Self-calibration circuit and method of dynamic blood glucose monitoring chip

Abstract

The invention provides a self-calibration circuit and method of a dynamic blood glucose monitoring chip. Relates to the field of dynamic blood glucose monitoring, and solves the problem that errors caused by input imbalance of operational amplifiers cannot be calibrated, in the circuit, a digital-to-analog converter transmits a first voltage value to a positive input end of a first operational amplifier and transmits a second voltage value to a positive input end of a second operational amplifier; the output end of the first operational amplifier is connected to a counter electrode of the sensor; the reference electrode of the sensor is connected with the negative input end of the first operational amplifier; the working electrode of the sensor is connected with the negative input end of the second operational amplifier; the output end of the second operational amplifier is transmitted to the first analog-to-digital converter and is connected to the second end of the first analog-to-digital converter through a jumper resistor. According to the invention, errors caused by input imbalance of the operational amplifier, errors caused by leakage current of all MOS (Metal Oxide Semiconductor) tubes on a signal link and calibration of a resistance value of the preposed operational amplifier circuit can be calibrated.

Description

Technical Field

[0001] The present invention relates to the technical field of dynamic blood glucose monitoring, and in particular to a self-calibration circuit and method for a dynamic blood glucose monitoring chip. Background Art

[0002] Diabetes is one of the chronic diseases with the largest patient base in the world. Continuous Glucose Monitoring (CGM) can reflect blood sugar changes throughout the day and effectively cover the detection blind spots. Effective blood sugar management can significantly improve the patient's prognosis and physical condition and reduce the incidence of complications. The preamplifier circuit used for CGM detection is a low-power circuit. Due to the mismatch of process and layout, the input offset of the op amp will cause a large deviation in the measured impedance value, and the offset between different chips will also be inconsistent, so each chip needs to be calibrated separately. In addition, since the measured current of the preamplifier circuit is too small, the MOS tube on the entire link will generate leakage current, which will cause test errors and need to be calibrated. Furthermore, since the Σ-ΔADC (Sigma-DeltaAnalog to Digital Converter, i.e., Σ-Δ analog-to-digital converter) is a differential input, there is an offset error and calibration is required.

[0003] Therefore, a method is urgently needed to calibrate the error caused by the input offset of the current pre-amplifier. Summary of the invention

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

[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 imbalance of the pre-operational amplifier circuit detected by CGM.

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

[0007] A continuous blood 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; set a first voltage value and a second voltage value through the digital-to-analog converter, connect the first voltage value output terminal to the positive input terminal of the first operational amplifier in the first operational amplifier adjustment circuit, and connect the second voltage value output terminal to the positive input terminal of the second operational amplifier in the second operational amplifier adjustment circuit; connect the output terminal of the first operational amplifier to the counter electrode of the continuous blood glucose sensor; connect the reference electrode of the continuous blood glucose sensor to the negative input terminal of the first operational amplifier, and connect the working electrode of the continuous blood glucose sensor to the negative input terminal of the second operational amplifier; connect the output terminal of the second operational amplifier to the test voltage input terminal of the first analog-to-digital converter, and connect the second voltage value output terminal to the second terminal of the first analog-to-digital converter through a jumper resistor; connect the output terminal of the first analog-to-digital converter to the input terminal of the microcontroller; connect the input terminal of the second analog-to-digital converter to the first voltage value output terminal, the second voltage value output terminal, the reference electrode, the working electrode, the second terminal of the second digital-to-analog converter, and the test voltage input terminal respectively.

[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, and the first offset calibration circuit includes a P-type field effect transistor array; the first resistor array and the first switch array form a series-parallel circuit, and the resistance in the circuit is changed by controlling the states of the switches in the first switch array. The voltage generated by the first DC power supply, the output voltage of the series-parallel circuit of the first resistor array and the first switch array, and the voltage generated by the first reference source are superimposed 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, and the second offset calibration circuit includes a P-type field effect transistor array; the second resistor array and the second switch array form a series-parallel circuit, and the resistance in the circuit is changed by controlling the states of the switches in the second switch array. The voltage generated by the second DC power supply, the output voltage of the series-parallel circuit of the second resistor array and the second switch array, and the voltage generated by the second reference source are superimposed 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, and the resistance calibration circuit includes: a constant temperature current source, a voltage source, a pad, 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 series-parallel circuit, and the number of N-type field effect transistors connected to the circuit is changed by controlling the states of the switches in the field effect transistor control switch array; the current mirror circuit and the current mirror control switch array form a series-parallel circuit, and the number of current mirrors connected to the circuit is changed by controlling the states of the switches in the current mirror control switch array; the resistor array and the resistor control switch array form a series-parallel circuit, and the resistors connected to the circuit are changed by controlling the states of the switches in the resistor control switch array; the constant temperature current source provides a constant temperature bias current to the series-parallel 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 series-parallel circuit of the N-type field effect transistor array and the field effect transistor control switch array are used to output a bias current through the series-parallel circuit of the current mirror circuit and the current mirror control switch array, and are transmitted to the series-parallel circuit of the resistor array and the resistor control switch array.

[0011] In a second aspect, the present invention further provides a self-calibration method for a continuous glucose monitoring chip, including:

[0012] Setting a first voltage value DAC01 and a second voltage value DAC02 through a digital-to-analog converter; applying the first voltage value DAC01 to the voltage value RE of the reference electrode of the continuous glucose sensor through a first operational amplifier adjustment circuit; applying the second voltage value DAC02 to the voltage value WE of the working electrode of the continuous glucose sensor through a second operational amplifier adjustment circuit; respectively detecting the voltage value RE of the reference electrode and the voltage value WE of the working electrode output by the continuous glucose sensor by using a second analog-to-digital converter; comparing the difference between the first voltage value DAC01 and the voltage value RE of the reference electrode, and comparing the difference between the second voltage value DAC02 and the voltage value WE of the working electrode; adjusting the resistance of the first operational amplifier adjustment circuit connected to the circuit according to the difference between the first voltage value DAC01 and the voltage value RE of the reference electrode, and adjusting the resistance of the second operational amplifier adjustment circuit connected to the 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 on the continuous glucose monitoring chip.

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

[0014] Set the first voltage value DAC01 and the second voltage value DAC02 to be equal through a digital-to-analog converter; use a second analog-to-digital converter to detect the output voltage values WE_OUT at the output terminals of the first voltage value DAC01 and the second operational amplifier in the second operational amplifier adjustment circuit respectively; determine the voltage error V1 generated by the leakage current according to the difference between the output voltage value WE_OUT and the first voltage value DAC01, and store it in the microcontroller.

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

[0016] Detect the output terminal voltage V2 of the first analog-to-digital converter, and determine the input offset of the first analog-to-digital converter according to the output terminal voltage V2 and the voltage error V1 generated by the leakage current.

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

[0018] Detect the operating environment temperature of the continuous glucose monitoring chip, and when the change in the operating environment temperature exceeds a preset temperature threshold, re-perform the self-calibration of the continuous glucose monitoring chip.

[0019] Preferably, the self-calibration method includes:

[0020] During wafer testing, a constant-temperature current source provides a constant-temperature bias current. Calibrate the constant-temperature bias current to the standard current Ia by configuring the states of each switch in the field-effect transistor control switch array Sa, and store the calibration configuration of the field-effect transistor control switch array Sa corresponding to the standard current Ia in a one-time programmable memory; when the continuous glucose sensor powers on and works each time, disconnect the first operational amplifier and the second operational amplifier, connect the resistance calibration circuit, and configure the mixed circuit of the current mirror circuit and the current mirror control switch array Sc to achieve the bias current Ic; transmit the bias current Ic to the mixed circuit of the resistance array and the resistance control switch array SR; use the first analog-to-digital converter to collect the output voltage value of the mixed circuit of the resistance array and the resistance control switch array; store the output voltage value in the microcontroller, and calculate the equivalent resistance of the mixed circuit of the resistance array and the resistance control switch array, and store it 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 on the continuous glucose monitoring chip includes:

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

[0023] The self - calibration circuit and method of the dynamic blood glucose monitoring chip in the embodiments of the present invention detect the errors brought by the circuit offset of the pre - operational amplifier of the CGM and the leakage current of the MOS transistors, and then calibrate the errors brought by the input offset of the operational amplifier, the errors brought by the leakage current of all MOS transistors on the signal chain, and the calibration of the resistance values of the pre - operational amplifier circuit, so as to improve the measurement accuracy and achieve the consistency of test results in batch production and at different temperatures.

[0024] These and other advantages of the present invention will become more obvious through the following detailed description of the best embodiments of the present invention in conjunction with the accompanying drawings. Description of the Drawings

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

[0026] Figure 1 is a schematic structural diagram of the self - calibration circuit of the dynamic blood glucose monitoring chip according to the embodiments of the present invention;

[0027] Figure 2 is a schematic diagram of the operational amplifier adjustment circuit according to the embodiments of the present invention;

[0028] Figure 3 is a schematic diagram of the resistance value calibration circuit according to the embodiments of the present invention;

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

[0030] Those skilled in the art should understand that the elements in the drawings are shown only for simplicity and clarity, and are not necessarily drawn to scale. For example, the sizes of some elements in the drawings may be enlarged relative to other elements to help improve the understanding of the embodiments of the present invention. Detailed Embodiments

[0031] The exemplary embodiments of the present invention will be described below in conjunction with the accompanying drawings. For the sake of clarity and conciseness, not all features of the actual embodiments are described in the specification. However, it should be understood that many implementation-specific decisions must be made during the development of any such actual embodiment in order to achieve the specific goals of the developer, for example, to comply with those constraints related to the system and the business, and such constraints may vary with different embodiments. In addition, it should also be understood that although the development work may be very complex and time-consuming, for those skilled in the art who benefit from the present disclosure, such development work is merely a routine task.

[0032] Here, it should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the device structures closely related to the solution according to the present invention are shown in the drawings, while other details less related to the present invention are omitted. As Figure 1 shown, the embodiments of the present invention provide a self-calibration circuit and method for a continuous glucose monitoring chip, which are used to calibrate the offset of the pre-operational amplifier circuit for CGM detection.

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

[0034] 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] Wherein, a first voltage value and a second voltage value are set through the digital-to-analog converter, 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 jumper resistor; the output terminal of the first analog-to-digital converter is connected to the input terminal of the microcontroller; the input terminals of the second analog-to-digital converter are respectively connected to the output terminal of the first voltage value, the output terminal of the second voltage value, the reference electrode, the working electrode, the second terminal of the second digital-to-analog converter, and the test voltage input terminal.

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

[0037] Figure 1 In the application of the CGM sensor chip, by setting the voltages 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, and by setting the first voltage value and the second voltage value of the digital-to-analog converter, the purpose of calibrating the circuit offset of the pre-amplification operation of the CGM and the error caused by the MOS transistor leakage current is achieved.

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

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

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

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

[0043] The counter electrode CE (Counter Electrode) of the continuous glucose sensor is connected to the output terminal of the above first operational amplifier adjustment circuit OPA1.

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

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

[0046] A first branch composed of a resistor array Rarray and a switch SW_TIA and a second branch composed of a second switch SW_CACB in parallel with the first branch are provided between the negative input terminal WE and the output terminal WE_OUT of the second operational amplifier adjustment circuit OPA2.

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

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

[0049] In the embodiment of the present 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 the embodiment of the present 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] As Figure 2 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 series-parallel circuit, and the resistance in the circuit is changed by controlling the states of the switches in the first switch array. The voltage generated by the first DC power supply, the output voltage of the series-parallel circuit of the first resistor array and the first switch array, and the voltage generated by the first reference source are superimposed 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 series-parallel circuit, and the resistance in the circuit is changed by controlling the states of the switches in the second switch array. The voltage generated by the second DC power supply, the output voltage of the series-parallel circuit of the second resistor array and the second switch array, and the voltage generated by the second reference source are superimposed 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 Among them, the structures of the first adjustment circuit and the second adjustment circuit are the same, 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. Among them, the above P-type field effect transistor array includes three P-type field effect transistors. The sources of two of the P-type field effect transistors are connected and connected to the drain of another P-type field effect transistor. The source of another P-type field effect transistor is connected to the DC power supply VCC, and the gate of another P-type field effect transistor is connected to the reference source VB.

[0054] The above resistor array and the above switch array SW form a series-parallel circuit, and the resistance in the circuit is changed by controlling the states of the switches in the first switch array. The resistor array includes X resistors, and the resistance values of each resistor 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. The 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 2Among them, taking X = 4 as an example, the resistor array includes 4 resistors, 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, and both 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 above DC power supply VCC is superimposed and transmitted to the P-type field effect transistor array through the output voltage of the series-parallel circuit of the resistor array and the switch array SW, as well as the voltage generated by the reference source VB; the above first operational amplifier includes a P-type field effect transistor array; among them, 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, the gate of the other P-type field effect transistor is connected to the reference source VB, and 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 the embodiment of the present invention, different Vb is selected through the switch array SW, the output voltage Va is output through the offset calibration circuit, the I1 and I2 of the operational amplifier OPA are compensated, and the output voltage values of the IP and IN ports are measured to make IP = IN close to or reach.

[0057] Such as Figure 3As shown, in the embodiment of the present invention, the second operational amplifier adjustment circuit further includes a resistance calibration circuit, and the resistance calibration circuit includes: a constant temperature current source, a voltage source, a pad, 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 series-parallel circuit, and the number of N-type field effect transistors connected to the circuit is changed by controlling the states of the switches in the field effect transistor control switch array; the current mirror circuit and the current mirror control switch array form a series-parallel circuit, and the number of current mirrors connected to the circuit is changed by controlling the states of the switches in the current mirror control switch array; the resistor array and the resistor control switch array form a series-parallel circuit, and the resistors connected to the circuit are changed by controlling the states of the switches in the resistor control switch array; the constant temperature current source provides a constant temperature bias current to the series-parallel 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 series-parallel circuit of the N-type field effect transistor array and the field effect transistor control switch array are used to realize the output of the bias current through the series-parallel circuit of the current mirror circuit and the current mirror control switch array, and are transmitted to the series-parallel 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 gates of each N-type field effect transistor. The sources of each N-type field effect transistor are 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 respectively generate a standard current Ia through one switch in the field effect transistor control switch array Sa, and the standard current Ia is transmitted to the current mirror circuit.

[0059] The above-mentioned current mirror circuit includes multiple P-type field effect transistors arranged in parallel. The sources of each P-type field effect transistor are connected to the voltage source VCC. The gates of each P-type field effect transistor are connected to the 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 the pad PAD. The drains of the remaining P-type field effect transistors respectively generate a bias current Ic through one switch in the current mirror control switch array Sc, and the bias current Ic is transmitted to the resistor array R array and the resistor control switch array SR.

[0060] The above-mentioned resistor array R array includes Y resistors. The resistance values of each resistor 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 control switch array SR, and the other ends of the Y-1 switches are grounded.

[0061] As Figure 4 shown, an embodiment of the present invention also provides a self-calibration method for a continuous glucose monitoring chip, including the following steps:

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

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

[0064] S130. Use a second analog-to-digital converter to respectively detect the voltage value RE of the reference electrode and the voltage value WE of the working electrode output by the continuous glucose sensor.

[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 resistance of the first operational amplifier adjustment circuit connected to the circuit according to the difference between the first voltage value DAC01 and the voltage value RE of the reference electrode, and adjust the resistance of the second operational amplifier adjustment circuit connected to the 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 on the continuous glucose monitoring chip.

[0067] In an embodiment of the present invention, in step S110, the first voltage value DAC01 and the second voltage value DAC02 can be set to be unequal respectively, for example, 0.7V and 0.5V respectively; then use the second analog-to-digital converter SARADC to respectively test the reference electrode RE and the working electrode WE, compare the difference between the first voltage value DAC01 and the reference electrode RE, adjust the first switch array SW1 and store it in the MCU register REG1, then compare the difference between the second voltage value DAC02 and the working electrode WE, and adjust the first switch array SW2 and store it in the MCU register REG2; until the error value between IP and IN reaches the minimum, approaching or reaching IP = IN.

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

[0069] Set the first voltage value DAC01 and the second voltage value DAC02 to be equal through a digital-to-analog converter;

[0070] Use a second analog-to-digital converter to detect the output voltage values WE_OUT at the output terminals of the first voltage value DAC01 and the second operational amplifier in the second operational amplifier adjustment circuit respectively.

[0071] Determine the voltage error V1 generated by the leakage current according to the difference between the output voltage value WE_OUT and the first voltage value DAC01, and store it in the microcontroller.

[0072] In the embodiment of the present 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, at this time, the second voltage value DAC02 and the output terminal WE_OUT should be equal; use the second analog-to-digital converter SARADC to test the voltage values of the first voltage value DAC01 and the output terminal WE_OUT respectively, and their difference is the error V1 generated by the leakage current, which is stored in the MCU for retrieval.

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

[0074] Detect the output terminal voltage V2 of the first analog-to-digital converter, and determine the input offset of the first analog-to-digital converter according to the output terminal voltage V2 and the voltage error V1 generated by the leakage current.

[0075] In the embodiment of the present invention, after the above situation is completed, use the first analog-to-digital converter Σ-ΔADC to test its output V2, and V2 - V1 is the input offset of the first analog-to-digital converter Σ-ΔADC.

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

[0077] Detect the operating environment temperature of the dynamic blood glucose monitoring chip, and when the change in the operating environment temperature exceeds a preset temperature threshold, re-perform the self-calibration of the dynamic blood glucose monitoring chip.

[0078] In the embodiment of the present invention, the above calibration needs to control the temperature change within a certain threshold range. For example, when the temperature change exceeds 5°C, it is necessary to re-calibrate according to the above process.

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

[0080] During wafer testing, a constant-temperature current source provides a constant-temperature bias current. By configuring the field-effect transistor control switch array Sa to control the states of each switch, the constant-temperature bias current is calibrated to the standard current Ia, and 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. When the continuous glucose sensor powers on and works each time, the first operational amplifier and the second operational amplifier are disconnected, and the resistance calibration circuit is connected. A mixed circuit of a current mirror circuit and a current mirror control switch array Sc is configured to implement the bias current Ic. The bias current Ic is transmitted to a mixed circuit of a resistor array and a resistor control switch array SR. The output voltage value of the mixed circuit of the resistor array and the resistor control switch array is collected by using a first analog-to-digital converter. The output voltage value is stored in a microcontroller, and the equivalent resistance of the mixed circuit of the resistor array and the resistor control switch array is calculated and stored in the microcontroller.

[0081] In an embodiment of the present invention, in the embodiment of the present invention, the copy current of the standard current Ia is tested through the pad PAD. Through the calibration of the field-effect transistor control switch array Sa, the current passing through the PAD is calibrated to the bias current Ic, and the corresponding calibrated configuration is recorded in the microcontroller MCU or EFUSE (one-time programmable memory). Then, each time the continuous glucose sensor powers on and works, the microcontroller MCU configures the current mirror control switch array Sc and the resistor control switch array SR according to requirements, and different bias currents Ic are configured through the current mirror circuit. The bias current Ic is connected to the resistor path by using the current mirror control switch array Sc. The first operational amplifier OPA1 and the second operational amplifier OPA2 are configured to be in an off state. At the same time, SW_RC1, SW_TIA, and SW_RC2 are turned on, and SW_CACB is turned off. At this time, the Figure 3 Ic in Figure 1 is connected to the Ic in Figure 3 so that the bias current Ic can flow into the resistor array R array and reach the ground. Figure 1 The resistor array R array in WE_OUT is WE_OUT an equivalent schematic diagram of the R array in

[0082] The voltage value of the resistor array R array is collected by using a second analog-to-digital converter SARADC. The collected voltage value is 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 the EFUSE here.

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

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

[0085] It should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application.

[0086] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, "a plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0087] In the present application, unless otherwise clearly specified and limited, terms such as "installed", "connected", "connected to", "fixed" and the like should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0088] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

[0089] Although the present invention has been described in terms of a limited number of embodiments, those skilled in the art, having the benefit of the foregoing description, will appreciate that other embodiments can be contemplated within the scope of the invention as thus described. In addition, it should be noted that the language used in this specification has been principally selected for readability and instructional purposes and not to limit or circumscribe the inventive subject matter. Accordingly, many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the appended claims. For the scope of the present invention, the disclosure herein is illustrative, and not restrictive, the scope of the invention being defined by the appended claims.

Claims

1. A self - calibration circuit for a dynamic blood glucose monitoring chip, characterized in that, Including: A continuous blood 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; Set a first voltage value and a second voltage value through the digital-to-analog converter, connect the first voltage value output terminal to the positive input terminal of the first operational amplifier in the first operational amplifier adjustment circuit, and connect the second voltage value output terminal 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 blood glucose sensor; the reference electrode of the continuous blood glucose sensor is connected to the negative input terminal of the first operational amplifier, and the working electrode of the continuous blood 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 second voltage value output terminal is connected to the second terminal of the first analog-to-digital converter through a jumper resistor; The output terminal of the first analog-to-digital converter is connected to the input terminal of the microcontroller; The input terminals of the second analog-to-digital converter are respectively connected to the first voltage value output terminal, the second voltage value output terminal, the reference electrode, the working electrode, the second terminal of the second digital-to-analog converter, and the test voltage input terminal.

2. The self-calibration circuit according to claim 1, wherein 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.

3. The self-calibration circuit according to claim 1 or 2, characterized in that, 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, and the first offset calibration circuit includes a P-type field effect transistor array; The first resistor array and the first switch array form a series-parallel circuit, and the resistance in the circuit is changed by controlling the states of the switches in the first switch array. The voltage generated by the first DC power supply, the output voltage of the series-parallel circuit of the first resistor array and the first switch array, and the voltage generated by the first reference source are superimposed 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, and the second offset calibration circuit includes a P-type field effect transistor array; The second resistor array and the second switch array form a series-parallel circuit, and the resistance in the circuit is changed by controlling the states of the switches in the second switch array. The voltage generated by the second DC power supply, the output voltage of the series-parallel circuit of the second resistor array and the second switch array, and the voltage generated by the second reference source are superimposed 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.

4. The self-calibration circuit according to claim 3, wherein The second operational amplifier adjustment circuit further includes a resistance calibration circuit, which includes: a constant temperature current source, a voltage source, a pad, 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 series-parallel circuit, and the number of N-type field effect transistors connected to the circuit is changed by controlling the states of the switches in the field effect transistor control switch array; the current mirror circuit and the current mirror control switch array form a series-parallel circuit, and the number of current mirrors connected to the circuit is changed by controlling the states of the switches in the current mirror control switch array; the resistor array and the resistor control switch array form a series-parallel circuit, and the resistors connected to the circuit are changed by controlling the states of the switches in the resistor control switch array; The constant temperature current source provides a constant temperature bias current to the series-parallel 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 series-parallel circuit of the N-type field effect transistor array and the field effect transistor control switch array are used to realize the output of the bias current through the series-parallel circuit of the current mirror circuit and the current mirror control switch array, and are transmitted to the series-parallel circuit of the resistor array and the resistor control switch array.

5. A self-calibration method for a dynamic blood glucose monitoring chip, characterized in that, Including: Setting a first voltage value DAC01 and a second voltage value DAC02 through a digital-to-analog converter; Applying the first voltage value DAC01 to the voltage value RE of the reference electrode of the continuous glucose sensor through a first operational amplifier adjustment circuit; Applying the second voltage value DAC02 to the voltage value WE of the working electrode of the continuous glucose sensor through a second operational amplifier adjustment circuit; Using a second analog-to-digital converter to respectively detect the voltage value RE of the reference electrode and the voltage value WE of the working electrode output by the continuous glucose sensor; Comparing the difference between the first voltage value DAC01 and the voltage value RE of the reference electrode, and comparing the difference between the second voltage value DAC02 and the voltage value WE of the working electrode; Adjusting the resistance of the first operational amplifier adjustment circuit connected to the circuit according to the difference between the first voltage value DAC01 and the voltage value RE of the reference electrode, and adjusting the resistance of the second operational amplifier adjustment circuit connected to the 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 on the dynamic blood glucose monitoring chip.

6. The self-calibration method according to claim 5, wherein, Further including: Setting the first voltage value DAC01 and the second voltage value DAC02 to be equal through a digital-to-analog converter; Using a second analog-to-digital converter to respectively detect the output voltage value WE_OUT at the output terminal of the first voltage value DAC01 and the second operational amplifier in the second operational amplifier adjustment circuit; Determining the voltage error V1 generated by the leakage current according to the difference between the output voltage value WE_OUT and the first voltage value DAC01, and storing it in the microcontroller.

7. The self-calibration method according to claim 6, wherein Further including: Detect the output voltage V2 of the first analog-to-digital converter, and determine the input offset of the first analog-to-digital converter according to the voltage error V1 generated by the output voltage V2 and the leakage current.

8. The self-calibration method according to any one of claims 5 to 7, characterized in that, It further includes: Detect the operating environment temperature of the continuous glucose monitoring chip, and when the change in the operating environment temperature exceeds a preset temperature threshold, re-perform the self-calibration of the continuous glucose monitoring chip.

9. The self-calibration method according to any one of claims 5 to 7, characterized in that It further includes: During wafer testing, the constant temperature current source provides a constant temperature bias current, and the states of the switches in the field-effect transistor control switch array Sa are controlled through configuration to calibrate the constant temperature bias current to the standard current Ia, and store the calibration configuration of the field-effect transistor control switch array Sa corresponding to the standard current Ia into the one-time programmable memory; When the continuous glucose sensor powers on and works each time, disconnect the first operational amplifier and the second operational amplifier, connect the resistance calibration circuit, and configure the mixed circuit of the current mirror circuit and the current mirror control switch array Sc to implement the bias current Ic; Transmit the bias current Ic to the mixed circuit of the resistor array and the resistor control switch array SR; Use the first analog-to-digital converter to collect the output voltage value of the mixed circuit of the resistor array and the resistor control switch array; Store the output voltage value into the microcontroller, calculate the equivalent resistance of the mixed circuit of the resistor array and the resistor control switch array, and store it into the microcontroller.

10. The self-calibration method according to claim 5, wherein Adjusting the resistance of the first operational amplifier adjustment circuit connected to the circuit according to the difference to perform self-calibration on the continuous glucose monitoring chip includes: Control the switch array in the first operational amplifier adjustment circuit to change the resistance connected to the circuit, so that the voltage value at the negative input terminal of the first operational amplifier in the first operational amplifier adjustment circuit is equal to the voltage value at the positive input terminal, or the difference between the voltage value at the negative input terminal and the voltage value at the positive input terminal meets a preset condition, and store the state of each switch in the switch array into the microcontroller.

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