value and a second voltage value, and connects the output of the first voltage value to the positive input of the first operational amplifier in the first operational amplifier adjustment circuit, and connects the output of the second voltage value to the positive input of the second operational amplifier in the second operational amplifier adjustment circuit; the output of the first operational amplifier is connected to the counter electrode of the continuous glucose sensor; the reference electrode of the continuous glucose sensor is connected to the negative input of the first operational amplifier, and the working electrode of the continuous glucose sensor is connected to the negative input of the second operational amplifier; the output of the second operational amplifier is connected to the test voltage input of the first DAC, and the second voltage value output is connected to the second terminal of the first DAC through a bridging resistor; the output of the first DAC is connected to the input of the microcontroller; and the input of the second DAC is connected to the first voltage value output, the second voltage value output, the reference electrode, the working electrode, the second terminal of the second DAC, and the test voltage input.

[0036] Figure 1In the first operational amplifier adjustment circuit OPA1, the positive input terminal DAC01 and the negative input terminal RE (i.e., the reference electrode) are connected to the IP terminal and the IN terminal of the corresponding operational amplifier OPA, respectively. In the second operational amplifier adjustment circuit OPA2, the positive input terminal DAC02 and the negative input terminal WE (i.e., the working electrode) are connected to the IP terminal and the IN terminal of the corresponding operational amplifier OPA, respectively.

[0037] Figure 1 In the application of CGM sensor chips, by setting the voltage of the WE (Working Electrode) and RE (Reference Electrode) ports, the current generated by the continuous glucose sensor flows through the first operational amplifier adjustment circuit OPA1 and the second operational amplifier adjustment circuit OPA2. By setting the first and second voltage values ​​of the digital-to-analog converter, the purpose of calibrating the circuit misalignment of the CGM's preamplifier and the error caused by the leakage current of the MOS transistor can be achieved.

[0038] In the self-calibration circuit of the dynamic blood glucose monitoring chip in this embodiment of the invention, the digital-to-analog converter (DAC) outputs a first voltage value DAC01 and a second voltage value DAC02. The first voltage value DAC01 and the second voltage value DAC02 can be set to be equal or have a voltage difference.

[0039] The aforementioned first voltage value DAC01 is connected to the positive input terminal DAC01 of the aforementioned first operational amplifier adjustment circuit OPA1.

[0040] The aforementioned second voltage value DAC02 is connected to the positive input terminal DAC02 of the aforementioned second operational amplifier adjustment circuit OPA2.

[0041] The working electrode WE of the continuous glucose sensor is connected to the negative input terminal of the second operational amplifier adjustment circuit OPA2 mentioned above.

[0042] The reference electrode RE of the continuous glucose sensor is connected to the negative input terminal of the first operational amplifier adjustment circuit OPA1 mentioned above.

[0043] The counter electrode CE of the continuous glucose sensor is connected to the output of the first operational amplifier adjustment circuit OPA1.

[0044] According to the concept of virtual short, after the switch SW_RE is closed and turned on, the voltage of the reference electrode RE of the continuous glucose sensor is equal to the first voltage value DAC01.

[0045] The first operational amplifier adjustment circuit OPA1 outputs a voltage value CE_OUT. In a branch connected to this output, a series switch SW_RECE and a switch SW_REGND are connected. One end of switch SW_REGND is grounded. The CE signal of the continuous glucose sensor is connected to the output of the first operational amplifier adjustment circuit OPA1, and switch SW_CE is connected in series in this path.

[0046] The negative input terminal WE and the output terminal WE_OUT of the second operational amplifier adjustment circuit OPA2 mentioned above are provided with a first branch consisting of a resistor array Rarray and a switch SW_TIA, and a second branch consisting of a second switch SW_CACB connected in parallel with the first branch.

[0047] The resistance value of the above resistor R array is adjustable.

[0048] The test voltage output from the WE_OUT terminal of the second operational amplifier adjustment circuit OPA2 is fed into the test voltage input terminal of the first digital-to-analog converter (ADC), converted into a digital signal, and then fed into the microprocessor (MCU). The second voltage value DAC02 is connected to the second terminal of the first ADC via a bridging resistor.

[0049] In this embodiment of the invention, the first analog-to-digital converter is a high-precision analog-to-digital converter, and the second analog-to-digital converter is a low-latency analog-to-digital converter.

[0050] In this embodiment of the invention, the first analog-to-digital converter can be a Σ-ΔADC (Sigma-Delta Analog to Digital Converter), and the second analog-to-digital converter can be a SAR ADC (Successive Approximation Register Analog to Digital Converter).

[0051] like Figure 2 As shown in the embodiment of the present invention, the first operational amplifier adjustment circuit includes a first operational amplifier and a first adjustment circuit.

[0052] The first adjustment circuit includes a first DC power supply, a first reference source, a first resistor array, a first switch array, and a first offset calibration circuit. The first offset calibration circuit includes a P-type field-effect transistor array. The first resistor array and the first switch array form a hybrid circuit, and the resistance in the circuit is changed by controlling the state of each switch in the first switch array. The voltage generated by the first DC power supply is superimposed on the output voltage of the hybrid circuit of the first resistor array and the first switch array, and the voltage generated by the first reference source, and transmitted to the first offset calibration circuit. The first operational amplifier includes a P-type field-effect transistor array. The output voltage of the first offset calibration circuit and the voltage generated by the first reference source are superimposed and transmitted to the first operational amplifier. The second operational amplifier adjustment circuit includes a first... The system comprises a second operational amplifier and a second adjustment circuit. The second adjustment circuit includes a second DC power supply, a second reference source, a second resistor array, a second switch array, and a second offset calibration circuit. The second offset calibration circuit includes a P-type field-effect transistor array. The second resistor array and the second switch array form a hybrid circuit, and the resistors in the circuit are changed by controlling the state of each switch in the second switch array. The voltage generated by the second DC power supply is superimposed on the output voltage of the hybrid circuit of the second resistor array and the second switch array, and the voltage generated by the second reference source, and transmitted to the second offset calibration circuit. The second operational amplifier includes a P-type field-effect transistor array. The output voltage of the second offset calibration circuit and the voltage generated by the second reference source are superimposed and transmitted to the second operational amplifier.

[0053] Figure 2 In this circuit, the first adjustment circuit and the second adjustment circuit have the same structure, including a DC power supply VCC, a reference source VB, a resistor array, a switch array SW, and an offset calibration circuit. The offset calibration circuit includes a P-type field-effect transistor array. The P-type field-effect transistor array includes three P-type field-effect transistors, wherein the sources of two P-type field-effect transistors are connected and connected to the drain of another P-type field-effect transistor, the source of the other P-type field-effect transistor is connected to the DC power supply VCC, and the gate of the other P-type field-effect transistor is connected to the reference source VB.

[0054] The aforementioned resistor array and the aforementioned switch array SW form a hybrid circuit. The resistance in the circuit is changed by controlling the state of each switch in the first switch array. The resistor array includes X resistors, each with a resistance value that can be the same or different. The X resistors are connected end to end in sequence between the DC power supply VCC and the ground terminal. A switch is led out between every two adjacent resistors. X-1 switches form the switch array SW. The two ends of one of the switches are respectively connected to the gates of two P-type field-effect transistors in the P-type field-effect transistor array. Figure 2In the example of X=4, the resistor array includes 4 resistors and the switch array SW includes 3 switches. The 4 resistors are connected end to end in sequence between the DC power supply VCC and the ground terminal. A switch is led out between every two adjacent resistors. The two ends of the switch in the middle position are respectively connected to the gates of two P-type field-effect transistors in the P-type field-effect transistor array.

[0055] The voltage generated by the aforementioned DC power supply VCC is superimposed on the output voltage of the hybrid circuit of the resistor array and the switch array SW, and the voltage generated by the reference source VB, and transmitted to the P-type field-effect transistor array. The aforementioned first operational amplifier includes a P-type field-effect transistor array. The P-type field-effect transistor array of the first operational amplifier has the same structure as the P-type field-effect transistor array of the offset calibration circuit. The sources of two P-type field-effect transistors are connected and connected to the drain of another P-type field-effect transistor. The source of the other P-type field-effect transistor is connected to the DC power supply VCC, and the gate of the other P-type field-effect transistor is connected to the reference source VB. The drains of the two P-type field-effect transistors of the offset calibration circuit are respectively connected to the drains of the two P-type field-effect transistors of the first operational amplifier.

[0056] In this embodiment of the invention, different Vb values ​​are selected by the switch array SW, and the offset calibration circuit outputs voltage Va to compensate for I1 and I2 of the operational amplifier OPA. The output voltage values ​​of the IP and IN ports are measured to make IP close to or reach IN.

[0057] like Figure 3As shown in the embodiment of the present invention, the second operational amplifier adjustment circuit further includes a resistance calibration circuit. The resistance calibration circuit includes: a constant temperature current source, a voltage source, pads, an N-type field-effect transistor array, a field-effect transistor control switch array, a current mirror circuit, a current mirror control switch array, a resistor array, and a resistor control switch array. The N-type field-effect transistor array and the field-effect transistor control switch array form a hybrid circuit, and the number of N-type field-effect transistors in the circuit is changed by controlling the state of each switch in the field-effect transistor control switch array. The current mirror circuit and the current mirror control switch array form a hybrid circuit, and the number of N-type field-effect transistors in the circuit is changed by controlling the state of each switch in the current mirror control switch array. The state changes the number of current mirrors in the access circuit; the resistor array and the resistor control switch array form a hybrid circuit, and the resistance in the access circuit is changed by controlling the state of each switch in the resistor control switch array; the constant temperature current source provides a constant temperature bias current to the hybrid circuit of the N-type field-effect transistor array and the field-effect transistor control switch array; the voltage generated by the voltage source and the standard current generated by the hybrid circuit of the N-type field-effect transistor array and the field-effect transistor control switch array are used to realize the bias current output through the hybrid circuit of the current mirror circuit and the current mirror control switch array, and transmitted to the hybrid circuit of the resistor array and the resistor control switch array.

[0058] Figure 3 In the N-type field-effect transistor array, there are multiple N-type field-effect transistors arranged in parallel. One end of the constant temperature current source VBG is grounded, and the other end is connected to the gate of each N-type field-effect transistor. The source of each N-type field-effect transistor is grounded. The drain of the first N-type field-effect transistor is connected to the other end of the constant temperature current source VBG. The drains of the remaining N-type field-effect transistors generate a standard current Ia by controlling a switch in the switch array Sa. The standard current Ia is transmitted to the current mirror circuit.

[0059] The aforementioned current mirror circuit includes multiple P-type field-effect transistors arranged in parallel. The source of each P-type field-effect transistor is connected to a voltage source VCC, and the gate of each P-type field-effect transistor is connected to a standard current Ia. The drain of the first P-type field-effect transistor in the current mirror circuit is connected to the standard current Ia, the drain of the second P-type field-effect transistor is connected to a pad PAD, and the drains of the remaining P-type field-effect transistors generate bias current Ic through a switch in the current mirror control switch array Sc. The bias current Ic is transmitted to the resistor array R array and the resistor control switch array SR.

[0060] The aforementioned resistor array R array includes Y resistors, each with a resistance value that can be the same or different. The Y resistors are connected end to end in sequence between the bias current Ic and the ground terminal. A switch is led out between every two adjacent resistors. The Y-1 switches form a resistor-controlled switch array SR, and the other end of the Y-1 switches is grounded.

[0061] like Figure 4 As shown, this embodiment of the invention also provides a self-calibration method for a dynamic blood glucose monitoring chip, comprising the following steps:

[0062] S110, Set the first voltage value DAC01 and the second voltage value DAC02 through the digital-to-analog converter.

[0063] S120. The first voltage value DAC01 is applied to the continuous glucose sensor through the first operational amplifier adjustment circuit; the second voltage value DAC02 is applied to the voltage value WE of the working electrode of the continuous glucose sensor through the second operational amplifier adjustment circuit.

[0064] S130. The voltage values ​​RE of the reference electrode and WE of the working electrode output by the continuous glucose sensor are detected by the second analog-to-digital converter.

[0065] S140, compare the difference between the first voltage value DAC01 and the voltage value RE of the reference electrode, and compare the difference between the second voltage value DAC02 and the voltage value WE of the working electrode.

[0066] S150. Adjust the resistor connected to the circuit of the first operational amplifier adjustment circuit according to the difference between the first voltage value DAC01 and the voltage value RE of the reference electrode, and adjust the resistor connected to the circuit of the second operational amplifier adjustment circuit according to the difference between the second voltage value DAC02 and the voltage value WE of the working electrode, so as to perform self-calibration of the dynamic blood glucose monitoring chip.

[0067] In this embodiment of the invention, step S110 can be performed by setting the first voltage value DAC01 and the second voltage value DAC02 to be unequal, for example, 0.7V and 0.5V respectively; then, the second analog-to-digital converter SARADC is used to test the reference electrode RE and the working electrode WE respectively, and the difference between the first voltage value DAC01 and the reference electrode RE is compared. The first switch array SW1 is adjusted and stored in the MCU register REG1. Then, the difference between the second voltage value DAC02 and the working electrode WE is compared, and the first switch array SW2 is adjusted and stored in the MCU register REG2. This adjustment continues until the error value between IP and IN reaches its minimum, close to or reaching IP = IN.

[0068] In this embodiment of the invention, the self-calibration method further includes:

[0069] The first voltage value DAC01 and the second voltage value DAC02 are set to be equal by a digital-to-analog converter;

[0070] The output voltage value WE_OUT of the second operational amplifier in the second operational amplifier adjustment circuit is detected by the second analog-to-digital converter.

[0071] The voltage error V1 caused by the leakage current is determined based on the difference between the output voltage value WE_OUT and the first voltage value DAC01, and then stored in the microcontroller.

[0072] In this embodiment of the invention, the first voltage value DAC01 and the second voltage value DAC02 are set to be equal, for example, both are 0.7V. In theory, the second voltage value DAC02 and the output terminal WE_OUT should be equal. The second analog-to-digital converter SARADC is used to test the voltage values ​​of the first voltage value DAC01 and the output terminal WE_OUT respectively. The difference is the error V1 caused by leakage current, which is stored in the MCU for retrieval.

[0073] In this embodiment of the invention, the self-calibration method further includes:

[0074] The output voltage V2 of the first analog-to-digital converter is detected, and the input offset of the first analog-to-digital converter is determined based on the voltage error V1 caused by the leakage current between the output voltage V2 and the voltage error V1.

[0075] In this embodiment of the invention, after completing the above steps, the output V2 of the first analog-to-digital converter (Σ-ΔADC) is tested, where V2-V1 is the input offset of the first analog-to-digital converter (Σ-ΔADC).

[0076] In this embodiment of the invention, the self-calibration method further includes:

[0077] The operating environment temperature of the dynamic blood glucose monitoring chip is detected. When the change in the operating environment temperature exceeds a preset temperature threshold, the dynamic blood glucose monitoring chip self-calibrates again.

[0078] In this embodiment of the invention, the above calibration needs to control the temperature change to exceed a certain threshold range. For example, if the temperature change exceeds 5°C, it needs to be recalibrated according to the above procedure.

[0079] In this embodiment of the invention, the self-calibration method includes:

[0080] During wafer testing, a constant-temperature current source provides a constant-temperature bias current. The constant-temperature bias current is calibrated to a standard current Ia by configuring the state of each switch in the MOSFET-controlled switch array Sa. The calibration configuration of the MOSFET-controlled switch array Sa corresponding to the standard current Ia is stored in a one-time programmable memory. Each time the continuous glucose sensor is powered on, the first and second operational amplifiers are disconnected, the resistance calibration circuit is connected, and a hybrid circuit of the current mirror circuit and the current mirror-controlled switch array Sc is configured to achieve a bias current Ic. The bias current Ic is transmitted to the hybrid circuit of the resistor array and the resistor-controlled switch array SR. The output voltage value of the hybrid circuit of the resistor array and the resistor-controlled switch array is acquired using a first analog-to-digital converter. The output voltage value is stored in the microcontroller, and the equivalent resistance of the hybrid circuit of the resistor array and the resistor-controlled switch array is calculated and stored in the microcontroller.

[0081] In this embodiment of the invention, the current passing through the pad PAD is tested to replicate the standard current Ia. The current is calibrated to the bias current Ic by calibrating the field-effect transistor-controlled switch array Sa. The corresponding calibration configuration is recorded in the microcontroller MCU or EFUSE (one-time programmable memory). Then, each time the continuous glucose sensor powers on, the microcontroller MCU configures the current mirror-controlled switch array Sc and the resistor-controlled switch array SR according to requirements. Different bias currents Ic are configured through the current mirror circuit. The current mirror-controlled switch array Sc connects the bias current Ic to the resistor path, the first operational amplifier OPA1 and the second operational amplifier OPA2 are configured to be off, SW_RC1, SW_TIA, and SW_RC2 are turned on, and SW_CACB is turned off. At this time, Figure 3 IC access in Figure 1 The bias current Ic can flow into the resistor array R array and then to ground. Figure 3 The resistor array R array in the middle is Figure 1 Equivalent diagram of R array; obtain its corresponding voltage V through the output terminal WE_OUT of the second analog-to-digital converter SARADC. WE_OUT V WE_OUT The precise resistance value can be obtained by using / Ic and recorded in the MCU for easy retrieval in real time.

[0082] Then, the voltage values ​​of the resistor array R array are acquired using a second analog-to-digital converter (SARADC); the acquired voltage values ​​are stored in the microcontroller (MCU), and the corresponding resistance is calculated and stored in the microcontroller (MCU). At the same time, the deviation value from the designed resistance value can also be stored in EFUSE.

[0083] In this embodiment of the invention, adjusting the resistance of the first operational amplifier adjustment circuit connected to the circuit according to the difference to perform self-calibration of the dynamic blood glucose monitoring chip includes:

[0084] The switch array in the first operational amplifier adjustment circuit is controlled to change the resistance of the circuit so that the negative input voltage of the first operational amplifier in the first operational amplifier adjustment circuit is equal to the positive input voltage, or the difference between the negative input voltage and the positive input voltage meets a preset condition, and the state of each switch in the switch array is stored in the microcontroller.

[0085] It should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used 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. Therefore, they should not be construed as limitations on this application.

[0086] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0087] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0088] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

[0089] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and instructional purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

Claims

1. A self-calibration circuit for a dynamic blood glucose monitoring chip, characterized in that, include: A continuous glucose sensor, a first operational amplifier adjustment circuit, a second operational amplifier adjustment circuit, a first analog-to-digital converter, a second analog-to-digital converter, a digital-to-analog converter, and a microcontroller; The first voltage value and the second voltage value are set by the digital-to-analog converter, and the output terminal of the first voltage value is connected to the positive input terminal of the first operational amplifier in the first operational amplifier adjustment circuit, and the output terminal of the second voltage value is connected to the positive input terminal of the second operational amplifier in the second operational amplifier adjustment circuit. The output terminal of the first operational amplifier is connected to the counter electrode of the continuous glucose sensor; the reference electrode of the continuous glucose sensor is connected to the negative input terminal of the first operational amplifier, and the working electrode of the continuous glucose sensor is connected to the negative input terminal of the second operational amplifier. The output terminal of the second operational amplifier is connected to the test voltage input terminal of the first analog-to-digital converter, and the output terminal of the second voltage value is connected to the second terminal of the first analog-to-digital converter through a bridging resistor; The output of the first analog-to-digital converter is connected to the input of the microcontroller; The input terminals of the second analog-to-digital converter are respectively connected to the first voltage output terminal, the second voltage output terminal, the reference electrode, the working electrode, the second terminal of the second digital-to-analog converter, and the test voltage input terminal; The first analog-to-digital converter is a high-precision analog-to-digital converter, and the second analog-to-digital converter is a low-latency analog-to-digital converter; The first operational amplifier adjustment circuit includes a first operational amplifier and a first adjustment circuit; The first adjustment circuit includes a first DC power supply, a first reference source, a first resistor array, a first switch array, and a first offset calibration circuit, wherein the first offset calibration circuit includes a P-type field-effect transistor array; The first resistor array and the first switch array form a hybrid circuit, and the resistance in the circuit is changed by controlling the state of each switch in the first switch array. The voltage generated by the first DC power supply is transmitted to the first offset calibration circuit by superimposing the output voltage of the hybrid circuit of the first resistor array and the first switch array and the voltage generated by the first reference source. The first operational amplifier includes a P-type field-effect transistor array; The output voltage of the first offset calibration circuit and the voltage generated by the first reference source are superimposed and transmitted to the first operational amplifier; The second operational amplifier adjustment circuit includes a second operational amplifier and a second adjustment circuit; The second adjustment circuit includes a second DC power supply, a second reference source, a second resistor array, a second switch array, and a second offset calibration circuit, wherein the second offset calibration circuit includes a P-type field-effect transistor array; The second resistor array and the second switch array form a hybrid circuit, and the resistance in the circuit is changed by controlling the state of each switch in the second switch array. The voltage generated by the second DC power supply is transmitted to the second offset calibration circuit by superimposing the output voltage of the hybrid circuit of the second resistor array and the second switch array and the voltage generated by the second reference source. The second operational amplifier includes a P-type field-effect transistor array; The output voltage of the second offset calibration circuit and the voltage generated by the second reference source are superimposed and transmitted to the second operational amplifier.

2. The self-calibration circuit as described in claim 1, characterized in that, The second operational amplifier adjustment circuit also includes a resistance calibration circuit, which includes: a constant temperature current source, a voltage source, pads, an N-type field-effect transistor array, a field-effect transistor control switch array, a current mirror circuit, a current mirror control switch array, a resistor array, and a resistor control switch array; The N-type field-effect transistor array and the field-effect transistor control switch array form a hybrid circuit, and the number of N-type field-effect transistors in the circuit is changed by controlling the state of each switch in the field-effect transistor control switch array; the current mirror circuit and the current mirror control switch array form a hybrid circuit, and the number of current mirrors in the circuit is changed by controlling the state of each switch in the current mirror control switch array; the resistor array and the resistor control switch array form a hybrid circuit, and the resistance in the circuit is changed by controlling the state of each switch in the resistor control switch array. The constant-temperature current source provides a constant-temperature bias current to the hybrid circuit of the N-type field-effect transistor array and the field-effect transistor control switch array; the voltage generated by the voltage source and the standard current generated by the hybrid circuit of the N-type field-effect transistor array and the field-effect transistor control switch array are used to achieve bias current output through the hybrid circuit of the current mirror circuit and the current mirror control switch array, and are transmitted to the hybrid circuit of the resistor array and the resistor control switch array.

3. A self-calibration method for a dynamic blood glucose monitoring chip, characterized in that, include: The first voltage value DAC01 and the second voltage value DAC02 are set by a digital-to-analog converter; The first voltage value DAC01 is applied to the voltage value RE of the reference electrode of the continuous glucose sensor through the first operational amplifier adjustment circuit; The second voltage value DAC02 is applied to the voltage value WE of the working electrode of the continuous glucose sensor through the second operational amplifier adjustment circuit; The voltage values ​​RE of the reference electrode and WE of the working electrode output by the continuous glucose sensor are detected by the second analog-to-digital converter. Compare the difference between the first voltage value DAC01 and the voltage value RE of the reference electrode, and compare the difference between the second voltage value DAC02 and the voltage value WE of the working electrode; The resistor connected to the first operational amplifier adjustment circuit is adjusted according to the difference between the first voltage value DAC01 and the voltage value RE of the reference electrode, and the resistor connected to the second operational amplifier adjustment circuit is adjusted according to the difference between the second voltage value DAC02 and the voltage value WE of the working electrode, so as to perform self-calibration of the dynamic blood glucose monitoring chip.

4. The self-calibration method as described in claim 3, characterized in that, Also includes: The first voltage value DAC01 and the second voltage value DAC02 are set to be equal by a digital-to-analog converter; The output voltage value WE_OUT of the second operational amplifier in the second operational amplifier adjustment circuit is detected by the first voltage value DAC01 and the second operational amplifier adjustment circuit, respectively. The voltage error V1 caused by the leakage current is determined based on the difference between the output voltage value WE_OUT and the first voltage value DAC01, and then stored in the microcontroller.

5. The self-calibration method as described in claim 4, characterized in that, Also includes: The output voltage V2 of the first analog-to-digital converter is detected, and the input offset of the first analog-to-digital converter is determined based on the voltage error V1 caused by the leakage current between the output voltage V2 and the voltage error V1.

6. The self-calibration method as described in any one of claims 3 to 5, characterized in that, Also includes: The operating environment temperature of the dynamic blood glucose monitoring chip is detected. When the change in the operating environment temperature exceeds a preset temperature threshold, the dynamic blood glucose monitoring chip self-calibrates again.

7. The self-calibration method as described in any one of claims 3 to 5, characterized in that, Also includes: During wafer testing, a constant temperature current source provides a constant temperature bias current. The constant temperature bias current is calibrated to a standard current Ia by configuring the state of each switch in the field-effect transistor control switch array Sa. The calibration configuration of the field-effect transistor control switch array Sa corresponding to the standard current Ia is stored in a one-time programmable memory. Each time the continuous glucose sensor is powered on, the first and second operational amplifiers are disconnected, the resistance calibration circuit is connected, and a hybrid circuit of the current mirror circuit and the current mirror control switch array Sc is configured to realize the bias current Ic. The bias current Ic is transmitted to a hybrid circuit of resistor array and resistor-controlled switch array SR. The output voltage value of the hybrid circuit of resistor array and resistor-controlled switch array is acquired using the first analog-to-digital converter. The output voltage value is stored in the microcontroller, and the equivalent resistance of the hybrid circuit of the resistor array and the resistor-controlled switch array is calculated and stored in the microcontroller.

8. The self-calibration method as described in claim 3, characterized in that, Adjusting the resistor connected to the first operational amplifier adjustment circuit based on the difference to perform self-calibration of the dynamic blood glucose monitoring chip includes: The switch array in the first operational amplifier adjustment circuit is controlled to change the resistance of the circuit so that the negative input voltage of the first operational amplifier in the first operational amplifier adjustment circuit is equal to the positive input voltage, or the difference between the negative input voltage and the positive input voltage meets a preset condition, and the state of each switch in the switch array is stored in the microcontroller.

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