CN117741493A - High-precision ultra-low ripple test device and test method - Google Patents
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Abstract
The invention discloses a high-precision ultra-low ripple test device and a test method, and relates to the technical field of power supply ripple test. The measuring device mainly comprises an isolation AC-DC unit, an operational amplifier, a feedback circuit and test equipment. The DC component output by the ultra-low ripple power supply is filtered through the isolation AC unit to obtain a power supply ripple AC component to be tested, the ripple AC component is amplified by the operational amplifier and then is connected with the detection probe of the test equipment to be tested, so that the ripple AC component is not interfered by environmental noise, and the power supply ripple is obtained by back-pushing according to the test result of the test equipment and the gain of the operational amplifier, thereby being capable of testing the ultra-low ripple. The testing device has the advantages of simple circuit and low manufacturing cost.
Description
Technical Field
The invention relates to the technical field of power supply ripple test, in particular to a high-precision ultralow ripple test device.
Background
At present, a high-voltage power supply ripple detection method adopts a high-voltage high-precision resistor voltage division mode, a plurality of resistor voltage division exists in resistor voltage division, loss is large, and low frequency is not easy to detect. In some special application fields, such as piezoelectric servo control application, the peak value of the peak of the ripple peak of the piezoelectric ceramic driving power supply is usually required to be less than 5mV, and even lower, especially in the piezoelectric servo control of high-precision equipment such as photoetching equipment, the peak value of the output voltage ripple peak is required to be less than 50uV. In a conventional laboratory environment, the environmental noise of an oscilloscope is usually about 10mV, the environmental noise of the laboratory directly covers the ripple wave of the power supply output, and for a test scene that the ripple wave of the power supply output is less than 1mV, the existing ripple wave test technology cannot test against ultra-low ripple waves.
Disclosure of Invention
The invention provides a high-precision ultra-low ripple test device and a test method, which are used for solving the problem that the existing ripple test technology cannot test ultra-low ripple.
The invention is realized by the following technical scheme:
the invention provides a high-precision ultra-low ripple testing device, which comprises a first isolation AC unit, an operational amplifier, a feedback circuit and testing equipment;
the output end of the first isolation AC unit is connected with the non-inverting input end of the operational amplifier, the input end of the first isolation AC unit is used for being connected with the power supply output of ultra-low ripple, and the output end of the operational amplifier is connected with the detection probe of the test equipment;
the feedback circuit is connected with the inverting input end of the operational amplifier after a first resistor is connected in series with the output end of the operational amplifier, and the first resistor is grounded after a second resistor is connected in series with the first resistor.
The invention relates to a testing device, which mainly comprises an isolated DC-AC unit, an operational amplifier, a feedback circuit and testing equipment, wherein the output of an ultra-low ripple power supply is firstly filtered by the first isolated DC-AC unit, the AC component of the output of the power supply is reserved to obtain the AC component of the power supply ripple to be tested, the feedback circuit provides gain for the operational amplifier, the AC component of the ripple is amplified by the operational amplifier and then is subjected to ripple testing by the testing equipment, so that the AC component of the ripple is not interfered by environmental noise, and the power supply ripple is obtained by reverse thrust according to the testing result of the testing equipment and the gain of the operational amplifier, thereby the testing device can test the ultra-low ripple.
In one embodiment, a second isolation through-crossing unit is connected between the first resistor and the second resistor in series, and a connecting wire of the second isolation through-crossing unit and the second resistor is connected to a non-inverting input end of the operational amplifier after being connected with a third resistor in series.
In one embodiment, the first isolated dc-ac unit is a capacitor.
In one embodiment, the operational amplifier is a high-precision operational amplifier.
In one embodiment, the detection probe of the test device comprises a positive electrode detection probe and a negative electrode detection probe, the output end of the operational amplifier is connected with the positive electrode detection probe of the test device, and the negative electrode detection probe of the test device is grounded.
In one embodiment, the test device is an oscilloscope and the test probe is a low voltage probe.
In one embodiment, the first resistor has a resistance value substantially greater than a resistance value of the second resistor.
In one embodiment, the gain of the operational amplifier is:
wherein R is 1 R is the resistance value of the first resistor 2 And Au is the gain of the operational amplifier for the resistance value of the second resistor.
In one embodiment, the gain of the operational amplifier is 100.
In a second aspect of the present invention, there is provided a high-precision ultra-low ripple measurement method, the measurement method comprising:
the high-precision ultra-low ripple testing device according to any embodiment of the present invention is built, and the resistance values of the first resistor and the second resistor in the measuring device are configured to obtain the gain of the operational amplifier;
connecting the input end of a first isolation AC unit in the testing device with the power supply output of the ultra-low ripple wave for measuring the ultra-low ripple wave;
obtaining the peak-to-peak value of the ultra-low ripple according to the measured value of the test probe in the test device and the gain of the operational amplifier:wherein V is pp (out) is the measurement value of the test probe, au is the gain of the operational amplifier, V pp (in) is the peak-to-peak value of the ultra-low ripple.
Compared with the prior art, the invention has the following advantages and beneficial effects: the test device comprises an isolated DC-DC unit, an operational amplifier, a feedback circuit and test equipment, wherein the output of the ultra-low ripple power supply keeps the AC component of the output through the first isolated DC-DC unit, and then the AC component is amplified by the operational amplifier and then subjected to ripple test, so that the ripple AC component is not interfered by environmental noise, and the test device can test ultra-low ripple.
The second isolation AC unit is connected in series in the feedback loop to play a role of isolation AC, and meanwhile, the input impedance of the AC homodromous amplifying circuit is increased, the gain precision of the amplifying circuit is ensured, and the accuracy of a test result is improved.
The testing device is suitable for the ultra-low ripple testing occasion and has the advantages of simple circuit, low manufacturing cost, high measuring precision and the like. And the peak value of the ripple peak can be obtained rapidly according to the gain of the operational amplifier and the measurement result, the test method is simple, and the test efficiency is high.
Drawings
In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings that are needed in the examples will be briefly described below, it being understood that the following drawings only illustrate some examples of the present invention and therefore should not be considered as limiting the scope, and that other related drawings may be obtained from these drawings without inventive effort for a person skilled in the art. In the drawings:
FIG. 1 is one of the circuit diagrams of a high-precision ultra-low ripple test apparatus according to an embodiment of the present invention;
FIG. 2 is a second circuit diagram of a high-precision ultra-low ripple test device according to an embodiment of the present invention;
FIG. 3 is a simulated circuit diagram of a high-precision ultra-low ripple test device according to an embodiment of the present invention;
FIGS. 4 (a) -4 (c) are graphs of simulated ripple waveforms output by the simulated test device;
fig. 5 is the result of ripple testing of a power supply in an open environment laboratory using the high precision ultra low ripple testing device of the present invention.
Detailed Description
For the purpose of making apparent the objects, technical solutions and advantages of the present invention, the present invention will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present invention and the descriptions thereof are for illustrating the present invention only and are not to be construed as limiting the present invention.
It is noted that the terms "comprising" and "having," and any variations thereof, in the description and claims of the present invention and in the foregoing figures, are intended to cover a non-exclusive inclusion, such as a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to or includes other steps or elements inherent to the apparatus.
The terminology used in the various embodiments of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the various embodiments of the application. As used herein, the singular is intended to include the plural as well, unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which various embodiments of this application belong. The terms (such as those defined in commonly used dictionaries) will be interpreted as having a meaning that is identical to the meaning of the context in the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein in connection with the various embodiments.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: no such specific details are necessary to practice the invention. In other instances, well-known structures, circuits, materials, or methods have not been described in detail in order not to obscure the invention.
The embodiment of the invention provides a high-precision ultra-low ripple test device, which is suitable for ultra-low ripple test occasions and is beneficial to improving the test precision and the test efficiency of ultra-low ripple.
The present invention will be described in detail below with reference to the accompanying drawings, as shown in fig. 1, fig. 1 is one of circuit diagrams of a high-precision ultra-low ripple test device of the present invention, where the test circuit includes a first isolation ac unit C1, an operational amplifier U1, a feedback circuit and a test apparatus;
the output end of the first isolation AC unit C1 is connected with the non-inverting input end of the operational amplifier U1, the input end of the first isolation AC unit C1 is used for being connected with the power output (Vi) of ultra-low ripple, and the output end of the operational amplifier U1 is connected with the detection probe of the test equipment;
the feedback circuit is connected with the inverting input end of the operational amplifier U1 after the output end of the operational amplifier U1 is connected with the first resistor R1 in series,
the first resistor R1 and the series connection second resistor R2 are grounded.
In the testing device, the isolated direct current alternating current unit has the characteristic of isolating direct current from alternating current, the input end of the first isolated direct current unit is connected with the power output of ultra-low ripple waves, the direct current component of the power output is filtered, the alternating current component of the power output is reserved, the alternating current component of the power ripple waves to be tested is obtained, the direct current component is amplified by the operational amplifier and is output to the test point, and therefore the detection probe of the testing equipment is connected with the test point for testing. The operational amplifier is provided with a feedback circuit, the gain ripple alternating current component of the operational amplifier is regulated through a series feedback resistor and amplified by the operational amplifier, so that the ripple alternating current component is not interfered by environmental noise, a common monitoring probe can test the ripple alternating current component, and the power output ripple can be obtained according to the test result of the test equipment and the gain reverse thrust of the operational amplifier, so that the test device can test the ultra-low ripple. In some embodiments of the invention, the accuracy of the gain of the amplifying circuit is ensured by increasing the input impedance of the ac homodromous amplifying circuit by series connection of the cut-off and cut-through unit in the feedback circuit. As shown in fig. 2, fig. 2 is a second circuit diagram of the high-precision ultra-low ripple test device of the present invention, wherein a second isolation through-switch unit C2 is connected in series between a first resistor R1 and a second resistor R2, and a connecting line between the second isolation through-switch unit C2 and the second resistor R2 is connected in series with a third resistor R3 and then connected to a non-inverting input terminal of an operational amplifier.
The second isolation and direct-current alternating-current unit C2 plays a role in isolating and direct-current alternating-current, and meanwhile, the input impedance of the alternating-current homodromous amplifying circuit is increased, and the gain precision of the amplifying circuit is guaranteed, so that the accuracy of a test result is improved.
In some embodiments of the present invention, the first cut-off and pass-through unit C1 and the second cut-off and pass-through unit C2 in the test apparatus are implemented by using capacitors, and the capacitor C1 used as the first cut-off and pass-through unit and the capacitor C2 used as the second cut-through and pass-through unit may be the same capacitor or different capacitors. It will be appreciated that the use of a single capacitor as the cut-through unit is the simplest and least costly means, but is not limited to the use of a single capacitor, and that the first cut-through unit and the second cut-through unit may take other existing forms of cut-through circuit, and that the cut-through circuits used by the first cut-through unit and the second cut-through unit may be the same or different.
In some embodiments of the present invention, the operational amplifier U1 in the test apparatus is a high-precision operational amplifier. Such as OP07, OP27, AD508, LT1195, and chopper-stabilized low drift device ICL7650 composed of MOSFETs. Preferably, the high precision operational amplifier is LT1195.
In some embodiments of the present invention, the test probe of the test device includes a positive electrode test probe and a negative electrode test probe, an output end of the operational amplifier is connected to the positive electrode test probe of the test device, and the negative electrode test probe of the test device is grounded. Therefore, the measurement of the test point through the monitoring probe is realized, wherein the test is the output end of the operational amplifier. In this embodiment, the test apparatus may not be included in the test device of the present invention, but may be provided separately from the test device, which has the advantage that the test apparatus or the test probe may be replaced at any time as required.
In some embodiments of the present invention, the test apparatus is an oscilloscope, and the test probe is a low-voltage probe.
In some embodiments of the invention, the resistance value of the first resistor is substantially greater than the resistance value of the second resistor.
The testing device of the invention can adjust the gain of the operational amplifier through the resistance values of the first resistor and the second resistor, and in particular, the gain Au of the operational amplifier can be expressed as
Wherein v is 0 To detect the output of the probe, v i R is the ultra-low ripple voltage output 1 A resistance value of the first resistor R 2 The resistance value of the second resistor.
If the low-voltage probe measures output v 0 Peak value of the peak of the wave is V pp (out), then the ultra-low ripple power supply output v i Peak value of the peak of the wave is V pp (in) then there areDue to ultra-low ripple power supply output v i Very small, usually less than 1mV, in a conventional laboratory environment, the environmental noise of an oscilloscope is usually about 10mV, and the environmental noise of the laboratory directly covers the ripple of the power supply output, so that the ultra-low ripple cannot be tested. In the measuring device, the gains of the operational amplifier are increased by adjusting the resistance values of the first resistor and the second resistor, so that the output voltage of the test point meets the measuring range of the measuring test equipment.
In one embodiment, the gain of the operational amplifier is:
wherein R is 1 A resistance value of the first resistor R 2 And Au is the gain of the operational amplifier, and the resistance value of the second resistor is the gain of the operational amplifier.
In one embodiment, the gain of the operational amplifier is 100. The resistance value of the first resistor in the measuring device is set to 99kΩ, the resistance value of the second resistor is set to 1kΩ, and the gain of the operational amplifier is configured to be 100. According to the formulaMeasurement result V with test probe pp (out) dividing by the gain of the op amp to obtain a measure of the ultra-low ripple. It can be seen that setting the gain of the operational amplifier to 100 is convenient for setting the resistance value and calculating the measurement value of the ultra-low ripple according to the measurement result.
In a second aspect of the present invention, there is provided a high-precision ultra-low ripple test method, the measurement method comprising:
building the high-precision ultra-low ripple testing device in any one of the embodiments, and configuring the resistance values of a first resistor and a second resistor in the measuring device to obtain the gain of an operational amplifier;
connecting the input end of a first isolation AC unit in the testing device with the power supply output of the ultra-low ripple wave for measuring the ultra-low ripple wave; based on measurements and movement of test probes in a test apparatusCalculating the gain of the amplifier to obtain the peak-to-peak value of the ultra-low ripple wave:wherein V is pp (out) is the measurement value of the test probe, au is the gain of the operational amplifier, V pp (in) is the peak-to-peak value of the ultra-low ripple.
As shown in fig. 3, fig. 3 is a simulation circuit diagram of the ultra-low ripple test apparatus. The high-precision ultra-low ripple testing device in the embodiment of the invention is simulated, and the testing device is verified through simulation results. The peak value of the peak of the input alternating current ripple is set to be 1mV, the resistance value of the first resistor is set to be 99KΩ, the resistance value of the second resistor is set to be 1KΩ, the operational amplifier adopts a low-power-consumption high-precision operational amplifier LT1195, and the gain is 100.
As shown in fig. 4 (a) -4 (c), fig. 4 (a) -4 (c) show simulated waveforms of ripple waves outputted from the simulation test device, curve (vi) in fig. 4 (a) shows an ultra-low ripple power supply output voltage, the dc component is set to be 5V, and the peak-peak value of the ac component ripple wave is set to be V PP (in) = 5.0005V-4.9995 v=0.001 v=1ma, the frequency is 100kHz, the curve (p_opa) in fig. 4 (b) is the signal of the co-directional input end of the operational amplifier, the signal is the ac component of the power output voltage after the dc blocking and crossing of the capacitor C1, and the peak-to-peak value is V p_opa (in) = -0.058914V- (-0.059905V) = 0.000991 v=0.991 mV, curve (vo) in fig. 4 (c) is the output signal of the operational amplifier, with peak-to-peak value V PP (out) = 0.033245V- (-0.06366V) = 0.096905 v= 96.905mV. Because the selected operational amplifier (LT 1195) is not an ideal operational amplifier, the factors such as bias current, offset current and the like exist at the same-direction input end and the opposite-direction input end, so that the simulation result is not an ideal 100mV output, the simulation output error rate is delta= (100 mV-96.905 mV)/100 mV= 3.095%, and the simulation output error rate meets the condition of an actual test circuit.
As shown in fig. 5, fig. 5 is a result of ripple testing of a certain power supply in an open environment laboratory using the high-precision ultra-low ripple testing device of the present invention. The peak value of the peak of the input alternating current ripple is set to be 1mV, the resistance value of the first resistor is set to be 99KΩ, the resistance value of the second resistor is set to be 1KΩ, the operational amplifier adopts a low-power-consumption high-precision operational amplifier LT1195, and the gain is 100.
And testing the output end by adopting an oscilloscope low-voltage probe, wherein the peak value of the output ripple peak is 49.6mV, and then the peak value of the ripple peak of the input end power supply is 49.6 mV/100=0.496 mV.
Through circuit simulation and actual power supply ripple test, the feasibility of the high-precision ultra-low ripple test device is verified, and the device is particularly suitable for test requirement scenes of ultra-low ripple (less than 1 mV). The high-precision ultra-low ripple testing device has the following advantages:
1. the ultra-low ripple power output firstly passes through the first isolation AC unit, the DC component of the power output is filtered, the AC component is reserved, namely the power ripple AC component to be tested is amplified by the operational amplifier, and the ultra-low ripple is tested by the testing equipment.
2. The second isolation AC unit is connected in series in the feedback loop to play a role of isolation AC, and meanwhile, the input impedance of the AC homodromous amplifying circuit is increased, so that the gain precision of the amplifying circuit is ensured.
3. The gain of the operational amplifier is configured by setting the first resistor and the second resistor, so that the gain of the operational amplifier is adjustable, and the operational amplifier is applicable to different test scenes.
4. The testing device has the advantages of simple structure, low cost, simple testing process and high measuring precision.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the invention, and is not meant to limit the scope of the invention, but to limit the invention to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (10)
1. The high-precision ultra-low ripple testing device is characterized by comprising a first isolation AC unit, an operational amplifier, a feedback circuit and testing equipment;
the output end of the first isolation AC unit is connected with the non-inverting input end of the operational amplifier, the input end of the first isolation AC unit is used for being connected with the power supply output of ultra-low ripple, and the output end of the operational amplifier is connected with the detection probe of the test equipment;
the feedback circuit is connected with the inverting input end of the operational amplifier after a first resistor is connected in series with the output end of the operational amplifier, and the first resistor is grounded after a second resistor is connected in series with the first resistor.
2. The high-precision ultra-low ripple test device of claim 1, wherein a second isolation through-crossing unit is connected in series between the first resistor and the second resistor, and a connecting wire of the second isolation through-crossing unit and the second resistor is connected in series with a third resistor and then connected to a non-inverting input end of the operational amplifier.
3. The high precision ultra-low ripple test device of claim 1, wherein the first isolated ac unit is a capacitor.
4. The high-precision ultra-low ripple test device of claim 1, wherein the operational amplifier is a high-precision operational amplifier.
5. The high-precision ultra-low ripple test device of claim 1, wherein the test probe of the test equipment comprises a positive electrode test probe and a negative electrode test probe, the positive electrode test probe of the test equipment is connected with the output end of the operational amplifier, and the negative electrode test probe of the test equipment is grounded.
6. The high-precision ultra-low ripple test device of claim 5, wherein the test equipment is an oscilloscope and the test probe is a low-voltage probe.
7. The high-precision ultra-low ripple test device of claim 1, wherein the resistance value of the first resistor is substantially greater than the resistance value of the second resistor.
8. The high-precision ultra-low ripple test device of claim 1, wherein the gain of the operational amplifier is:
wherein R is 1 R is the resistance value of the first resistor 2 And Au is the gain of the operational amplifier for the resistance value of the second resistor.
9. The high-precision ultra-low ripple test device of claim 1, wherein the gain of the operational amplifier is 100.
10. The high-precision ultra-low ripple test method is characterized by comprising the following steps of:
building the high-precision ultra-low ripple testing device according to any one of claims 1-9, and configuring the resistance values of a first resistor and a second resistor in the testing device to obtain the gain of an operational amplifier;
connecting the input end of a first isolation AC unit in the testing device with the power supply output of the ultra-low ripple wave for measuring the ultra-low ripple wave;
obtaining the peak-to-peak value of the ultra-low ripple according to the measured value of the test probe in the test device and the gain of the operational amplifier:wherein V is pp (out) is the measurement value of the test probe, au is the gain of the operational amplifier, V pp (in) is the peak-to-peak value of the ultra-low ripple.
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