A current logarithmic measuring instrument

Abstract

The present invention discloses a current logarithmic measuring instrument, which comprises at least two parts: a current mirror hybrid array circuit and a logarithmic measurement circuit. The current mirror array circuit is composed of a set of main loop current mirrors and multiple sets of sub-loop current mirrors in hybrid connection. The logarithmic measurement circuit is composed of a logarithmic amplifier and its peripheral circuits. The present invention is suitable for high-precision current measurement over an ultra-wide range and can continuously measure no less than 7 orders of magnitude (for example, 10 ‑7 ~10 ‑1 A) current range, filling the gap in the demand for precise current measurement in high-precision and cutting-edge industries.

Description

Technical Field

[0001] The invention belongs to the field of current measurement and relates to a current logarithm measuring instrument, which is a high-performance current measuring device. Background Art

[0002] At present, in many high-tech industries (such as scientific research, medical treatment, semiconductor industry, etc.) such as semiconductor material impedance test, metal oxide electrochemical property test, insulation material impedance test, wearable electronic device power consumption test, battery leakage current test, etc., there is an urgent need for a tester that can span multiple orders of magnitude, generally requiring no less than 7 orders of magnitude (for example, 10 -7 ~10 -1 A) continuous current measuring instrument, and it is required that the measurement cannot be interrupted or switched during the measurement. In the existing technical solution, since the logarithmic amplifier can process the analog signal spanning 7 orders of magnitude into a narrow range of logarithmic analog signals, it can be used for A / D converter to perform digital processing and finally obtain the current value. However, since the typical input range of the existing logarithmic amplifier is only 10 -12 ~3×10 -3 A, this range cannot meet the actual needs, and it is necessary to perform a proportional offset with high precision, wide range and fast dynamic response.

[0003] In the prior art, a resistor shunt is generally used to measure current. However, its disadvantage is that when the measured current changes across orders of magnitude, its consumption voltage also changes across orders of magnitude. For example, when the measured current changes from 10 -7 A to 10 -1 When A changes, the consumed voltage changes by a factor of one million. This results in high losses and severe heat generation at high currents, and low signal-to-noise ratio, high noise, and slow dynamic response at low currents. Consequently, there is currently no effective technical solution on the market to meet the demands of high-tech industries for precise current measurement.

[0004] The present invention proposes for the first time a precise current measurement based on a multiple current mirror hybrid circuit, which can continuously measure not less than 7 orders of magnitude (for example, 10 -7 ~10 -1 The current range of A) solves the scaling problem of current signal with high precision, wide range and fast dynamic response, thus filling the gap in the precision current measurement needs of high-end industries. Summary of the Invention

[0005] The purpose of the present invention is to address the deficiencies of the existing technology and provide a current logarithmic measuring instrument. Through an original multiple current mirror hybrid array circuit, the input current is precisely amplified / reduced, and then a logarithmic amplifier is used to perform logarithmic conversion. The analog voltage is output to the A / D conversion terminal to form a digitized voltage value. The voltage value is processed by algorithms such as linear interpolation, polynomial interpolation, and Gaussian fitting to obtain the final precise current value.

[0006] The present invention provides a current logarithmic measuring instrument, which comprises at least a current mirror hybrid array circuit and a logarithmic measurement circuit, wherein:

[0007] The current mirror hybrid array circuit includes a group of main loop current mirrors and N groups of sub-loop current mirrors, where N is greater than or equal to 1. The main loop current mirror is used to obtain original measured current information. The sub-loop current mirrors are shunt or current doubling current mirrors, which are used to mirror the current in the main loop current mirror to perform shunt or current doubling operations, thereby achieving precise amplification or reduction of the measured current.

[0008] The logarithmic measurement circuit uses a logarithmic amplifier to perform logarithmic conversion on the current mirror hybrid array circuit, and outputs it in the form of an analog voltage to the A / D conversion terminal to form a digitized voltage value. After the voltage value is processed by linear interpolation, polynomial interpolation, and Gaussian fitting algorithms, the final precise current value is obtained.

[0009] Preferably, the hybrid connection includes one or more combinations of series connection, parallel connection and staggered connection.

[0010] Preferably, if the sub-loop current mirror is a shunt mirror, the main loop current mirror includes n NPN transistors, n≥2; the bases of all NPN transistors are connected together, and the emitters are grounded; the collector of one NPN transistor serves as the output end of the main loop current mirror, and the collectors of the remaining NPN transistors are connected as the input end of the main loop current mirror, for inputting the measured current; the sub-loop current mirror includes m PNP transistors, m≥2; the bases of all PNP transistors are connected together, and the emitters are connected to VCC; the collector of one PNP transistor serves as the output end of the sub-loop current mirror, and the collectors of the remaining PNP transistors are connected as the input end of the sub-loop current mirror, for connecting to the output end of the main loop current mirror.

[0011] Preferably, if the sub-loop current mirror is a current doubler mirror, the main loop current mirror includes n NPN transistors, n≥2; the bases of all NPN transistors are connected together, and the emitters are grounded; the collector of one of the NPN transistors serves as the input end of the main loop current mirror, for inputting the measured current, and the collectors of the remaining NPN transistors are connected as the output end of the main loop current mirror; the sub-loop current mirror includes m PNP transistors, m≥2; the bases of all PNP transistors are connected together, and the emitters are connected to VCC; the collector of one of the PNP transistors serves as the input end of the sub-loop current mirror, for connecting to the output end of the main loop current mirror, and the collectors of the remaining PNP transistors are connected as the output end of the sub-loop current mirror.

[0012] The beneficial effects of the present invention are:

[0013] The present invention adopts hybrid connection between sub-circuits and hybrid connection between main circuit and sub-circuits, emphasizing the diversity of connection methods. Different connection methods are adapted to different needs and produce different current ratios. The present invention is suitable for high-precision current measurement over an ultra-wide range and can continuously measure no less than 7 orders of magnitude (for example, 10 -7 ~10 -1 The current range of A) solves the scaling problem of current signal with high precision, wide range and fast dynamic response, thus filling the gap in the precision current measurement needs of high-end industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a simplified circuit diagram of the present invention;

[0015] Figure 2 This is a circuit structure diagram of Example 1 of the present invention;

[0016] Figure 3 This is a circuit structure diagram of Example 2 of the present invention;

[0017] Figure 4 This is a circuit structure diagram of Example 3 of the present invention;

[0018] Figure 5 This is a circuit structure diagram of embodiment 4 of the present invention. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. The embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0020] like Figure 2 As shown, this embodiment 1 provides a current logarithmic measuring instrument, including a current mirror hybrid array circuit and a logarithmic measurement circuit, wherein the current mirror hybrid array circuit includes a main loop current mirror and a shunt current mirror connected in series.

[0021] The main loop current mirror includes three NPN transistors QQ2A, QQ2B, and QQ2C; the bases of the three NPN transistors QQ2A, QQ2B, and QQ2C are connected together; the collector of the NPN transistor QQ2A and the collector of the NPN transistor QQ2B are connected as the input end of the main loop current mirror, for inputting the measured current; the emitters of the three NPN transistors QQ2A, QQ2B, and QQ2C are all grounded; the collector of QQ2C serves as the output point of the main loop current mirror.

[0022] The shunt current mirror includes three PNP transistors QQ1A, QQ1B, and QQ1C. The bases of the three PNP transistors QQ1A, QQ1B, and QQ1C are connected together and connected to the collectors of the PNP transistor QQ1A and the collectors of the PNP transistor QQ1B. At the same time, these bases serve as the input end of the shunt current mirror and are used to connect to the output end of the main loop current mirror; the emitters of the three PNP transistors QQ1A, QQ1B, and QQ1C are connected to VCC, and the collector of the PNP transistor QQ1C serves as the output end of the shunt current mirror and is used to connect to the input end of the logarithmic measurement circuit.

[0023] The logarithmic measurement circuit includes a logarithmic amplifier, an A / D converter, a capacitor C, and a resistor R; one input terminal of the logarithmic amplifier is connected to the measured voltage output by the current mirror hybrid array circuit, the other input terminal is connected to one end of the capacitor C and the output of the precision reference current source, and the output terminal is connected to the other end of the capacitor C, one end of the resistor R, and the input terminal of the A / D converter; the output terminal of the A / D converter outputs a digital voltage; the other end of the resistor R is connected to a negative voltage.

[0024] exist Figure 2 Based on Figure 3 As shown, this embodiment 2 provides another current logarithmic measuring instrument, including a current mirror hybrid array circuit and a logarithmic measurement circuit. The current mirror hybrid array circuit includes a main loop current mirror and a current doubling current mirror connected in series.

[0025] The main loop current mirror includes three NPN transistors QQ2A, QQ2B, and QQ2C; the bases of the three NPN transistors QQ2A, QQ2B, and QQ2C are connected together; the collectors of the NPN transistor QQ2B and the NPN transistor QQ2C are connected and serve as the output end of the main loop current mirror; the emitters of the three NPN transistors QQ2A, QQ2B, and QQ2C are all grounded; the collector of the NPN transistor QQ2A serves as the input end of the main loop current mirror, for inputting the measured current.

[0026] The current-doubling current mirror includes three PNP transistors QQ1A, QQ1B, and QQ1C. The bases of the three PNP transistors QQ1A, QQ1B, and QQ1C are connected together and connected to the collectors of the PNP transistor QQ1B and the collectors of the PNP transistor QQ1C. At the same time, these bases serve as the output end of the current-doubling current mirror and are connected to the input end of the logarithmic measurement circuit. The emitters of the three PNP transistors QQ1A, QQ1B, and QQ1C are all connected to VCC. The collector of the PNP transistor QQ1A serves as the input end of the current-doubling current mirror and is used to connect to the output end of the main loop current mirror. The logarithmic measurement circuit and Figure 2 The embodiments are the same and will not be described again.

[0027] This implementation example 3 Figure 3 Based on Figure 4 As shown in the figure, it further shows the situation of the current doubler current mirror in parallel. Two transistors are added, namely NPN transistor QQ1D and PNP transistor QQ2D. The base, collector and emitter of QQ1D and QQ1C are connected in parallel respectively, while the base, collector and emitter of QQ2D and QQ2C are connected in parallel respectively. In this case, the current doubler is increased.

[0028] This implementation example 4 Figure 2 Based on Figure 5 The figure further illustrates the case of connecting more current mirrors in parallel with the current shunt mirror. This also adds a PNP transistor QQ2D and an NPN transistor QQ1D. The connection is changed to connect QQ2C in parallel with QQ2A and QQ2B, respectively. Only the base and emitter of QQ2D are connected in parallel with the aforementioned transistors, with the collector serving as the output. Similarly, QQ1C is connected in parallel with QQ1A and QQ1B, while only the base and collector of QQ1D are connected in parallel with the aforementioned transistors, with the collector serving as the output. This reduces the current shunt ratio.

[0029] Generally speaking, current doublers and shunts are similar in that the bases and emitters of all transistors are connected together; the difference lies in the different collector connections. If most collectors are connected to the input, it's a shunt, while if most collectors are connected to the output, it's a current doubler. Furthermore, the amplification factor / divider ratio of the current doubler / divider depends on the number of transistors. Increasing the number of transistors increases the amplification factor of a current doubler, while decreasing the amplification ratio of a current shunt, and vice versa.

[0030] The current logarithmic measuring instrument proposed in Example 4 of the present invention is 10 -7 ~10 -1 The relative error within the A range does not exceed 1%, the dynamic response time is no more than 10usec, the temperature drift does not exceed 100PPM, and the consumption voltage variation range is between 0.5 and 0.8V. This proves that the present invention solves the shortcomings of the existing technology in ultra-wide range current measurement applications and achieves the technical level of ultra-high precision, ultra-fast dynamic response speed and ultra-low temperature drift, thus filling the gap in the demand for precision current measurement in high-end industries.

[0031] Table 1 Experimental measurement data

[0032] Measured current (A) Measured current (A) Relative error (%) Response time (usec) Temperature drift (0~50℃) Consumption voltage 100n 100.6n 0.6 7.9 80PPM 0.52V 1u 1.007u 0.7 4.3 80PPM 0.55V 10u 9.996u -0.4 3.9 70PPM 0.56V 100u 100.2u 0.2 3.3 80PPM 0.59V 1m 1.003m 0.3 2.5 60PPM 0.66V 10m 9.999m -0.1 2.4 60PPM 0.67V 100m 100.3m 0.3 2.4 70PPM 0.71V

Claims

1. A current logarithmic measuring instrument, suitable for measuring a current range of not less than 7 orders of magnitude, comprising at least a current mirror hybrid array circuit and a logarithmic measurement circuit, wherein the logarithmic measurement circuit uses a logarithmic amplifier to perform logarithmic conversion on the current mirror hybrid array circuit and outputs the analog voltage to an A / D conversion terminal to form a digitized voltage value. After processing, the voltage value is used to obtain a final precise current value; characterized in that: The current mirror hybrid array circuit includes a group of main loop current mirrors and N groups of sub-loop current mirrors, where N is greater than or equal to 1. The main loop current mirror is used to obtain original measured current information. The sub-loop current mirrors are shunt or current doubling current mirrors, which are used to mirror the current in the main loop current mirror to perform shunt or current doubling operations, thereby achieving precise amplification or reduction of the measured current. The hybrid connection adopts one or more combinations of series connection, parallel connection and staggered connection.

2. A current logarithmic measuring instrument according to claim 1, characterized in that If the sub-loop current mirror is a shunt mirror, the main loop current mirror includes n NPN transistors, n≥2; the bases of all NPN transistors are connected together, and the emitters are grounded; the collector of one of the NPN transistors serves as the output end of the main loop current mirror, and the collectors of the remaining NPN transistors are connected as the input end of the main loop current mirror for inputting the measured current.

3. A current logarithmic measuring instrument according to claim 1 or 2, characterized in that If the sub-loop current mirror is a shunt mirror, the sub-loop current mirror includes m PNP transistors, m≥2; the bases of all PNP transistors are connected together, and the emitters are connected to VCC; the collector of one of the PNP transistors serves as the output end of the sub-loop current mirror, and the collectors of the remaining PNP transistors are connected as the input end of the sub-loop current mirror, which is used to connect to the output end of the main loop current mirror.

4. A current logarithmic measuring instrument according to claim 1, characterized in that If the sub-loop current mirror is a current doubler mirror, the main loop current mirror includes n NPN transistors, n≥2; the bases of all NPN transistors are connected together, and the emitters are grounded; the collector of one of the NPN transistors serves as the input end of the main loop current mirror, for inputting the measured current, and the collectors of the remaining NPN transistors are connected as the output end of the main loop current mirror.

5. A current logarithmic measuring instrument according to claim 1 or 4, characterized in that If the sub-loop current mirror is a current doubler mirror, the sub-loop current mirror includes m PNP transistors, m≥2; the bases of all PNP transistors are connected together, and the emitters are connected to VCC; the collector of one of the PNP transistors serves as the input end of the sub-loop current mirror, which is used to connect to the output end of the main loop current mirror, and the collectors of the remaining PNP transistors are connected to serve as the output end 2 of the sub-loop current mirror.

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