Conversion circuit, control method, chip and electronic device

Abstract

The present application provides a conversion circuit, a control method, a chip and an electronic device, which belongs to the field of electronic technology. The conversion circuit includes an ambient light reduction circuit, a correction current branch and a transimpedance amplification unit, wherein the ambient light reduction circuit and the correction current branch are respectively connected to the input end of the transimpedance amplification unit; the ambient light reduction circuit is configured to generate a reduction current based on the current ambient light current during the debugging stage; the correction current branch is configured to generate a correction current during the debugging stage, and the correction current is used to correct the reduction current. By adopting the present application, the mismatch effect of the ambient light reduction circuit can be reduced and the reduction effect of the ambient light current can be improved.

Description

Technical Field

[0001] The present application relates to the field of electronic technology, and in particular to a conversion circuit, a control method, a chip and an electronic device. Background Art

[0002] In bioelectric measurement, a current-type DAC (Digital-to-Analog Converter) inside the chip is usually used to reduce the ambient photocurrent to avoid TIA (Trans-Impedance Amplifier) ​​output saturation caused by the ambient photocurrent.

[0003] Since TIA is usually a differential op amp, the current-mode DAC needs to generate a source current and / or sink current that is equal in magnitude and opposite in direction to the ambient light current. Usually in a DAC, this current is generated by an equal number of PMOS and NMOS current source branches. Due to the mismatch of the PMOS and NMOS current sources in process manufacturing, there will be deviations in the source current and sink current. This current deviation needs to be corrected, otherwise it will cause the input voltage of the TIA to deviate from VDDA / 2 (VDDA is the TIA power supply voltage), further causing changes in the TIA gain and bandwidth, resulting in a decrease in the TIA conversion accuracy and an increase in the conversion time. Summary of the invention

[0004] In order to solve the problems of the prior art, the embodiments of the present application provide a conversion circuit, a control method, a chip and an electronic device, which can reduce the mismatch effect of the ambient light reduction circuit and improve the reduction effect of the ambient light current. The technical solution is as follows:

[0005] According to one aspect of the present application, a conversion circuit is provided, the conversion circuit comprising an ambient light reduction circuit, a correction current branch and a transimpedance amplification unit, the ambient light reduction circuit and the correction current branch being connected to an input end of the transimpedance amplification unit respectively;

[0006] The ambient light reduction circuit is configured to generate a reduction current based on a current ambient light current during a commissioning phase;

[0007] The correction current branch is configured to generate a correction current in the debugging phase, wherein the correction current is used to correct the clipping current.

[0008] According to another aspect of the present application, a control method of a conversion circuit is provided, wherein the conversion circuit comprises an ambient light reduction circuit, a correction current branch and a transimpedance amplification unit, wherein the ambient light reduction circuit and the correction current branch are respectively connected to an input end of the transimpedance amplification unit;

[0009] The method comprises:

[0010] In the debugging stage, the ambient light reduction circuit is controlled to generate a reduction current based on the current ambient light current;

[0011] In the debugging stage, the correction current branch is controlled to generate a correction current, and the correction current is used to correct the reduction current.

[0012] According to another aspect of the present application, a chip is provided, comprising the above-mentioned conversion circuit.

[0013] According to another aspect of the present application, an electronic device is provided, comprising the above-mentioned conversion circuit.

[0014] In the present application, the conversion circuit includes an ambient light reduction circuit and a correction current branch. While reducing the ambient light current through the ambient light reduction circuit, the mismatch effect of the ambient light reduction circuit can be further reduced through the correction current branch, thereby improving the reduction effect of the ambient light current. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Further details, features and advantages of the present application are disclosed in the following description of exemplary embodiments in conjunction with the accompanying drawings, in which:

[0016] Figure 1 A schematic diagram of a conversion circuit provided according to an exemplary embodiment of the present application is shown;

[0017] Figure 2 A schematic diagram of a conversion circuit of a differential structure provided according to an exemplary embodiment of the present application is shown;

[0018] Figure 3 A schematic diagram of a conversion circuit provided according to an exemplary embodiment of the present application is shown;

[0019] Figure 4 A schematic diagram of a Flash ADC circuit provided according to an exemplary embodiment of the present application is shown;

[0020] Figure 5 A schematic diagram of an ambient light reduction conversion cycle provided according to an exemplary embodiment of the present application is shown;

[0021] Figure 6 A schematic diagram of a Flash ADC circuit provided according to an exemplary embodiment of the present application is shown;

[0022] Figure 7 A schematic diagram of a correction current conversion cycle provided according to an exemplary embodiment of the present application is shown;

[0023] Figure 8 A schematic diagram of a correction current conversion cycle provided according to an exemplary embodiment of the present application is shown;

[0024] Fig. 9A schematic diagram of a correction current conversion cycle provided according to an exemplary embodiment of the present application is shown;

[0025] Fig.10 A schematic diagram of a correction current conversion cycle provided according to an exemplary embodiment of the present application is shown;

[0026] Fig.11 A schematic diagram of a correction current conversion cycle provided according to an exemplary embodiment of the present application is shown;

[0027] Fig.12 A schematic diagram of correcting current branch control provided according to an exemplary embodiment of the present application is shown;

[0028] Fig.13 A flow chart of a control method for a conversion circuit provided according to an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0029] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0030] In order to enable those skilled in the art to better understand the solutions of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0031] In the embodiments of the present application, at least one refers to one or more; multiple refers to two or more. In the description of the present application, the words "first", "second", "third", etc. are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying an order.

[0032] References to "one embodiment" or "some embodiments" etc. described in this specification mean that one or more embodiments of the present application include a particular feature, structure or characteristic described in conjunction with the embodiment. Thus, in this specification, the terms "include", "comprises", "has" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.

[0033] It should be noted that in the embodiments of the present application, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent three situations: A exists alone, A and B exist at the same time, and B exists alone.

[0034] It should be noted that in the embodiments of the present application, "connection" can be understood as electrical connection, and the connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be either a direct connection between A and B or an indirect connection between A and B through one or more other electrical components.

[0035] An embodiment of the present application provides a conversion circuit, which can be integrated in a chip or set in an electronic device.

[0036] In a possible application example, the conversion circuit can be applied to a bioelectric measurement device, which can also be provided with a light-emitting device and a light detection device. As an example, the above-mentioned bioelectric measurement device can be a bracelet, the light-emitting device can include an LED (Light-Emitting Diode), and the light detection device can include a photoelectric sensor. When the bracelet is used, the LED can be controlled to emit light to illuminate the user's skin, and the photoelectric sensor detects the light reflected by the user's skin to generate a photocurrent. By processing the photocurrent, the user's heart rate, blood parameters, etc. are obtained.

[0037] The operation of the bioelectric measurement device can be divided into two stages, the first stage can be referred to as the debugging stage, and the second stage can be referred to as the measurement stage. In the debugging stage, the light-emitting device may not emit light, and the bioelectric measurement device may be debugged based on the ambient light. At this time, the light detection device may generate a photocurrent of the ambient light; in the measurement stage, the light-emitting device may emit light, and the bioelectric measurement device may measure based on the currently detected light. At this time, in some application scenarios, the light detection device may generate a photocurrent under the combined influence of the ambient light and the light reflected by the user's skin.

[0038] The photocurrent processed in the measurement phase may be affected by ambient light, so debugging can be performed based on ambient light in the debugging phase to eliminate the influence of ambient light. The above debugging phase and measurement phase can be implemented alternately to adapt to changes in ambient light. This embodiment does not limit the timing relationship between the debugging phase and the measurement phase.

[0039] The conversion circuit provided in this embodiment can receive the photocurrent output by the light detection device and convert the photocurrent into a corresponding voltage for subsequent circuit processing. This embodiment will introduce the relevant configuration of the conversion circuit in the debugging phase, and will not introduce the measurement phase in detail.

[0040] Reference Figure 1The schematic diagram of the conversion circuit shown in the figure can include an ambient light reduction circuit, a correction current branch and a transimpedance amplifier unit. The input end of the transimpedance amplifier unit can be connected to the input end of the conversion circuit, the ambient light reduction circuit, and the correction current branch, and the output end can be connected to the output end of the conversion circuit (or serve as the output end of the conversion circuit). The transimpedance amplifier unit usually includes a TIA, so this embodiment will be introduced based on a differential structure.

[0041] in:

[0042] The ambient light mitigation circuit may be configured to generate a mitigation current based on a current ambient light current during a commissioning phase;

[0043] The correction current branch may be configured to generate a correction current during the debugging phase, and the correction current may be used to correct the above-mentioned reduction current.

[0044] Optionally, the above-mentioned current reduction may include a pull current and a sink current, and the correction current may also include a pull current and a sink current. The pull current may refer to a current drawn from the input end of the transimpedance amplifier unit to reduce the input current of the input end of the transimpedance amplifier unit; the sink current may refer to a current injected into the input end of the transimpedance amplifier unit to increase the input current of the input end of the transimpedance amplifier unit. As an example, refer to Figure 2 In the schematic diagram of the conversion circuit of the differential structure shown, the first input end (such as the non-inverting input end) of the transimpedance amplification unit can be used to receive the source current of the ambient light reduction circuit and the correction current branch, and the second input end (such as the inverting input end) can be used to receive the injection current of the ambient light reduction circuit and the correction current branch. Of course, the first input end can also be used to receive the injection current and the second input end can be used to receive the source current, or the first input end can be used to receive the source current of the ambient light reduction circuit and the injection current of the correction current branch, and the second input end can be used to receive the injection current of the ambient light reduction circuit and the source current of the correction current branch. This embodiment does not limit the configuration relationship between the source and the injection current and the input end of the transimpedance amplification unit.

[0045] In a possible implementation, during the debugging phase, the light detection device can detect ambient light and generate ambient light current. The conversion circuit can receive the ambient light current and control the ambient light reduction circuit to generate a corresponding reduction current to reduce the ambient light current.

[0046] When there is no photocurrent, the input voltage of the transimpedance amplifier unit is a preset voltage. Exemplarily, the preset voltage may be half of the power supply voltage, that is, VDDA / 2, where VDDA is the power supply voltage. Since the ambient light reduction circuit may have a mismatch in process manufacturing, the reduction current may not be able to completely reduce the ambient light current, so that the input voltage of the transimpedance amplifier unit deviates from the above-mentioned preset voltage. The conversion circuit can refer to the above-mentioned reduction current and control the correction current branch to generate a corresponding correction current, so as to reduce the distance between the input voltage of the transimpedance amplifier unit and the above-mentioned preset voltage, that is, to achieve the correction of the above-mentioned reduction current.

[0047] Through the above configuration, under the current ambient light, the input end of the transimpedance amplifier unit can receive the voltage of the above preset voltage or a voltage close to the above preset voltage, and the preset voltage is the input voltage of the transimpedance amplifier unit when there is a set no-light current, which eliminates the influence of the current ambient light and reduces the ambient light current.

[0048] Furthermore, the mismatch effect of the ambient light reduction circuit is further reduced by correcting the current branch, thereby improving the reduction effect on the ambient light current.

[0049] Optional, see Figure 3 The conversion circuit schematic diagram shown in FIG. 1 may further include a Flash ADC circuit. The ambient light reduction circuit and the correction current branch may be controlled by a binary code value, and the binary code value may be generated by the Flash ADC circuit. The Flash ADC circuit may generate a binary code value by using existing principles, which will not be described in detail in this embodiment.

[0050] The Flash ADC circuit may include multiple conversion cycles, wherein the ambient light reduction control code value of the ambient light reduction circuit and the correction control code value of the correction current branch may be generated in different conversion cycles. It is worth noting that the ambient light reduction control code value of the ambient light reduction circuit and the correction control code value of the correction circuit branch may be generated by two different Flash ADC circuits, or the ambient light reduction control code value of the ambient light reduction circuit and the correction control code value of the correction current branch may be generated by one Flash ADC circuit.

[0051] Accordingly, the Flash ADC circuit may be configured to generate an ambient light reduction control code value based on the output voltage of the transresistance amplifier unit during a conversion period corresponding to the ambient light reduction circuit, so as to control the ambient light reduction circuit.

[0052] In a possible implementation, in a conversion cycle corresponding to the ambient light reduction circuit, the input end of the Flash ADC circuit can be used to receive the output voltage of the transimpedance amplifier unit. Figure 4In the schematic diagram of the Flash ADC circuit shown, the first input terminal of the Flash ADC circuit can be used to receive the output voltage OUTP of the first output terminal of the transresistance amplifier unit, and the second input terminal can be used to receive the output voltage OUTN of the second output terminal of the transresistance amplifier unit.

[0053] The principle of ambient light reduction is introduced below.

[0054] Reference Figure 4 , considering the ambient light reduction circuit current mismatch and R F In the case of resistor mismatch, the following expression can be obtained:

[0055] OUTP=VCMP+(I AMB -I ofp )*(R F +ΔR F ) (1)

[0056] OUTN=VCMN-(I AMB -I ofn )*R F (2)

[0057] By reorganizing formula (1) and (2), we can get the following formula (3):

[0058] OUTP-OUTN=(2*I AMB -I ofp -I ofn )*R F +V os,TIA -I ofp *ΔR F (3)

[0059] Among them, OUTP is the positive output voltage of the transresistance amplifier unit, OUTN is the negative output voltage of the transresistance amplifier unit, VCMP is the positive input voltage of the transresistance amplifier unit, VCMN is the negative input voltage of the transresistance amplifier unit, I ofp is the sum of the current drawn by the ambient light reduction circuit and the correction current branch, I ofn It is the sum of the currents of the ambient light reduction circuit and the correction current branch. F is the transimpedance of the transimpedance amplifier unit, ΔR F For the two transresistors R F Deviation, ΔR F It is caused by the mismatch in process manufacturing, usually R F 0.1% of V os,TIA is the output offset of the TIA, which refers to the output voltage of the TIA when there is no input current.

[0060] When there is ambient light current, OUTP-OUTN is not equal to 0. The purpose of reducing the ambient light current is to make OUTP-OUTN approach 0. Therefore, the Flash ADC circuit can generate a corresponding ambient light reduction control code value by quantizing OUTP-OUTN.

[0061] Furthermore, the ambient light reduction circuit can be controlled by the ambient light reduction control code value, so that the ambient light reduction circuit can convert the received ambient light reduction control code value into a source current and a sink current, so that OUTP-OUTN approaches zero.

[0062] Optionally, the conversion cycle corresponding to the ambient light reduction circuit may include multiple conversion cycles. As an example, the number of bits of the Flash ADC circuit may be 4 bits, and the number of bits of the ambient light reduction circuit may be 12 bits. The number of conversion cycles corresponding to the ambient light reduction circuit may be 4, and in each conversion cycle, the Flash ADC circuit may determine a 4-bit ambient light reduction control code value. Due to the quantization error of the Flash ADC circuit, the number of bits of each conversion may overlap to a certain extent to avoid the high-bit conversion error affecting the low-bit conversion result. For example, the ambient light reduction control code values ​​of the 4 conversions may correspond to the number of bits of the ambient light reduction circuit of 12 bits to 9 bits, 9 bits to 6 bits, 6 bits to 3 bits, and 3 bits to 1 bit.

[0063] Optionally, in each conversion cycle corresponding to the ambient light reduction circuit, the transresistance value used by the transresistance amplifier unit is different, and the transresistance value increases in the order of the conversion cycles. Taking a 4-bit Flash ADC circuit as an example, in each conversion cycle, the upper and lower limits of the Flash ADC circuit voltage can be ±VREF, and the unit current Istep used for the quantized current is 2*VREF / (2*R F *2 4 )=VREF / (16*R F ). Transresistance R F As the selection of increases, the quantization accuracy of each conversion cycle gradually increases, making the reduction current gradually approach the ambient photocurrent. Figure 5 The schematic diagram of the ambient light reduction conversion cycle is shown in Figure 1. The transresistance values ​​used in each conversion cycle are 2K, 10K, 50K, and 250K, respectively. Of course, R F The increase ratio of can be selected according to the number of bits of the Flash ADC circuit. This embodiment does not limit the specific selected transresistance value.

[0064] The implementation principle of the correction current branch will be introduced below.

[0065] This embodiment provides two feasible ways to determine the binary code value (ie, the correction control code value) of the correction current branch.

[0066] In the first approach, a correction control code value is generated by a Flash ADC circuit. In this embodiment, the correction control code value is referred to as a first correction control code value.

[0067] Accordingly, the Flash ADC circuit may be configured to generate a first correction control code value based on the input voltage of the transresistance amplifier unit and a preset voltage during a conversion period corresponding to the correction current branch, so as to control the correction current branch.

[0068] In a possible implementation, in the conversion cycle corresponding to the correction current branch, the input end of the Flash ADC circuit can be used to receive the input voltage of the transimpedance amplifier unit and the preset voltage. Optionally, the input voltage can refer to the common mode input voltage. Figure 6 The schematic diagram of the Flash ADC circuit shown in FIG. 1 shows a first input terminal of the Flash ADC circuit that can be used to receive the common-mode input voltage VCM of the transimpedance amplifier unit. IN , the second input terminal can be used to receive a preset voltage VDDA / 2.

[0069] Optional, such as Figure 4 As shown, in the conversion cycle corresponding to the ambient light reduction circuit, the first input terminal of the Flash ADC circuit can be used to receive the output voltage of the first output terminal of the transresistance amplifier unit, and the second input terminal can be used to receive the output voltage of the second output terminal of the transresistance amplifier unit.

[0070] like Figure 6 As shown, in the conversion period corresponding to the correction current branch, the first input terminal of the Flash ADC circuit is used to receive the input voltage of the transresistance amplifier unit, and the second input terminal is used to receive the preset voltage, that is, VDDA / 2.

[0071] In a possible implementation, the input signal of the Flash ADC circuit can be switched by a switch unit. When switching from a conversion period corresponding to the correction current branch to a conversion period corresponding to the ambient light reduction circuit, the switch unit can be configured to connect the output voltage of the first output terminal of the transimpedance amplifier unit to the first input terminal of the Flash ADC circuit, and connect the output voltage of the second output terminal of the transimpedance amplifier unit to the second input terminal of the Flash ADC circuit; when switching from a conversion period corresponding to the ambient light reduction circuit to a conversion period corresponding to the correction current branch, the switch unit can be configured to connect the input voltage of the transimpedance amplifier unit to the first input terminal of the Flash ADC circuit, and connect the preset voltage to the second input terminal of the Flash ADC circuit.

[0072] The principle of correcting the mismatch of the ambient light reduction circuit will be introduced below.

[0073] Reference Figure 6 , considering the current mismatch of the ambient light reduction circuit and the RF resistance mismatch, the above expressions (1) and (2) can also be obtained. By reorganizing the above expressions (1) and (2), the following expression (4) can be obtained:

[0074] VCM IN -VCM OUT =(VCMP+VCMN) / 2-(OUTP+OUTN) / 2

[0075] =(I ofp -I ofn )*R F / 2-(I AMB -I ofn )*ΔR F / twenty four)

[0076] Among them, VCM IN -VCM OUT is the common mode deviation of the transimpedance amplifier unit.

[0077] The common mode deviation of the transimpedance amplifier unit is mainly caused by the mismatch of the ambient light reduction circuit. When there is a mismatch, VCM IN -VCM OUT Not equal to 0, the purpose of mismatch correction is to make VCM IN -VCM OUT approaches 0, so the Flash ADC circuit can IN -VCM OUT Quantization is performed to generate a corresponding first correction control code value.

[0078] Furthermore, the correction current branch can be controlled by the first correction control code value, so that the correction current branch can convert the received first correction control code value into a source current and a sink current, so that VCM IN -VCM OUT Approaching 0. That is, the common-mode deviation of the transimpedance amplifier unit is reduced, thereby improving the bandwidth and gain stability of the transimpedance amplifier unit, improving the conversion accuracy of the transimpedance amplifier unit, and reducing the conversion time of the transimpedance amplifier unit.

[0079] It should be noted that the above VCM OUT can be configured as VDDA / 2 (i.e. the above preset voltage), that is, VCM can be OUTMaintaining VDDA / 2 can be implemented by using an existing circuit, which is not limited in this embodiment and is not shown in the accompanying drawings. On this basis, the input voltage and the preset voltage of the transimpedance amplifier unit can be connected to the Flash ADC circuit, so that the Flash ADC circuit can generate a corresponding first correction control code value, thereby controlling the correction current branch to generate a corresponding correction current, so as to achieve that the input voltage of the transimpedance amplifier unit is maintained near the above-mentioned preset voltage.

[0080] Optionally, the conversion period corresponding to the correction current branch may include at least one conversion period, and the conversion period corresponding to the correction current branch may be between the conversion periods corresponding to the ambient light reduction circuit. Alternatively, the conversion period corresponding to the correction current branch may be after the conversion period corresponding to the ambient light reduction circuit.

[0081] Taking the conversion period of a correction current branch as an example, the shaded portion in the figure represents the conversion period corresponding to the correction current branch. Figure 7 The correction current conversion cycle schematic diagram shown in FIG. 1 shows that the conversion cycle of the correction current branch can be embedded between the second conversion cycle and the third conversion cycle of the ambient light reduction circuit. Figure 8 In the schematic diagram of the correction current conversion cycle shown, the conversion cycle of the correction current branch can be set after the 4th conversion cycle of the ambient light reduction circuit.

[0082] Optionally, in the conversion cycle corresponding to the correction current branch, the transresistance value adopted by the transresistance amplification unit is equal to the transresistance value of any adjacent conversion cycle. Fig. 9 , 10 In the schematic diagram of the correction current conversion cycle shown, in the conversion cycle corresponding to the correction current branch, the transresistance value can be equal to the transresistance value of 50K in the previous conversion cycle, or can also be equal to the transresistance value of 250K in the next conversion cycle.

[0083] Further optionally, the conversion cycle corresponding to the correction current branch includes a conversion cycle, and the conversion cycle corresponding to the correction current branch is adjacent to the last conversion cycle corresponding to the ambient light reduction circuit. In the conversion cycle corresponding to the correction current branch, the transresistance value used by the transresistance amplification unit is equal to the transresistance value of the last conversion cycle.

[0084] As an example, see Fig.10 The schematic diagram of the correction current conversion cycle is shown. The conversion cycle of the correction current branch can be embedded between the 3rd conversion cycle and the 4th conversion cycle of the ambient light reduction circuit. The transresistance value used is 250K. The principle is that the common mode deviation and transresistance R can be obtained through the above formula (4). F Proportional, when R FWhen switched to 250K (i.e., the transresistance value of the last conversion cycle), the common-mode deviation is the largest, and it is easy to quantize through the Flash ADC circuit, thereby improving the accuracy of quantization.

[0085] The greater the distance between the input voltage of the transimpedance amplifier unit and the above-mentioned preset voltage, the longer the settling time of the transimpedance amplifier unit in the conversion cycle. Based on the conversion cycle of the embedded correction current branch, before the ambient light reduction circuit performs the fourth conversion, the input voltage of the transimpedance amplifier unit approaches VDDA / 2, so the settling time of the transimpedance amplifier unit in the fourth conversion cycle of the ambient light reduction circuit can be shortened, thereby saving the overall conversion time of the conversion circuit.

[0086] As an example, see Fig.11 The schematic diagram of the correction current conversion cycle is shown, and the conversion cycle of the correction current branch can be set after the fourth conversion cycle of the ambient light reduction circuit, and the adopted transresistance value is 250K. If a longer transresistance amplifier unit settling time is reserved in the fourth conversion cycle, the overall conversion time of the conversion circuit can be saved.

[0087] The first feasible method for determining the binary code value of the correction current branch is introduced above, and the second feasible method will be introduced below.

[0088] In a second method, the correction control code value is estimated according to the ambient light reduction control code value. In this embodiment, the correction control code value is referred to as a second correction control code value.

[0089] Correspondingly, the conversion circuit may also be configured to: generate a second correction control code value based on the generated ambient light reduction control code value according to a preset mapping relationship, so as to control the correction current branch.

[0090] In a possible implementation, the ambient light reduction circuit may be simulated in advance, and the magnitude of the mismatch current of the ambient light reduction circuit may be estimated through the simulation result, and a mapping relationship between the ambient light reduction control code value and the second correction control code value may be set according to the estimated magnitude of the mismatch current. As an example, the mapping relationship may be "right-shifting the ambient light reduction control code value by 8 bits".

[0091] In the conversion cycle, whenever the Flash ADC circuit generates an ambient light reduction control code value, the conversion circuit can process the currently generated ambient light reduction control code value according to the above mapping relationship to obtain a second correction control code value. As an example, assuming that the number of bits of the second correction control code value is 4 bits and the number of bits of the ambient light reduction control code value is 12 bits, according to the above mapping relationship, it can be obtained that the second correction control code value is equal to the upper 4 bits of the ambient light reduction control code value.

[0092] Furthermore, the correction current branch can be controlled by the second correction control code value, so that the correction current branch can convert the received second correction control code value into a source current and a sink current to compensate for the estimated mismatch current size.

[0093] Optionally, during the debugging phase, the above-mentioned method 1 and method 2 may be used simultaneously to determine the binary code value of the correction current branch. Accordingly, the conversion circuit may also be configured as follows:

[0094] In a conversion period corresponding to the correction current branch, controlling the correction current branch based on a first correction control code value;

[0095] During a conversion period corresponding to the ambient light reduction circuit, the correction current branch is controlled based on the second correction control code value.

[0096] In one possible implementation, refer to Fig.12 The control schematic diagram of the correction current branch is shown, and the first correction control code value and the second correction control code value can be selected by the selection circuit. As an example, the selection signal of the first correction control code value can be a high-level code value "1", and the selection signal of the second correction control code value can be a low-level code value "0". The enable signal of the conversion cycle corresponding to the correction current branch can be used as the selection signal to access the selection circuit. For example, referring to Fig.10 , the conversion cycle corresponding to the correction current branch belongs to the 4th conversion cycle of the Flash ADC circuit. When the 4th conversion cycle of the Flash ADC circuit is enabled, the selection signal connected to the selection circuit can be a high-level code value "1" to select the first correction control code value; in the remaining conversion cycles, the selection signal connected to the selection circuit can be a low-level code value "0" to select the second correction control code value.

[0097] Optionally, if the minimum adjustment unit of the ambient light reduction circuit is I LSB , then the minimum adjustment unit of the correction current branch can be configured as 2*I LSB .

[0098] If the minimum adjustment unit of the ambient light reduction circuit is I LSB , refer to Figure 4 The minimum unit adjustment of the ambient light reduction circuit can be ΔOUTP = 2*I LSB *R F .

[0099] If the minimum adjustment unit of the correction current branch is 2*I LSB , refer to Figure 6 , the minimum unit adjustment of the correction current branch can be ΔVCM IN =[2*I LSB -(-2*I LSB ) / 2]*RF =2*I LSB *R F .

[0100] It can be seen that when the minimum adjustment unit of the correction current branch is 2*I LSB When the minimum unit adjustment amount of the correction current branch is the same as that of the ambient light reduction circuit, the calibration accuracy of the correction current branch and the ambient light reduction circuit can be guaranteed to be consistent.

[0101] The embodiments of the present application can achieve the following beneficial effects:

[0102] (1) The conversion circuit includes an ambient light reduction circuit and a correction current branch. While reducing the ambient light current through the ambient light reduction circuit, the correction current branch can further reduce the mismatch effect of the ambient light reduction circuit, thereby improving the reduction effect of the ambient light current.

[0103] (2) The common-mode deviation of the transimpedance amplifier unit can be reduced, thereby improving the bandwidth and gain stability of the transimpedance amplifier unit, improving the conversion accuracy of the transimpedance amplifier unit, and shortening the conversion time of the transimpedance amplifier unit.

[0104] (3) The conversion cycle of the correction current branch can be embedded in the multiple conversion cycles corresponding to the ambient light reduction circuit, thereby saving the overall conversion time of the conversion circuit.

[0105] (4) The ambient light reduction circuit and the correction current branch can share the Flash ADC circuit, saving circuit area.

[0106] The embodiment of the present application also provides a control method of a conversion circuit, which can be used to control the above conversion circuit, wherein the conversion circuit includes an ambient light reduction circuit, a correction current branch and a transimpedance amplification unit, and the ambient light reduction circuit and the correction current branch are respectively connected to the input end of the transimpedance amplification unit. Fig.13 The control method flow chart of the conversion circuit shown in FIG. 1 may include the following steps 1301-1302:

[0107] Step 1301, in a debugging stage, controlling an ambient light reduction circuit to generate a reduction current based on a current ambient light current;

[0108] Step 1302: During the debugging phase, control the correction current branch to generate a correction current.

[0109] Wherein, the correction current is used to correct the reduction current.

[0110] Optionally, the conversion circuit further includes a Flash ADC circuit;

[0111] The method further comprises:

[0112] By means of the Flash ADC circuit, in a conversion period corresponding to the ambient light reduction circuit, an ambient light reduction control code value is generated based on the output voltage of the transresistance amplifier unit to control the ambient light reduction circuit.

[0113] Optionally, the method further includes:

[0114] By means of the Flash ADC circuit, in a conversion period corresponding to the correction current branch, a first correction control code value is generated based on an input voltage of the transresistance amplifier unit and a preset voltage to control the correction current branch.

[0115] Optionally, the conversion period corresponding to the ambient light reduction circuit includes a plurality of conversion periods, and the conversion period corresponding to the correction current branch is between the conversion periods corresponding to the ambient light reduction circuit.

[0116] Optionally, the conversion period corresponding to the ambient light reduction circuit includes multiple conversion periods, and the conversion period corresponding to the correction current branch is after the conversion period corresponding to the ambient light reduction circuit.

[0117] Optionally, in each conversion cycle corresponding to the ambient light reduction circuit, the transresistance value adopted by the transresistance amplification unit is different, and the transresistance value increases in sequence according to the conversion cycle;

[0118] In the conversion cycle corresponding to the correction current branch, the transresistance value adopted by the transresistance amplification unit is equal to the transresistance value of any adjacent conversion cycle.

[0119] Optionally, the conversion period corresponding to the correction current branch includes one conversion period, and the conversion period corresponding to the correction current branch is adjacent to the last conversion period corresponding to the ambient light reduction circuit;

[0120] In the conversion cycle corresponding to the correction current branch, the transresistance value adopted by the transresistance amplification unit is equal to the transresistance value of the last conversion cycle.

[0121] Optionally, the method further includes:

[0122] According to a preset mapping relationship, a second correction control code value is generated based on the generated ambient light reduction control code value to control the correction current branch.

[0123] Optionally, the method further includes:

[0124] In a conversion period corresponding to the correction current branch, controlling the correction current branch based on a first correction control code value;

[0125] During a conversion period corresponding to the ambient light reduction circuit, the correction current branch is controlled based on a second correction control code value.

[0126] Optionally, if the minimum adjustment unit of the ambient light reduction circuit is I LSB , then the minimum adjustment unit of the correction current branch is configured as 2*I LSB .

[0127] Optionally, the method further includes:

[0128] In the conversion cycle corresponding to the ambient light reduction circuit, the output voltage of the first output end of the transresistance amplifier unit is connected to the first input end of the Flash ADC circuit, and the output voltage of the second output end of the transresistance amplifier unit is connected to the second input end of the Flash ADC circuit.

[0129] Optionally, the method further includes:

[0130] In a conversion period corresponding to the correction current branch, the input voltage of the transresistance amplification unit is connected to the first input terminal of the Flash ADC circuit, and the preset voltage is connected to the second input terminal of the Flash ADC circuit.

[0131] In an embodiment of the present application, the conversion circuit includes an ambient light reduction circuit and a correction current branch. While reducing the ambient light current through the ambient light reduction circuit, the mismatch effect of the ambient light reduction circuit can be further reduced through the correction current branch, thereby improving the reduction effect of the ambient light current.

[0132] The embodiment of the present application also provides a chip, including the conversion circuit provided in the embodiment of the present application. The chip may be, but is not limited to, a SOC (System on Chip) chip or a SIP (system in package) chip. By configuring the above-mentioned conversion circuit, the chip can reduce the ambient light current through the ambient light reduction circuit, and further reduce the mismatch effect of the ambient light reduction circuit by correcting the current branch, thereby improving the reduction effect of the ambient light current.

[0133] The embodiment of the present application also provides an electronic device, which includes a device body and a conversion circuit as described above disposed in the device body. The electronic device may be, but is not limited to, a weight scale, a body fat scale, a nutrition scale, an infrared electronic thermometer, a pulse oximeter, a human body composition analyzer, a stylus, a true wireless headset, a car central control screen, a car, a smart wearable device, a mobile terminal, and a smart home device. Smart wearable devices include, but are not limited to, smart watches, smart bracelets, and cervical massagers. Mobile terminals include, but are not limited to, smart phones, laptops, and tablet computers. Smart home devices include, but are not limited to, smart sockets, smart rice cookers, smart sweepers, and smart lights. By configuring the above-mentioned conversion circuit, the electronic device can further reduce the mismatch effect of the ambient light reduction circuit by correcting the current branch while achieving the reduction of the ambient light current through the ambient light reduction circuit, thereby improving the reduction effect of the ambient light current.

[0134] The above are only preferred embodiments of the present application, and are not intended to limit the present application in any form. Although the present application has been disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technical personnel in the field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present application. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present application without departing from the content of the technical solution of the present application are still within the scope of the technical solution of the present application.

Claims

1. A conversion circuit, characterized in that: The conversion circuit comprises an ambient light reduction circuit, a correction current branch and a transimpedance amplification unit, wherein the ambient light reduction circuit and the correction current branch are respectively connected to an input end of the transimpedance amplification unit; The ambient light reduction circuit is configured to generate a reduction current based on a current ambient light current during a commissioning phase; The correction current branch is configured to generate a correction current in the debugging phase, wherein the correction current is used to correct the clipping current.

2. The conversion circuit according to claim 1, characterized in that: The conversion circuit also includes a Flash ADC circuit, which is configured to generate a first correction control code value based on an input voltage of the transresistance amplifier unit and a preset voltage during a conversion period corresponding to the correction current branch to control the correction current branch.

3. The conversion circuit according to claim 2, characterized in that: The conversion period corresponding to the ambient light reduction circuit includes a plurality of conversion periods, and the conversion period corresponding to the correction current branch is between the conversion periods corresponding to the ambient light reduction circuit.

4. The conversion circuit according to claim 2, characterized in that: The conversion period corresponding to the ambient light reduction circuit includes a plurality of conversion periods, and the conversion period corresponding to the correction current branch is after the conversion period corresponding to the ambient light reduction circuit.

5. The conversion circuit according to claim 3 or 4, characterized in that: In each conversion cycle corresponding to the ambient light reduction circuit, the transresistance value adopted by the transresistance amplification unit is different, and the transresistance value increases in sequence according to the conversion cycle; In the conversion cycle corresponding to the correction current branch, the transresistance value adopted by the transresistance amplification unit is equal to the transresistance value of any adjacent conversion cycle.

6. The conversion circuit according to claim 5, characterized in that: The conversion period corresponding to the correction current branch includes one conversion period, and the conversion period corresponding to the correction current branch is adjacent to the last conversion period corresponding to the ambient light reduction circuit; In the conversion cycle corresponding to the correction current branch, the transresistance value adopted by the transresistance amplification unit is equal to the transresistance value of the last conversion cycle.

7. The conversion circuit according to any one of claims 2 to 4, characterized in that: The Flash ADC circuit is further configured to generate an ambient light reduction control code value based on the output voltage of the transresistance amplifier unit during a conversion period corresponding to the ambient light reduction circuit, so as to control the ambient light reduction circuit.

8. The conversion circuit according to claim 3, characterized in that: The conversion circuit is further configured as: According to a preset mapping relationship, a second correction control code value is generated based on the generated ambient light reduction control code value to control the correction current branch.

9. The conversion circuit according to claim 8, characterized in that: The conversion circuit is further configured as: In a conversion period corresponding to the correction current branch, controlling the correction current branch based on a first correction control code value; During a conversion period corresponding to the ambient light reduction circuit, the correction current branch is controlled based on a second correction control code value.

10. The conversion circuit according to claim 1, characterized in that: If the minimum adjustment unit of the ambient light reduction circuit is I LSB , then the minimum adjustment unit of the correction current branch is configured as 2*I LSB .

11. The conversion circuit according to claim 3, characterized in that: In the conversion cycle corresponding to the ambient light reduction circuit, the first input end of the Flash ADC circuit is used to receive the output voltage of the first output end of the transimpedance amplifier unit, and the second input end is used to receive the output voltage of the second output end of the transimpedance amplifier unit.

12. The conversion circuit according to claim 3, characterized in that: In the conversion period corresponding to the correction current branch, the first input terminal of the Flash ADC circuit is used to receive the input voltage of the transresistance amplification unit, and the second input terminal is used to receive the preset voltage.

13. A control method for a conversion circuit, characterized in that: The conversion circuit comprises an ambient light reduction circuit, a correction current branch and a transimpedance amplification unit, wherein the ambient light reduction circuit and the correction current branch are respectively connected to an input end of the transimpedance amplification unit; The method comprises: In the debugging stage, the ambient light reduction circuit is controlled to generate a reduction current based on the current ambient light current; In the debugging stage, the correction current branch is controlled to generate a correction current, and the correction current is used to correct the reduction current.

14. A chip, characterized in that: Comprising a conversion circuit as claimed in at least one of claims 1 to 12.

15. An electronic device, characterized in that: Comprising a conversion circuit as claimed in at least one of claims 1 to 12.

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