CN114167112B - High-precision wide-range low-voltage-difference current measurement circuit - Google Patents
High-precision wide-range low-voltage-difference current measurement circuit Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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Abstract
The invention belongs to the technical field of current measurement, and discloses a high-precision wide-range low-voltage-difference current detection circuit which comprises a microprocessor, an analog-to-digital converter and a plurality of sampling resistors, wherein each sampling resistor is provided with a corresponding output amplifier, an automatic shunt regulation module and a shunt gate; one end of the sampling resistor is connected with the current input end after being sequentially connected in series, and the other end of the sampling resistor is grounded; the input end of each output amplifier is connected with the near-current input end of the corresponding sampling resistor, the output end is connected with the analog-to-digital converter, the positive end of the automatic shunt regulation module is connected with the comparison threshold voltage vth, the negative end of the automatic shunt regulation module is connected with the near-current input end of the corresponding sampling resistor, the output end is connected with the control end of the shunt gate, one end of the shunt gate is connected with the current input end, and the other end of the shunt gate is connected with the near-current output end of the sampling resistor; the analog-to-digital converter is connected with the microprocessor, and the microprocessor is used for calculating the current value to be measured. The invention can realize a large current measuring range through automatic current diversion.
Description
Technical Field
The invention belongs to the technical field of current measurement, and particularly relates to a high-precision wide-range low-voltage-difference current detection circuit.
Background
As technology advances, electronic devices have become lower in power consumption, which may be on the nanoampere level at low power consumption, but may be on the ampere level at high power consumption. To measure such currents, a wide-range analog-to-digital converter is required, for example, a 30-bit ADC is required to realize nA-a span current measurement, no ADC with such high bit number is available on the market, and as the number of bits of the ADC conversion result increases, the conversion time of the ADC is longer, so that it is impossible to realize high-speed sampling of the wide-range current by using a sampling resistor. In addition, when some sensor physical quantity detection is realized, current change is large, and high-precision measurement of wide-range current is also required.
The existing resistance switching schemes are realized by judging that the measuring result exceeds the measuring range and switching the sampling resistor through a pin, the mode needs program execution cooperation of the processor, the switching time cannot be fast, and if the current changes severely, the acquired data are invalid and cannot reflect the actual change of the current. In addition, the plurality of switches and resistors are connected in parallel, the more the number of sampling resistor stages is, the larger the corresponding number of switching stages is, the larger the sampling voltage drop is, and the field with strict requirements on the sampling voltage drop cannot be adapted.
Disclosure of Invention
In order to adapt to the actual demands in the technical field of current measurement, the invention overcomes the defects existing in the prior art, and solves the technical problems that: the current detection circuit with high precision, wide range and low voltage difference is provided to realize wide range and high precision current measurement.
In order to solve the technical problems, the invention adopts the following technical scheme: a high precision wide range low dropout current measurement circuit comprising: the system comprises a microprocessor, an analog-to-digital converter and a plurality of sampling resistors R1-RN, wherein each sampling resistor is provided with a corresponding output amplifier, an automatic shunt regulation module and a shunt gate;
One end of each of the sampling resistors R1-RN is connected with the current input end after being sequentially connected in series, the other end of each of the sampling resistors is grounded, the sampling resistor R1 is arranged at the current input end, and the sampling resistor Rn is arranged at the grounding end; n is more than or equal to 2, and represents the number of sampling resistors; r1 > R2 … … > RN;
The positive input end of each output amplifier corresponding to the sampling resistor is connected with the near-current input end of the sampling resistor, the output end of each output amplifier is connected with the analog-to-digital converter, the automatic shunt regulating module comprises an operational amplifier, the positive end of the operational amplifier is connected with the comparison threshold voltage vth, the negative end of the operational amplifier is connected with the near-current input end of the corresponding sampling resistor, the output end of the operational amplifier is connected with the control end of the shunt gate, one end of the shunt gate is connected with the current input end, and the other end of the shunt gate is connected with the near-current output end of the corresponding sampling resistor;
The output end of the analog-to-digital converter is connected with the microprocessor, and the microprocessor is used for judging the state of each shunt gate according to the output voltage of the analog-to-digital converter, so as to calculate the current value to be measured.
The sampling resistor satisfies the following conditions:
Rn-1/Rn＝Y，n＝1……N；
wherein Y represents a proportionality constant greater than 1.
The value of Y is 10.
The shunt gate comprises an NMOS tube or a PMOS tube, and the grid electrode of the shunt gate is connected with the output end of the corresponding operational amplifier.
The shunt gate comprises a plurality of NMOS tubes or a plurality of PMOS tubes, and the grid electrode of the shunt gate is connected with the output end of the corresponding operational amplifier.
When the shunt gate comprises a plurality of NMOS tubes or PMOS tubes, the drains of the NMOS tubes or the PMOS tubes are connected together, the sources are connected together, and the grids are connected together.
When the shunt gate is an NMOS tube, the drain electrode of the shunt gate is connected with the current input end, and the source electrode of the shunt gate is connected with the near current output end of the corresponding sampling resistor;
when the shunt gate is a PMOS tube, the source electrode is connected with the current input end, and the drain electrode is connected with the near current output end of the corresponding current sampling resistor.
The microprocessor judges the states of the shunt gates according to the output voltage of the analog-to-digital converter, and further calculates the current value, wherein the method comprises the following specific steps:
S1, judging whether the output voltage V1 of the output amplifier corresponding to the sampling resistor R1 is smaller than vth X T X, if yes, determining that the current i=V1/X/(R1+R2+ … … +RN) to be detected, and if no, entering a step S2;
S2, judging whether the output voltage V2 of the output amplifier corresponding to the sampling resistor R2 is smaller than vth X T X, if yes, enabling the circuit i=V2/X/(R2+ … … +RN) to be tested, and if not, entering a step S3;
s3, judging whether the output voltage V3 of the output amplifier corresponding to the sampling resistor R3 is smaller than vth X T X, if yes, the current i=v3/X/(R3+ … … +RN) to be measured; if not, entering step S4;
……
SN, judging whether the output voltage VN of the output amplifier corresponding to the sampling resistor RN is smaller than vth×t×x, if yes, the current i=v3/X/(RN) to be measured; wherein X represents the amplification factor of the output amplifier and T represents the safety factor.
The positive end of the output amplifier is connected with the near-current input end of the corresponding sampling resistor, the negative end of the output amplifier is grounded through the resistor, and a feedback resistor is connected between the output end and the negative end.
The number N of the sampling resistors is 2-10.
Compared with the prior art, the invention has the following beneficial effects:
1. The invention provides a high-precision wide-range low-voltage difference current detection circuit, and an automatic shunt regulating circuit compares the voltage on a corresponding sampling resistor with a preset threshold voltage, so that the opening and closing degree of a shunt gate is automatically controlled, the automatic shunt of current is realized, and the high-speed switching of current sampling resistors with different resistance values is realized. When measuring a large current, the sampling voltage of the small sampling resistor is taken as an effective output. Thus, an arbitrarily large current measurement range can be realized, and the theoretical measuring range is limited only by input noise output by the amplifier and input end current.
2. The automatic shunt regulating module can set the sampling voltage drop of the whole circuit, and ensure that the total current sampling voltage drop of the circuit does not exceed a preset threshold value in the whole current range.
3. The invention adopts a simple automatic circuit to switch the sampling resistor at high speed, can control the overall sampling voltage drop of the circuit, can meet the measurement requirement of high-speed wide-range current, does not need to change the sampling rear end, has low cost, high reliability and wide implementation, can realize wide-range high-precision measurement of the current, and can be widely applied to a plurality of fields.
Drawings
FIG. 1 is a schematic circuit diagram of a high-precision wide-range low-voltage-difference current detection circuit according to a first embodiment of the present invention;
FIG. 2 is a schematic circuit diagram of a high-precision wide-range low-voltage-difference current detection circuit according to a second embodiment of the present invention;
Fig. 3 is a schematic circuit diagram of a high-precision wide-range low-voltage-difference current detection circuit according to a third embodiment of the present invention.
Description of the preferred embodiments
In order to make the technical solution and advantages of the present invention more apparent, a technical solution of the present invention will be clearly and completely described below with reference to specific embodiments and drawings, it being apparent that the described embodiments are some but not all embodiments of the present invention; all other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
As shown in fig. 1, the first embodiment of the invention provides a high-precision wide-range low-dropout current measurement circuit, which comprises a sampling resistor R1, a sampling resistor R2, an operational amplifier U4, an output amplifier U1, an output amplifier U3, a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, an analog-to-digital converter U5 and a microprocessor. The sampling resistor R1 corresponds to the operational amplifier U2, the MOS tube Q1 and the output amplifier U1, and the sampling resistor R2 corresponds to the operational amplifier U4, the output amplifier U3, the MOS tube Q2 and the MOS tube Q3.
One end of each sampling resistor R1 and one end of each sampling resistor R2 are connected with the current input end in series in sequence, the other end of each sampling resistor R1 is grounded, the sampling resistor R1 is arranged at the current input end, and the sampling resistor R2 is arranged at the grounding end.
The input end of each output amplifier corresponding to the sampling resistor is connected with the near-current input end of the sampling resistor, the output end of each output amplifier is connected with the analog-to-digital converter U5, the positive end of the operational amplifier is connected with the comparison threshold voltage vth, the negative end of the operational amplifier is connected with the near-current input end of the corresponding sampling resistor, the output end of the operational amplifier is connected with the control end of the corresponding MOS tube, one end of the MOS tube is connected with the current input end, and the other end of the MOS tube is connected with the near-current output end of the corresponding sampling resistor. The output end of the analog-to-digital converter is connected with the microprocessor, and the microprocessor is used for judging the state of each shunt gate according to the output voltage of the analog-to-digital converter, so as to calculate the current value to be measured. In this embodiment, the operational amplifiers U2 and U4 are used as automatic shunt adjustment modules, which automatically adjust the opening of the shunt gate, that is, automatically adjust the current path, by comparing a fixed voltage threshold with the voltage of the near current input end of the corresponding sampling resistor, so as to realize the automatic high-speed switching of the sampling resistor;
Specifically, the MOS transistors Q1, Q2, and Q3 may be NMOS transistors or PMOS transistors, and gates thereof are connected to output ends of the corresponding operational amplifiers. When the MOS tube is an NMOS tube, the drain electrode of the MOS tube is connected with the near-current input end of the sampling resistor R1, and the source electrode of the MOS tube is connected with the near-current output end of the corresponding sampling resistor; when the MOS tube is a PMOS tube, the source electrode is connected with the near-current input end of the sampling resistor R1, and the drain electrode is connected with the near-current output end of the corresponding current sampling resistor.
In this embodiment, the sampling resistor R2 corresponds to 2 MOS transistors (Q2 and Q3), the drains of the two MOS transistors are connected together, the sources are connected together, and the gates are connected together.
Specifically, in this embodiment, the sampling resistor satisfies the following condition:
R2/R1＝Y； (1)
wherein Y represents a proportionality constant greater than 1.
Specifically, in this embodiment, if the value of Y is 10, the resistance values of the sampling resistors R1 and R2 may be 1k ohms and 100 ohms, or 100 ohms and 10 ohms.
Example two
As shown in fig. 2, the second embodiment of the present invention provides a high-precision wide-range low-dropout current measurement circuit, which includes a sampling resistor R1, a sampling resistor R2, a sampling resistor R3, an operational amplifier U2, an operational amplifier U4, an operational amplifier U6, an output amplifier U1, an output amplifier U3, and an output amplifier U5, a MOS transistor Q1, a MOS transistor Q2, a MOS transistor Q3, a MOS transistor Q4, a MOS transistor Q5, an analog-to-digital converter U5, and a microprocessor. The sampling resistor R1 corresponds to the operational amplifier U2, the MOS tube Q1 and the output amplifier U1, the sampling resistor R2 corresponds to the operational amplifier U4, the output amplifier U3 and the MOS tube Q2, and the sampling resistor R3 corresponds to the operational amplifier U6, the output amplifier U5 and the MOS tubes Q5 to Q5.
One end of each sampling resistor R1, R2 and R3 is connected with the current input end after being sequentially connected in series, the other end of each sampling resistor is grounded, the sampling resistor R1 is arranged at the current input end, and the sampling resistor R3 is arranged at the grounding end.
The input end of each output amplifier corresponding to the sampling resistor is connected with the near-current input end of the corresponding sampling resistor, the output end of each output amplifier is connected with the analog-to-digital converter U5, the positive end of the operational amplifier is connected with the comparison threshold voltage vth, the negative end of the operational amplifier is connected with the near-current input end of the corresponding sampling resistor, the output end of the operational amplifier is connected with the control end of the corresponding MOS tube, one end of the MOS tube is connected with the current input end, and the other end of the MOS tube is connected with the near-current output end of the corresponding sampling resistor. The output end of the analog-to-digital converter is connected with the microprocessor, and the microprocessor is used for judging the state of each shunt gate according to the output voltage of the analog-to-digital converter, so as to calculate the current value to be measured.
Specifically, the MOS transistors Q1 to Q5 may be NMOS transistors or PMOS transistors, and gates thereof are connected to output ends of the corresponding operational amplifiers. When the MOS tube is an NMOS tube, the drain electrode of the MOS tube is connected with the current input end, and the source electrode of the MOS tube is connected with the near current output end of the corresponding sampling resistor; when the MOS tube is a PMOS tube, the source electrode is connected with the current input end, and the drain electrode is connected with the near current output end of the corresponding current sampling resistor.
In this embodiment, the sampling resistor R3 corresponds to 3 MOS transistors (Q3 to Q5), the drains of the two MOS transistors are connected together, the sources are connected together, and the gates are connected together.
Specifically, in this embodiment, the sampling resistor satisfies the following condition:
R3/R2＝R2/R1＝Y； (2)
wherein Y represents a proportionality constant greater than 1.
Specifically, in this embodiment, if the value of Y is 10, the resistance values of the sampling resistors R1 to R3 may be 1k ohm, 100 ohm, and 10 ohm.
As shown in fig. 3, in this embodiment, the operational amplifiers U2, U4, and U6 form an automatic shunt adjustment function, which is called an automatic shunt adjustment module, the MOS transistors Q1 to Q5 implement a shunt gate function, and the output amplifiers U1, U3, and U5 are used to implement an output signal amplifying function. The analog-to-digital converter U5 is used for realizing analog-to-digital conversion, and is convenient for the microprocessor to perform data operation.
The maximum sampling voltage drop of the whole circuit is set to be vth, and the voltage is generated by a specific voltage dividing circuit. The resistance value of the sampling resistor satisfies the condition: r1 > R2 > R3, and the following relation R1/R2 = R2/R3 = Y is provided for the resistance, the amplification factors of the amplifier outputs U1, U3 and U5 are unified as X, and the vth X is ensured not to be larger than the maximum input voltage of the analog-digital converter ADC. In addition, a safety factor T, here set to 0.8, needs to be set. The analog-digital converter ADC determines that the corresponding shunt gate of the sampling resistor is closed as long as it detects that the corresponding amplifier output signal of the sampling resistor of a certain stage is smaller than th×x×0.8, and the sampling voltage of the sampling resistor is valid, i.e. the output of the corresponding amplifier output is valid.
1. In this embodiment, the automatic shunt adjustment function is mainly implemented by an operational amplifier. The specific working principle is as follows: the positive end of the operational amplifier (U2, U4, U6) is connected with the comparison threshold voltage vth, and the negative end of the operational amplifier is connected with the near-current input end of the corresponding sampling resistor. When the voltage v on the corresponding sampling resistor is smaller than vth, if v=vth 0.8, the output of the operational amplifier is high, the corresponding MOS tube is completely closed, and at the moment, the voltage between the source electrode and the drain electrode of the MOS tube is smaller than vth, the leakage current of the MOS tube is extremely small, and the current can be considered to flow through the corresponding sampling resistor completely, and the output of the corresponding amplifier is effective. When the current is gradually increased, the voltage at the negative end of the corresponding operational amplifier is increased, the output voltage of the operational amplifier is reduced, and the corresponding MOS tube is gradually opened. When the MOS tube is gradually opened, the current flowing through the MOS tube is gradually increased, and the current flowing through the corresponding resistor is basically unchanged. It can be known that the automatic current-dividing and adjusting module in the embodiment realizes automatic current dividing, and the current flowing path changes along with the current, so that the purpose that a large current flows through a small resistor and a small current flows through a large resistor is realized. Namely, when measuring small current, the sampling voltage of the large sampling resistor is taken as effective output; when measuring a large current, the sampling voltage of the small sampling resistor is taken as an effective output. Thus, an arbitrarily large current measurement range can be realized, and the theoretical measuring range is limited only by input noise output by the amplifier and input end current. In addition, the overall voltage drop of the circuit is also controlled by automatic shunt regulation of the comparison voltage, which is the core component of the present invention.
The current enters the circuit from the current input, set to i.
If i (r1+r2+r3) < vth 0.8, the output of the operational amplifiers U2, U4, R6 is high, the controlled MOS transistors Q1, Q2, Q3, Q4, Q5 are all in the off state, and at this time, the output of the amplifier output U1 is v1=i (r1+r2+r3) ×x, the processor obtains the voltage value v1< vth 0.8×x through the analog-to-digital converter ADC, and then the current i=v1/X/(r1+r2+r3) to be measured is calculated.
If i (r1+r2+r3) > vth 0.8, the processor obtains the output voltage v1=i (r1+r2+r3) ×v1×0.8×x of U1 through the ADC, the output state of U2 is uncertain, that is, it is uncertain whether Q1 has started to be turned on, and a part of current may flow through Q1. Then, the voltage value v2=i (r2+r3) X after the voltage on R2 is amplified by U3 is continuously obtained, if i (r2+r3) < vth 0.8, it is determined that the shunt gate corresponding to the sampling resistor R2 is not opened, that is, all the currents to be measured flow through R2 and R3, and the current V2/X/(r2+r3) can be calculated.
By analogy, the microprocessor collects the voltages output by all the amplifiers through the analog-to-digital converter ADC, and calculates from the sampling resistor at the near current input end, if the output V < vth > of the output of the amplifier is 0.8 x, the current value is V/Rsum (Rsum represents the sum of the corresponding sampling resistor and all the sampling resistors below); if the output V of the amplifier output is greater than vth 0.8 x, the next sampling resistor is seen to correspond to the output of the amplifier output, and the current to be measured can be calculated because the sampling resistor is smaller and the output of one amplifier output is smaller than vth 0.8 x.
Further, in this embodiment, the positive end of the output amplifier is connected to the near-current input end of the corresponding sampling resistor, the negative end is grounded through the resistor, and a feedback resistor is connected between the output end and the negative end. In this embodiment, three PMOS transistors are schematically used for the shunt gate corresponding to the sampling resistor R3, because when the current is relatively large, the MOS transistor has an internal resistance, and a corresponding voltage drop is generated when the current flows. Therefore, the parallel MOS tube can reduce the sampling voltage drop of the circuit under the condition of large current.
Further, in this embodiment, only three sampling resistors and their corresponding amplifier outputs, automatic shunt adjustments and shunt gates are provided. In practical application, more stages of sampling resistors and corresponding circuits can be arranged according to the current range requirement to be measured. That is, the number of the sampling resistors may be four or more, for example, 10.
Assuming that sampling resistors R1-RN are sequentially connected in series, one end of each sampling resistor is connected with a current input end, the other end of each sampling resistor is grounded, the sampling resistor R1 is arranged at the current input end, and the sampling resistor Rn is arranged at the grounding end; preferably, each sampling resistor satisfies the following condition:
Rn-1/Rn＝Y，n＝1……N； (3)
wherein Y represents a proportionality constant greater than 1.
It should be noted that, in the present invention, the ratio of the resistance values of two adjacent sampling resistors may also be different, and may be set according to the actual measurement requirement, and according to the teaching of the foregoing specification, those skilled in the art may know that, in the present invention, the ratio of the resistance values of two adjacent sampling resistors corresponds to the multiple relationship between the corresponding measuring ranges.
Further, in this embodiment, assuming that the number of sampling resistors is N, the specific steps for the microprocessor to calculate the current value are as follows:
S1, judging whether the output voltage V1 of the output amplifier corresponding to the sampling resistor R1 is smaller than vth X T X, if yes, determining that the current i=V1/X/(R1+R2+ … … +RN) to be detected, and if no, entering a step S2;
S2, judging whether the output voltage V2 of the output amplifier corresponding to the sampling resistor R2 is smaller than vth X T X, if yes, enabling the circuit i=V2/X/(R2+ … … +RN) to be tested, and if not, entering a step S3;
s3, judging whether the output voltage V3 of the output amplifier corresponding to the sampling resistor R3 is smaller than vth X T X, if yes, the current i=v3/X/(R3+ … … +RN) to be measured; if not, entering step S4;
……
SN, judging whether the output voltage VN of the output amplifier corresponding to the sampling resistor RN is smaller than vth×t×x, if yes, the current i=v3/X/(RN) to be measured; where X represents the amplification factor of the output amplifier, T represents the safety factor, and can be set to 0.8 or other constant.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (6)
1. A high precision wide range low dropout current measurement circuit, comprising: the system comprises a microprocessor, an analog-to-digital converter and a plurality of sampling resistors R1-RN, wherein each sampling resistor is provided with a corresponding output amplifier, an automatic shunt regulation module and a shunt gate;
One end of each of the sampling resistors R1-RN is connected with the current input end after being sequentially connected in series, the other end of each of the sampling resistors is grounded, the sampling resistor R1 is arranged at the current input end, and the sampling resistor Rn is arranged at the grounding end; n is more than or equal to 2, and represents the number of sampling resistors; r1 > R2 … … > RN;
The positive input end of each output amplifier corresponding to the sampling resistor is connected with the near-current input end of the sampling resistor, the output end of each output amplifier is connected with the analog-to-digital converter, the automatic shunt regulating module comprises an operational amplifier, the positive end of the operational amplifier is connected with the comparison threshold voltage vth, the negative end of the operational amplifier is connected with the near-current input end of the corresponding sampling resistor, the output end of the operational amplifier is connected with the control end of the shunt gate, one end of the shunt gate is connected with the current input end, and the other end of the shunt gate is connected with the near-current output end of the corresponding sampling resistor;
The output end of the analog-to-digital converter is connected with the microprocessor, and the microprocessor is used for judging the state of each shunt gate according to the output voltage of the analog-to-digital converter so as to calculate a current value to be measured;
The shunt gate comprises an NMOS tube or a PMOS tube, and the grid electrode of the shunt gate is connected with the output end of the corresponding operational amplifier; or the shunt gate comprises a plurality of NMOS tubes or a plurality of PMOS tubes, and the grid electrode of the shunt gate is connected with the output end of the corresponding operational amplifier;
When the shunt gate is an NMOS tube, the drain electrode of the shunt gate is connected with the current input end, and the source electrode of the shunt gate is connected with the near current output end of the corresponding sampling resistor; when the shunt gate is a PMOS tube, the source electrode of the shunt gate is connected with the current input end, and the drain electrode of the shunt gate is connected with the near current output end of the corresponding current sampling resistor;
The microprocessor judges the states of the shunt gates according to the output voltage of the analog-to-digital converter, and further calculates the current value, wherein the specific steps are as follows:
S1, judging whether the output voltage V1 of the output amplifier corresponding to the sampling resistor R1 is smaller than vth X T X, if yes, determining that the current i=V1/X/(R1+R2+ … … +RN) to be detected, and if no, entering a step S2;
S2, judging whether the output voltage V2 of the output amplifier corresponding to the sampling resistor R2 is smaller than vth X T X, if yes, enabling the circuit i=V2/X/(R2+ … … +RN) to be tested, and if not, entering a step S3;
s3, judging whether the output voltage V3 of the output amplifier corresponding to the sampling resistor R3 is smaller than vth X T X, if yes, the current i=v3/X/(R3+ … … +RN) to be measured; if not, entering step S4;
……
SN, judging whether the output voltage VN of the output amplifier corresponding to the sampling resistor RN is smaller than vth×t×x, if yes, the current i=v3/X/(RN) to be measured; wherein X represents the amplification factor of the output amplifier and T represents the safety factor.
2. The high precision wide range low dropout current measurement circuit according to claim 1, wherein said sampling resistor satisfies the following condition:
Rn-1/Rn＝Y，n＝1……N；
wherein Y represents a proportionality constant greater than 1.
3. The high-precision wide-range low-dropout current measurement circuit according to claim 2, wherein said Y has a value of 10.
4. The high-precision wide-range low-dropout current measurement circuit according to claim 1, wherein when said shunt gate includes a plurality of NMOS transistors or a plurality of PMOS transistors, drains of the respective NMOS transistors or PMOS transistors are connected together, sources thereof are connected together, and gates thereof are connected together.
5. The high-precision wide-range low-dropout current measurement circuit according to claim 1, wherein the positive terminal of the output amplifier is connected with a near-current input terminal of a corresponding sampling resistor, the negative terminal is grounded via a resistor, and a feedback resistor is connected between the output terminal and the negative terminal.
6. The high-precision wide-range low-dropout current measurement circuit according to claim 1, wherein the number N of said sampling resistors is 2 to 10.
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| CN202111541523.3A Active CN114167112B (en) | 2021-12-16 | 2021-12-16 | High-precision wide-range low-voltage-difference current measurement circuit |
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| CN114167112A (en) | 2022-03-11 |
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