CN114578112A - Attenuation temperature drift method for digital oscilloscope and digital oscilloscope - Google Patents
Attenuation temperature drift method for digital oscilloscope and digital oscilloscope Download PDFInfo
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Abstract
The application discloses an attenuation temperature drift method for a digital oscilloscope and the digital oscilloscope. Firstly, acquiring a vertical gear setting value of a digital oscilloscope; and then, attenuating or amplifying the bias voltage signal output by the bias adjusting circuit according to the vertical gear setting value, and outputting the attenuated or amplified bias voltage signal to the impedance transformation network so that the attenuated or amplified bias voltage signal is superposed with the output signal of the attenuation network by the impedance transformation network, thereby attenuating the temperature drift phenomenon when the digital oscilloscope displays the waveform. Because the bias voltage signal is adjusted according to the vertical gear setting value, the attenuation of the temperature drift phenomenon is realized, and the waveform display effect of the digital oscilloscope is further enhanced, so that the user experience is improved.
Description
Technical Field
The invention relates to the technical field of oscilloscopes, in particular to an attenuation temperature drift method for a digital oscilloscope and the digital oscilloscope.
Background
The digital oscilloscope is an indispensable tool for designing, manufacturing and maintaining electronic equipment, the digital oscilloscope is mainly used at present, the digital oscilloscope is increasingly popularized due to functions of waveform triggering, storing, displaying, measuring, analyzing and the like, and the digital oscilloscope is considered as eyes of engineers as the scientific and market demands are rapidly developed, and the digital oscilloscope is used as a necessary tool for meeting measurement challenges of the engineers. Particularly, in the development process of electronic circuits, an oscilloscope is required to be frequently used for debugging and measuring, the measurement precision is higher and higher, and the performance requirement on the oscilloscope is higher and higher. The prior oscilloscope realizes the sampling, mapping and displaying of signal data through a memory, a Central Processing Unit (CPU), a programmable logic device and an external device thereof, and comprises a sampling module, a data preprocessing module, an acquisition control module, a data processing unit, a data mapping unit, a waveform graph generating unit and a display screen; the sampling module samples signal data, the sampled data is input into the data preprocessing module to perform delay adjustment between analog signal data and digital signal data, the signal data is acquired and stored through the acquisition control module, the data processing unit processes the acquired signal data of each channel, the processed data signals are mapped into two-dimensional waveform data by the data mapping unit and stored into the external memory (QDR), the data in the external memory (QDR) is converted into RGB graphic data by the color conversion unit, then the waveform data and data such as screen grids and menus generated by the CPU are merged by the display unit, and finally the data are displayed on the display screen. The parameters of a front-end analog device of the oscilloscope are easily influenced by temperature, the small-voltage gear display waveform drift is shown on the oscilloscope, when the temperature around the analog device changes, the small-voltage display drift phenomenon is more obvious, the measurement precision of small signals is reduced, and further the user test is influenced. And the degree of waveform drift is shown to be related to the individual analog devices, and finally, different waveform drifts of different machines are shown. Therefore, it is necessary to design a method for generating the temperature drift phenomenon when the displayed waveform of the digital oscilloscope is attenuated.
Disclosure of Invention
The invention mainly solves the technical problems that: the technical problem of how to attenuate the temperature drift phenomenon of the display waveform of the oscilloscope caused by the temperature change is solved.
According to a first aspect, the present application provides a digital oscilloscope, comprising a controller, an attenuation network, an impedance transformation network, a first adjustable gain amplifier, an analog-to-digital converter, a bias adjusting circuit, a bias gain circuit, a digital-to-analog converter and a display;
the attenuation network is connected with the impedance transformation network and is used for attenuating an input signal input into the digital oscilloscope to obtain a first adjusting signal and outputting the first adjusting signal to the impedance transformation network;
the digital-to-analog converter is respectively connected with the controller and the offset adjusting circuit, and is used for converting offset codes of a digital signal output by the controller into offset code signals of analog signals and sending the offset code signals to the offset adjusting circuit;
the bias adjusting circuit is connected with the bias gain circuit and used for generating a first analog bias voltage signal according to the bias coding signal and sending the first analog bias voltage signal to the bias gain circuit;
the bias gain circuit is connected with the impedance transformation network and is used for attenuating or amplifying the first analog bias voltage signal according to gear setting parameters to obtain a second analog bias voltage signal and sending the second analog bias voltage signal to the impedance transformation network;
the impedance transformation network is connected with the first adjustable gain amplifier and used for acquiring a superposed signal according to the first adjusting signal and the second analog bias voltage signal and sending the superposed signal to the first adjustable gain amplifier;
the first adjustable gain amplifier is respectively connected with the controller and the analog-to-digital converter, and is used for amplifying or attenuating the superposed signal according to the configuration gain parameter output by the controller to obtain a second adjusting signal and sending the second adjusting signal to the analog-to-digital converter;
the analog-to-digital converter is connected with the controller and is used for converting the second adjusting signal into a digital waveform signal and sending the digital waveform signal to the controller;
the controller is respectively connected with the display, the bias gain circuit and the digital-to-analog converter; the controller is used for sending the gear setting parameter to the bias gain circuit according to the current vertical gear setting value of the digital oscilloscope; the controller is further configured to send a preset offset adjustment parameter to the digital-to-analog converter, so that the digital-to-analog converter converts the offset adjustment parameter into the offset encoding signal of the analog signal; the controller is further configured to obtain a first display driving signal according to the digital waveform signal, and send the first display driving signal to the display, so that the display displays the first waveform signal according to the first display driving signal.
In one embodiment, the controller is configured to send the gear setting parameter to the bias gain circuit according to a current vertical gear setting value of the digital oscilloscope, and includes:
when the vertical gear setting value of the digital oscilloscope is not greater than a first gear value, the gear setting parameter output to the bias gain circuit by the controller is a low gear parameter;
under the condition of the low gear parameter, the bias gain circuit attenuates the first analog bias voltage signal according to the low gear parameter to obtain a second analog bias voltage signal; wherein the attenuation multiple is greater than 1.
In one embodiment, the controller is configured to send the gear setting parameter to the bias gain circuit according to a current vertical gear setting value of the digital oscilloscope, and includes:
when the vertical gear setting value of the digital oscilloscope is larger than a first gear value, the gear setting parameter output to the bias gain circuit by the controller is a high gear parameter;
under the condition of the high gear parameter, the bias gain circuit amplifies the first analog bias voltage signal according to the high gear parameter to obtain a second analog bias voltage signal; wherein the magnification is not less than 1.
In one embodiment, the attenuation multiple or the amplification multiple of the first analog bias voltage signal by the bias gain circuit is obtained according to the attenuation multiple of the attenuation network; each attenuation multiple of the attenuation network corresponds to an attenuation multiple of the first analog bias voltage signal, and each attenuation multiple of the attenuation network corresponds to an amplification multiple of the first analog bias voltage signal.
According to a second aspect, the present application provides a decaying temperature drift method for a digital oscilloscope, the digital oscilloscope comprising an impedance transformation network, a bias adjustment circuit and a decaying network, the decaying temperature drift method comprising:
acquiring a vertical gear setting value of the digital oscilloscope;
and attenuating or amplifying a bias voltage signal output by a bias adjusting circuit of the digital oscilloscope according to the vertical gear setting value, and outputting the attenuated or amplified bias voltage signal to an impedance transformation network of the digital oscilloscope, so that the attenuated or amplified bias voltage signal is superposed with an output signal of the attenuation network of the digital oscilloscope by the impedance transformation network, and the temperature drift phenomenon of a displayed waveform of the digital oscilloscope is attenuated.
In an embodiment, the attenuating or amplifying the bias voltage signal output by the bias adjusting circuit of the digital oscilloscope according to the vertical gear setting value includes:
when the vertical gear setting value of the digital oscilloscope is not greater than the first gear value, attenuating a bias voltage signal output by a bias adjusting circuit of the digital oscilloscope; wherein the attenuation multiple is greater than 1.
In an embodiment, the attenuating or amplifying the bias voltage signal output by the bias adjusting circuit of the digital oscilloscope according to the vertical gear setting value includes:
amplifying a bias voltage signal output by a bias adjusting circuit of the digital oscilloscope when the vertical gear setting value of the digital oscilloscope is larger than a first gear value; wherein the magnification is not less than 1.
In one embodiment, the first shift value is NmV, and N is a positive number not greater than 5.
In one embodiment, the method for attenuating temperature drift further comprises:
obtaining the attenuation times or amplification times of the bias voltage signals according to the attenuation times of the attenuation network; each attenuation multiple of the attenuation network corresponds to an attenuation multiple of the bias voltage signal;
each attenuation multiple of the attenuation network corresponds to an amplification multiple of the bias voltage signal.
According to a third aspect, the present application provides a computer-readable storage medium, characterized in that the medium has a program stored thereon, the program being executable by a processor to implement the method of decaying temperature drift according to the second aspect.
According to the attenuation temperature drift method for the digital oscilloscope, the bias voltage signal is adjusted according to the vertical gear setting value, so that the temperature drift phenomenon is attenuated, the waveform display effect of the digital oscilloscope is further enhanced, and the user experience is improved.
Drawings
FIG. 1 is a schematic diagram of a digital oscilloscope;
FIG. 2 is a schematic diagram showing a waveform showing no temperature drift when the digital oscilloscope has no input signal;
FIG. 3 is a schematic diagram of a waveform showing a temperature drift of the waveform when the digital oscilloscope has no input signal;
FIG. 4 is a schematic diagram of a digital oscilloscope in one embodiment;
FIG. 5 is a schematic diagram of a digital oscilloscope in another embodiment;
FIG. 6 is a flow chart of an attenuating temperature drift method for a digital oscilloscope in another embodiment.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, one skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the description of the methods may be transposed or transposed in order, as will be apparent to a person skilled in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings).
Referring to fig. 1, a schematic structural diagram of a digital oscilloscope is shown, where the digital oscilloscope 1 includes an attenuation network 11, a first adjustable gain amplifier 12, an analog-to-digital converter 13, a controller 14, a display 15, a digital-to-analog converter 16, a bias adjustment circuit 17, and an impedance transformation network 18. The attenuation network 11 is configured to perform attenuation adjustment on a signal to be processed input to the digital oscilloscope 1 to adjust the size of the signal in the circuit, and finally output a first adjustment signal. The input signal can here be an analog signal, and the output first control signal is then likewise an analog signal. The attenuation network 11 may have one-time attenuation, ten-time attenuation, and several tens of times attenuation to one hundred times attenuation, which is not limited herein. Since the attenuation network 11 is a common analog signal processing device in a digital oscilloscope, and belongs to the prior art, it is not described here again. First adjustable gain amplifier 12 is configured to amplify and adjust the first adjustment signal to output a second adjustment signal. The first adjustable gain amplifier 12 is also called Variable Gain Amplifier (VGA), and its main function is to adjust the amplification factor of the signal, for example, for the first adjusting signal with voltage of 1mV, if the gain of the adjustable gain amplifier is 1000, the voltage of the output second adjusting signal is 1V. The first adjustable gain amplifier 12 plays a fine tuning role, and the amplification factor thereof may be several times, several tens of times, several hundreds of times, several thousands of times, and is not limited herein. Since the first adjustable gain amplifier 12 is an analog signal processing device commonly used in digital oscilloscopes, and belongs to the prior art, the description thereof is omitted here. The analog-to-digital converter 13 is also called ADC, and is configured to perform analog-to-digital conversion on the second adjustment signal to output digital waveform data of the signal. Since the analog-to-digital converter 13 is a common analog signal processing device in a digital oscilloscope, and belongs to the prior art, it is not described here again. The controller 14 is connected to the analog-to-digital converter 13, and the controller 14 includes a waveform processing unit 141 and a central processing unit 142, and the waveform processing unit 141 is configured to perform precision adjustment on the digital waveform signal and obtain a first waveform according to the precision adjustment. The display 15 is connected to the controller 14 for displaying the first waveform. The central processing unit 142 may be an arithmetic processing device such as a CPU, the central processing unit 142 is connected to the offset adjusting circuit 17 through the analog-to-digital converter 16, the central processing unit 142 sequentially sets a first configuration value corresponding to each line of display pixels in the waveform of the signal, and changes the offset coding corresponding to the plurality of lines of display pixels in the waveform of the signal using the plurality of first configuration values. The central processing unit 142 is further configured to, when it is determined that the currently set first configuration value causes the configuration code to change, send the changed offset code to the offset adjusting circuit 17 through the digital-to-analog converter 16, so that the offset adjusting circuit 17 performs offset display adjustment on the corresponding rows of display pixels according to the changed offset code, and reset the second configuration value. The front-end circuits of the oscilloscope are all analog signals, and the digital-to-analog converter 16 is used for converting digital signal offset codes into analog signals and outputting the analog signals to the offset adjusting circuit 17. The bias adjustment circuit 17 is operable to generate a plurality of analog bias voltage signals in response to a first configuration value. Since the bias adjusting circuit 17 is a commonly used digital signal processing device in a digital oscilloscope, and belongs to the prior art, it is not described here again. The impedance transformation network 18 is connected to the attenuation network 11, the first adjustable gain amplifier 12 and the bias adjusting circuit 17, and is configured to superimpose the first adjusting signal output by the attenuation network with a plurality of analog bias voltage signals generated by the bias adjusting circuit 17 to form a new first adjusting signal, and input the new first adjusting signal to the first adjustable gain amplifier 12, so that the first adjustable gain amplifier 12 amplifies and adjusts the new first adjusting signal to form a new second adjusting signal, and the analog-to-digital converter 13 also outputs new digital waveform data of the signal after performing analog-to-digital conversion on the new second adjusting signal. The waveform processing unit 141 may be a programmable logic processing device such as an FPGA. The central processing unit 142 is further connected to the first adjustable gain amplifier 12 for configuring the gain of the first adjustable gain amplifier 12. The central processing unit 142 is further configured to generate a configuration menu of the waveform of the signal (the configuration menu may include items such as a status bar and a network), and send the configuration menu to the waveform processing unit 141, so that the waveform processing unit 141 displays and superimposes the configuration menu and the waveform of the signal, thereby obtaining display superimposed data. The central processing unit 142 is then also used to send the display overlay data to the display for display.
Referring to fig. 2 and fig. 3, they are schematic diagrams of waveforms showing that temperature drift does not occur and temperature drift occurs when the oscilloscope has no input signal, respectively, and the analog front end of the oscilloscope is mostly composed of analog devices, and parameters of the analog devices are easily affected by temperature. The display waveform of the small voltage is changed when the temperature around the analog device is changed, and the phenomenon affects the test of a user. The analog devices that cause drift in the displayed waveform mainly include a digital-to-analog converter and an OFFSET adjustment circuit that provide a dc OFFSET to the input signal, referred to as "OFFSET" in an oscilloscope. The temperature drift is mainly caused by the digital-to-analog converter. Because of the temperature drift, even after calibration, when the temperature changes, the zero flat line can deviate from the zero point under the condition that no signal is input in a small voltage gear. Based on the analysis of the reason for the temperature drift of the displayed waveform, a temperature drift compensation method for a digital oscilloscope is disclosed in patent document with the invention name of 'temperature drift compensation method, circuit and digital oscilloscope' of patent application number 202110445185.7, the temperature of the digital oscilloscope is monitored by adding a temperature sensor, and a temperature drift offset conditioning electric signal is output according to the temperature value obtained by monitoring and sent to a bias adjusting circuit, so that the temperature drift compensation of the displayed waveform of the digital oscilloscope is realized. The method can improve the temperature drift in the environment with slow temperature change, but when the temperature changes sharply, the temperature measured by the temperature sensor and the actual temperature of the offset circuit are lagged, so that the overcompensation can be caused. Furthermore, constant temperature monitoring and offset compensation can also increase the computational burden on the system.
Referring to fig. 4, which is a schematic structural diagram of an embodiment of a digital oscilloscope, the range of the analog bias voltage signal output by the bias adjusting circuit 17 is between-5V and 5V. The attenuation network 11 includes a first passive attenuation module 111 and a second passive attenuation module 112, both the first passive attenuation module 111 and the second passive attenuation module 112 are passive attenuation modules of 10 times, and the input signal VIN may be attenuated by 10 times by the attenuation network 11 or directly pass through (without attenuation). There are 3 signal magnitudes arriving at impedance transformation network 18, VIN/10, and VIN/100, respectively. The impedance transforming network 18 is equivalent to an adder, and adds the input signal VIN passing through the attenuation network 11 and the analog bias voltage signal output by the bias adjusting circuit 17, and outputs the added signal to the first adjustable gain amplifier 12. Then, simulating the relationship between the offset voltage signal and the offset of the input signal VIN, i.e. the offset range is:
when the input signal VIN is not attenuated (straight-through), the range of the offset seen from the input port is (-5V, 5V);
when the input signal VIN is attenuated by 10 times, the offset range looking into the input port is (-50V, 50V);
when the input signal VIN is attenuated by 100 times, the offset range looking into the input port is (-500V, 500V).
The gears of the digital oscilloscope are generally 1mV,2mV, 5mV … 10V and the like, the gears are firstly divided into a plurality of coarse ranges through the attenuation network 11, for example, signals input by the gears from 1mV to 100mV are relatively small, and the signals can be directly sent to the impedance transformation network 18 without passive attenuation. The gear is attenuated by a factor of 10 when the gear is a little larger, and the maximum gear is attenuated by a factor of 100 when the gear is a little larger. Within the same coarse range, the first adjustable gain amplifier 12 and the digital gain are used to divide the finer steps. According to the analysis of the adjustable offset range, if the voltages output by the offset adjusting circuit 17 are the same, the offset ranges are the same in the gear of the same passive attenuation range. In the above example, the range of shift offsets of 1mV and 100mV are both (-5V, 5V). In practice, however, small gears do not have as large an offset voltage range. For example, a voltage shift of ± 5V can be performed in a 1mV gear, which is not significant in practical application, but rather deteriorates the temperature drift performance of a small gear.
Based on the above analysis on the adjustable offset range, the digital oscilloscope disclosed in the embodiment of the present application adds an adjustable offset gain circuit between the offset adjusting circuit and the impedance transformation network. Therefore, when the same passive attenuation gear is used by the attenuation network, the bias adjusting circuit can output different bias voltage ranges according to the actual application condition. When the attenuation network is set to be a small gear, the bias voltage signal output by the bias adjusting circuit is attenuated, so that the temperature drift phenomenon can be attenuated simultaneously, the temperature drift problem of the attenuation network set to be a small gear is further improved, the displayed waveform temperature drift phenomenon of the digital oscilloscope caused by temperature change is weakened, the visual effect of waveform display is enhanced, and the observation experience of a user is improved.
The technical solution of the present application will be specifically described with reference to the following examples.
Example one
Referring to fig. 5, which is a schematic structural diagram of another embodiment of a digital oscilloscope, the digital oscilloscope 1 includes a controller 14, an attenuation network 11, an impedance transformation network 18, a first adjustable gain amplifier 12, an analog-to-digital converter 13, a bias adjusting circuit 17, a bias gain circuit 19, a digital-to-analog converter 16, and a display 15. Attenuation network 11 is connected to impedance transformation network 18, and attenuation network 11 is configured to attenuate input signal VIN of input digital oscilloscope 1 to obtain first adjustment signal VIN1, and output first adjustment signal VIN1 to impedance transformation network 18. The digital-to-analog converter 16 is respectively connected to the controller 14 and the offset adjusting circuit 17, and the digital-to-analog converter 16 is configured to convert an offset code of a digital signal output by the controller 14 into an offset code signal VDAC of an analog signal and send the offset code signal VDAC to the offset adjusting circuit 17. The offset adjusting circuit 17 is connected to the offset gain circuit 19, and the offset adjusting circuit 17 is used for generating a first analog offset voltage Voffset1 according to the offset encoding signal VDAC and sending the first analog offset voltage Voffset1 to the offset gain circuit 19. The offset gain circuit 19 is connected to the impedance transforming network 18, and the offset gain circuit 19 is configured to attenuate or amplify the first analog offset voltage Voffset1 according to the gear setting parameter to obtain a second analog offset voltage Voffset2, and send the second analog offset voltage Voffset2 to the impedance transforming network 18. The impedance transforming network 18 is connected to the first adjustable gain amplifier 12, and the impedance transforming network 18 is configured to obtain the superimposed signal VIN2 according to the first adjusting signal VIN1 and the second analog offset voltage signal Voffset2, and send the superimposed signal VIN2 to the first adjustable gain amplifier 12. The first adjustable gain amplifier 12 is connected to the controller 14 and the analog-to-digital converter 13, respectively, and the first adjustable gain amplifier 12 is configured to amplify or attenuate the superimposed signal VIN2 according to a configured gain parameter output by the controller 14 to obtain a second adjustment signal, and send the second adjustment signal to the analog-to-digital converter 13. The analog-to-digital converter 13 is connected to the controller 14, and the analog-to-digital converter 13 is configured to convert the second adjustment signal into a digital waveform signal and send the digital waveform signal to the controller 14. The controller 14 is connected to the display 15, the bias gain circuit 19 and the digital-to-analog converter 16, respectively. The controller 14 is configured to output the gear setting parameter to the offset gain circuit 19 according to the vertical gear setting value of the digital oscilloscope 1. The controller 14 is further configured to send a preset offset adjustment parameter to the dac 16, so that the dac 16 converts the offset adjustment parameter into an offset encoding signal VDAC of an analog signal. The controller 14 is further configured to obtain a first display driving signal according to the digital waveform signal, and send the first display driving signal to the display 15, so that the display 15 displays the first waveform signal according to the first display driving signal. The offset adjustment parameter output by the controller 14 is used to adjust the first waveform signal, and each vertical gear setting value corresponds to one gear setting parameter.
In one embodiment, when the vertical gear setting value of the digital oscilloscope 1 is not greater than the first gear value, the gear setting parameter output by the controller 14 to the offset gain circuit 19 is a low gear parameter, and under the condition of the low gear parameter, the offset gain circuit 19 attenuates the first analog offset voltage signal Voffset1 according to the low gear parameter to obtain a second analog offset voltage signal Voffset2, wherein the attenuation multiple is greater than 1; when the vertical gear setting value of the digital oscilloscope 1 is greater than the first gear value, the gear setting parameter output by the controller 14 to the offset gain circuit 19 is a high gear parameter, and under the condition of the high gear parameter, the offset gain circuit 19 amplifies the first analog offset voltage signal Voffset1 according to the high gear parameter to obtain a second analog offset voltage signal Voffset2, wherein the amplification factor is not less than 1. In one embodiment, the first shift value is NmV, and N is a positive number less than 5.
The attenuation factor or amplification factor of the offset gain circuit 19 for the first analog offset voltage signal Voffset1 is obtained according to the attenuation factor of the attenuation network 11. Each attenuation factor of the attenuation network 11 corresponds to an attenuation factor of the first analog offset voltage signal Voffset1, and each attenuation factor of the attenuation network 11 corresponds to an amplification factor of the first analog offset voltage signal Voffset 1.
In the embodiment of the present application, as shown in fig. 5, a signal of the input signal VIN passing through the attenuation network 11 is the first adjustment signal VIN 1. The offset coding signal VDAC output by the dac 16, because the dac 16 can only output forward voltage, needs the offset adjusting circuit 17 to convert the forward voltage into the first analog offset voltage Voffset1 of positive and negative voltage, and then outputs the second analog offset voltage Voffset2 after being amplified or attenuated by the offset gain circuit, so that:
Voffset2= Voffset1*G3；
where G3 is the amplification or attenuation factor of the bias gain circuit 19.
Because the impedance transformation network 18 behaves as an adder,:
VIN2=VIN*G1+ Voffset1*G3； （1）
after transformation, the following results are obtained:
VIN=(VIN2-Voffset1*G3)/G1； （2）
the superimposed signal VIN2 is calculated according to a codeword obtained by the analog-to-digital converter 13, the first analog bias voltage signal Vosffset1 is calculated according to a control codeword of the digital-to-analog converter 16, G1 is a multiple of amplification and attenuation of the attenuation network 11 and can be obtained by calibration, G3 is a known quantity, and the magnitude of the input signal VIN can be calculated according to the formula (2). The amplification or attenuation factor G3 of the bias gain circuit 19 is controlled by the controller 14, the amplification factor may not be less than 1, and the attenuation factor may be greater than 1.
When the low range parameter is used, the controller 14 controls the gain of G3 to be less than 1, which reduces the temperature drift of the low range. The following formula illustrates how to reduce the temperature drift.
According to the existing knowledge, a small gear temperature drift (for example, 1 mV) is mainly superimposed on the first analog offset voltage signal Voffset1 (refer to CN202110445185.7 temperature drift compensation method, circuit and digital oscilloscope for digital oscilloscope), and the temperature drift sources include a reference voltage temperature drift of an analog-to-digital converter, an output voltage temperature drift, a temperature drift of an amplifier and a resistor of a conditioning circuit, and the like. Assuming that the superimposed temperature drift voltage of the first analog offset voltage Voffset1 is Δ VT1, the superimposed temperature drift is calculated to the input voltage formula as:
VINT=(VIN2-(Voffset1+△VT1)*G3)/G1； （3）
the temperature drift Δ VT reflected to the input terminal can be obtained according to the formula (3) and the formula (2):
△VT=-(△VT1*G3)/G1； （4）
the offset range is Voffset 1G 3/G1; (5)
let G3= 1; the temperature drift before modification, which is present at the input, is then:
△VT =-△VT1/G1；
after improvement, according to the formula (4), in the low gear, the temperature drift of the input terminal can be reduced by setting the gain G3 of the bias gain circuit 19 to be less than 1. The offset range would be G3 times as large as before the improvement, but would still be sufficient in the small gear. In a large gear where the temperature drift is not much affected, the gain G3 of the bias gain circuit 19 is set to a large value.
In one embodiment, the attenuation factor or amplification factor G3 of the first analog bias voltage signal is obtained according to the attenuation factor G1 of the attenuation network, and each attenuation factor G1 of the attenuation network 11 corresponds to an attenuation factor G3 of the bias voltage signal. In one embodiment, each attenuation factor G1 of the attenuation network 11 corresponds to an amplification factor G3 of the temperature-drift bias voltage signal. The calibration of the offset voltage signal is involved, i.e. the corresponding relation between the codeword of the digital-to-analog converter 16 and the offset voltage embodied at the input of the attenuator network 11 needs to be calibrated. The offset voltage range before modification is Voffset1/G1, where G1 is the gain of the attenuator network. A corresponding calibration is performed based on the amount of gain G1. For example, G1 has gains of 1 and 0.1, and it is necessary to calibrate one set of parameters at a gain of 1 and one set of parameters at a gain of 0.1. The offset voltage range after the improvement is Voffset1 × G3/G1, so it needs to calibrate a plurality of parameters. The calibration was performed according to different combinations of (G1, G3).
The digital oscilloscope disclosed in the embodiment comprises a controller, an attenuation network, an impedance transformation network, a first adjustable gain amplifier, an analog-to-digital converter, a bias adjusting circuit, a bias gain circuit, a digital-to-analog converter and a display. Due to the fact that the adjustable bias gain circuit is added between the bias adjusting circuit and the impedance transformation network. Therefore, when the attenuation network uses the same passive attenuation gear, the bias regulating circuit can output different bias voltage ranges according to the practical application condition. When the attenuation network is set to be a small gear, the bias voltage signal output by the bias adjusting circuit is attenuated, so that the temperature drift phenomenon can be attenuated simultaneously, the temperature drift problem of the attenuation network set to be a small gear is further improved, the displayed waveform temperature drift phenomenon of the digital oscilloscope caused by temperature change is weakened, the visual effect of waveform display is enhanced, and the observation experience of a user is improved.
Example two
Referring to fig. 6, a schematic flow chart of an attenuation temperature drift method for a digital oscilloscope in another embodiment is shown, where the digital oscilloscope includes an impedance transformation network, a bias adjustment circuit, and an attenuation network, and the attenuation temperature drift method includes:
and attenuating or amplifying the bias voltage signal output by the bias adjusting circuit of the digital oscilloscope according to the vertical gear setting value, and outputting the attenuated or amplified bias voltage signal to the impedance transformation network so that the impedance transformation network superposes the attenuated or amplified bias voltage signal and the output signal of the attenuation network of the digital oscilloscope, thereby attenuating the temperature drift phenomenon of the displayed waveform of the digital oscilloscope. When the vertical gear setting value of the digital oscilloscope is not larger than the first gear value, the bias voltage signal output by the bias adjusting circuit is attenuated, and the attenuation multiple is larger than 1. And when the vertical gear setting value of the digital oscilloscope is greater than the first gear value, amplifying the bias voltage signal output by the bias adjusting circuit, wherein the amplification factor is not less than 1. In one embodiment, the first shift value is NmV, and N is a positive number not greater than 5.
In one embodiment, the method for attenuating temperature drift further comprises:
and step 300, obtaining attenuation times or amplification times.
And obtaining the attenuation times or amplification times of the bias voltage signals according to the attenuation times of the attenuation network. Each attenuation multiple of the attenuation network corresponds to an attenuation multiple of one bias voltage signal, and each attenuation multiple of the attenuation network corresponds to an amplification multiple of one bias voltage signal.
Under the same passive attenuation gain, the small voltage gear and the large voltage gear of the digital oscilloscope have the same offset voltage range, but in the small voltage gear, the large offset range has little practical application significance. In this embodiment, an adjustable bias gain circuit is added between the bias adjusting circuit and the impedance transforming network. Under the same passive attenuation gain, the small voltage gear and the large voltage gear have different bias voltage ranges, the small gear has a smaller bias voltage range, and the large gear has a larger bias voltage range. The smaller bias voltage range of the small gear is realized by setting the gain of the bias gain circuit to be smaller than 1, which is equivalent to attenuation, and meanwhile, the temperature drift voltage generated in the front is also attenuated, so that the effect of reducing the temperature drift is achieved. The temperature drift attenuation method disclosed in the embodiment of the application improves the temperature drift from the perspective of hardware, has better real-time performance, and does not increase the calculation load of a system.
The method for attenuating the temperature drift comprises the steps of firstly, obtaining a vertical gear setting value of a digital oscilloscope; and then, attenuating or amplifying the bias voltage signal output by the bias adjusting circuit according to the vertical gear setting value, and outputting the attenuated or amplified bias voltage signal to the impedance transformation network, so that the attenuated or amplified bias voltage signal and the output signal of the attenuation network are superposed by the impedance transformation network, and the temperature drift phenomenon of the digital oscilloscope during waveform display is attenuated. Because the bias voltage signal is adjusted according to the vertical gear setting value, the attenuation of the temperature drift phenomenon is realized, and the waveform display effect of the digital oscilloscope is further enhanced, so that the user experience is improved.
Those skilled in the art will appreciate that all or part of the functions of the various methods in the above embodiments may be implemented by hardware, or may be implemented by computer programs. When all or part of the functions of the above embodiments are implemented by a computer program, the program may be stored in a computer-readable storage medium, and the storage medium may include: a read only memory, a random access memory, a magnetic disk, an optical disk, a hard disk, etc., and the program is executed by a computer to realize the above functions. For example, the program may be stored in a memory of the device, and when the program in the memory is executed by the processor, all or part of the functions described above may be implemented. In addition, when all or part of the functions in the above embodiments are implemented by a computer program, the program may be stored in a storage medium such as a server, another computer, a magnetic disk, an optical disk, a flash disk, or a portable hard disk, and may be downloaded or copied to a memory of a local device, or may be version-updated in a system of the local device, and when the program in the memory is executed by a processor, all or part of the functions in the above embodiments may be implemented.
The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (10)
1. A digital oscilloscope is characterized by comprising a controller, an attenuation network, an impedance transformation network, a first adjustable gain amplifier, an analog-to-digital converter, a bias adjusting circuit, a bias gain circuit, a digital-to-analog converter and a display;
the attenuation network is connected with the impedance transformation network and is used for attenuating an input signal input into the digital oscilloscope to obtain a first adjusting signal and outputting the first adjusting signal to the impedance transformation network;
the digital-to-analog converter is respectively connected with the controller and the offset adjusting circuit, and is used for converting offset codes of a digital signal output by the controller into offset code signals of analog signals and sending the offset code signals to the offset adjusting circuit;
the bias adjusting circuit is connected with the bias gain circuit and used for generating a first analog bias voltage signal according to the bias coding signal and sending the first analog bias voltage signal to the bias gain circuit;
the bias gain circuit is connected with the impedance transformation network and is used for attenuating or amplifying the first analog bias voltage signal according to gear setting parameters to obtain a second analog bias voltage signal and sending the second analog bias voltage signal to the impedance transformation network;
the impedance transformation network is connected with the first adjustable gain amplifier and used for acquiring a superposed signal according to the first adjusting signal and the second analog bias voltage signal and sending the superposed signal to the first adjustable gain amplifier;
the first adjustable gain amplifier is respectively connected with the controller and the analog-to-digital converter, and is used for amplifying or attenuating the superposed signal according to the configuration gain parameter output by the controller to obtain a second adjusting signal and sending the second adjusting signal to the analog-to-digital converter;
the analog-to-digital converter is connected with the controller and is used for converting the second adjusting signal into a digital waveform signal and sending the digital waveform signal to the controller;
the controller is respectively connected with the display, the bias gain circuit and the digital-to-analog converter; the controller is used for sending the gear setting parameter to the bias gain circuit according to the current vertical gear setting value of the digital oscilloscope; the controller is further configured to send a preset offset adjustment parameter to the digital-to-analog converter, so that the digital-to-analog converter converts the offset adjustment parameter into the offset encoding signal of the analog signal; the controller is further configured to obtain a first display driving signal according to the digital waveform signal, and send the first display driving signal to the display, so that the display displays the first waveform signal according to the first display driving signal.
2. The digital oscilloscope of claim 1, wherein the controller is configured to send the gear setting parameter to the bias gain circuit according to a current vertical gear setting value of the digital oscilloscope, and comprises:
when the vertical gear setting value of the digital oscilloscope is not greater than a first gear value, the gear setting parameter output to the bias gain circuit by the controller is a low gear parameter;
under the condition of the low gear parameter, the bias gain circuit attenuates the first analog bias voltage signal according to the low gear parameter to obtain a second analog bias voltage signal; wherein the attenuation multiple is greater than 1.
3. The digital oscilloscope of claim 1, wherein the controller is configured to send the gear setting parameter to the bias gain circuit according to a current vertical gear setting value of the digital oscilloscope, and comprises:
when the vertical gear setting value of the digital oscilloscope is larger than a first gear value, the gear setting parameter output to the bias gain circuit by the controller is a high gear parameter;
under the condition of the high gear parameter, the bias gain circuit amplifies the first analog bias voltage signal according to the high gear parameter to obtain a second analog bias voltage signal; wherein the magnification is not less than 1.
4. The digital oscilloscope of any of claims 2 or 3, wherein the attenuation or amplification of the first analog bias voltage signal by the bias gain circuit is obtained according to the attenuation of the attenuation network; each attenuation multiple of the attenuation network corresponds to an attenuation multiple of one first analog bias voltage signal, and each attenuation multiple of the attenuation network corresponds to an amplification multiple of one first analog bias voltage signal.
5. The attenuation temperature drift method for the digital oscilloscope is characterized by comprising an impedance transformation network, a bias adjusting circuit and an attenuation network, and comprises the following steps:
acquiring a vertical gear setting value of the digital oscilloscope;
and attenuating or amplifying a bias voltage signal output by a bias adjusting circuit of the digital oscilloscope according to the vertical gear setting value, and outputting the attenuated or amplified bias voltage signal to an impedance transformation network of the digital oscilloscope, so that the attenuated or amplified bias voltage signal is superposed with an output signal of the attenuation network of the digital oscilloscope by the impedance transformation network, and the temperature drift phenomenon of a displayed waveform of the digital oscilloscope is attenuated.
6. The attenuation temperature drift method according to claim 5, wherein the attenuating or amplifying the bias voltage signal output by the bias adjusting circuit of the digital oscilloscope according to the vertical gear setting value comprises:
when the vertical gear setting value of the digital oscilloscope is not greater than the first gear value, attenuating a bias voltage signal output by a bias adjusting circuit of the digital oscilloscope; wherein the attenuation multiple is greater than 1.
7. The attenuation temperature drift method according to claim 5, wherein the attenuating or amplifying the bias voltage signal output by the bias adjusting circuit of the digital oscilloscope according to the vertical gear setting value comprises:
amplifying a bias voltage signal output by a bias adjusting circuit of the digital oscilloscope when the vertical gear setting value of the digital oscilloscope is larger than a first gear value; wherein the magnification is not less than 1.
8. The attenuated temperature drift method of any one of claims 6 or 7, wherein said first shift value is NmV, and N is a positive number not greater than 5.
9. The attenuated temperature drift method of claim 5, further comprising:
obtaining the attenuation times or amplification times of the bias voltage signals according to the attenuation times of the attenuation network; each attenuation multiple of the attenuation network corresponds to an attenuation multiple of the bias voltage signal;
each attenuation multiple of the attenuation network corresponds to an amplification multiple of the bias voltage signal.
10. A computer-readable storage medium, characterized in that the medium has stored thereon a program which is executable by a processor to implement the method of decaying temperature drift according to any one of claims 5 to 9.
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