CN108802651B - Online correction device and correction method for temperature drift of noise coefficient analyzer - Google Patents

Online correction device and correction method for temperature drift of noise coefficient analyzer Download PDF

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CN108802651B
CN108802651B CN201810583648.4A CN201810583648A CN108802651B CN 108802651 B CN108802651 B CN 108802651B CN 201810583648 A CN201810583648 A CN 201810583648A CN 108802651 B CN108802651 B CN 108802651B
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noise coefficient
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coefficient analyzer
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CN108802651A (en
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魏连成
许建华
梁胜利
宋青娥
郑利颖
李文军
薛龙
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CETC 41 Institute
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
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    • G01R35/005—Calibrating; Standards or reference devices, e.g. voltage or resistance standards, "golden" references
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Abstract

The invention discloses an online correction device and a correction method for temperature drift of a noise coefficient analyzer, belonging to the technical field of electronic test. The invention can automatically start the online calibration function according to the change of the internal temperature of the noise coefficient analyzer case, avoids the defect that whether recalibration is needed or not is determined manually according to the measurement result and the change of the environmental temperature, and reduces the technical requirements on measuring personnel; the input port of the noise coefficient analyzer is not required to be removed when the on-line calibration is carried out, the tested piece is not required to be removed, the noise source is reconnected to the input port of the noise coefficient analyzer for calibration, the calibration convenience and the measurement efficiency are improved, the risk that measurement errors are introduced due to the fact that the performance index of the noise coefficient analyzer is not calibrated in time is reduced, and the measurement precision is improved.

Description

Online correction device and correction method for temperature drift of noise coefficient analyzer
Technical Field
The invention belongs to the technical field of electronic testing, and particularly relates to an online correction device and a correction method for temperature drift of a noise coefficient analyzer.
Background
Any circuitry generates noise, limiting the ability of the circuitry and system to receive and process weak signals. The noise coefficient is one of the most important parameters of the quantization circuit for processing weak signal capability, and the technical progress of electronic equipment and equipment such as microwave and millimeter wave communication, radar, navigation, precision guidance and the like is closely related to the increasingly improved receiver technology, wherein the important aspect is to reduce the noise generated by the receiver per se as much as possible and reduce the noise coefficient. With the development of equipment technology, the requirements on low-noise devices are more and more urgent, higher and higher requirements are also provided for the measurement accuracy of noise coefficient indexes, and the high-accuracy noise coefficient measurement has important significance for optimizing the size, weight, cost and performance of the whole machine and improving the reliability of a system.
The noise coefficient is usually measured by a noise coefficient analyzer, calibration must be performed first before measurement, a noise source which is accurately calibrated is connected to an input port of the noise coefficient analyzer during calibration, and two error parameters, namely the noise coefficient and the gain bandwidth product of the noise coefficient analyzer can be determined by respectively measuring the noise power output by the noise source in a cold state and a hot state, the characteristics of which are accurately known. The whole result of a secondary cascade system consisting of the tested piece and the noise coefficient analyzer is actually obtained when the tested piece is measured, and the accurate noise coefficient measurement result of the tested piece can be obtained by adopting a secondary error correction technology to remove the influence of the error introduced by the noise coefficient analyzer on the measurement result according to the calibration result. In order to ensure the accuracy of error correction after calibration, it is required that the performance characteristics of the noise figure analyzer itself after calibration must be kept constant.
However, the performance indexes of various microwave and millimeter wave semiconductor devices drift with the change of temperature, and indexes such as the frequency conversion loss of a mixer in a receiving channel of a noise coefficient analyzer, the gain of a microwave and millimeter wave amplifier and the like change with the change of temperature. The receiving circuit of the noise coefficient analyzer has high sensitivity and large gain, and the noise coefficient of the circuit module is a function of temperature, so that the performance characteristic of a receiving channel changes obviously along with the temperature. When the temperature inside the chassis of the noise coefficient analyzer changes, the accuracy of error correction is affected and measurement errors are introduced due to the fact that the actual performance index of the noise coefficient analyzer is different from the actual performance index of the noise coefficient analyzer during calibration. To eliminate the measurement error, the tested piece must be removed, the noise source is connected to the input port of the noise coefficient analyzer, and the calibration is performed again, which brings inconvenience to the measurement.
As shown in fig. 1, a receiving circuit of a conventional noise coefficient analyzer is limited by performance indexes of existing devices, and an input signal is first divided into a radio frequency band and a microwave band by a band switch to be respectively subjected to frequency mixing reception. The received signal in the radio frequency band is first low-pass filtered after passing through the band switch to filter out image frequency and other high-order signals, so as to ensure that only the required measuring signal is received. Then the variable radio frequency signal is changed into a fixed intermediate frequency signal through radio frequency preposed low noise amplification and radio frequency superheterodyne mixing reception. Signals in a microwave band enter a microwave receiving circuit after passing through a band switch, are pre-amplified firstly, and then are subjected to tunable band-pass filtering, the center frequency of a band-pass filter changes along with the receiving frequency to filter out image frequency signals and other high-order signals, so that only required microwave band signals are received, then microwave signals with different frequencies are changed into fixed intermediate frequency signals through a microwave superheterodyne mixing receiving circuit, and the superheterodyne mixing receiving circuit for both radio frequency and microwave generally comprises a multistage mixing circuit. Intermediate frequency signals obtained by radio frequency and microwave frequency mixing are combined into one path after being subjected to intermediate frequency amplification and an intermediate frequency switch, the amplitude of the intermediate frequency signals is conditioned to be suitable for being processed by an analog-to-digital converter through an intermediate frequency conditioning circuit, the analog intermediate frequency signals are converted into digital intermediate frequency signals through the analog-to-digital converter, the power value of noise signals can be obtained through further processing, a noise coefficient analyzer respectively measures the noise power output by a tested piece under the excitation of a noise source in a hot state and a cold state, and then the noise coefficient and the gain value of the tested piece can be measured.
When a measured piece is measured, the noise power measured by the noise coefficient analyzer is noise which is generated by the two-stage cascade system of the measured piece and the noise coefficient analyzer together, so that the performance characteristic of the noise coefficient analyzer needs to be determined through calibration, and the influence of the noise coefficient analyzer on the measurement precision is removed through error correction during measurement, so that the noise coefficient and the gain value of the measured piece can be accurately obtained.
1. Calibrating noise figure analyzer
And (3) connecting a noise source with accurately known thermal and cold output noise power characteristics to an input port of a noise coefficient analyzer during calibration, and measuring corresponding output noise power. The noise temperature of the noise source in the hot state and the cold state is accurately known and is respectively set as ThAnd TcThe over-noise ratio (ENR) of the noise source is defined as:
Figure GDA0002454532230000021
in equation (1), T0Referred to as standard noise temperature, equal to 290 k. The noise power measured by the noise coefficient analyzer when the noise source is in a hot state and a cold state is respectively N2_ONAnd N2_OFFThe over-noise ratio of the noise source used in calibration is ENRCALAt cold temperature TcCALThen there are:
Figure GDA0002454532230000022
Figure GDA0002454532230000023
Y2is the Y factor, F, of the noise coefficient analyzer itself2The noise figure of the noise figure analyzer itself is determined through the above calibration process.
2. Measurement and error correction
When in measurement, a noise source is connected to an input port of a tested piece, an output port of the tested piece is connected with an input port of a noise coefficient analyzer, and the noise powers measured by the noise coefficient analyzer in two excitation states of a thermal state and a cold state of the noise source are respectively set to be N12_ONAnd N12_OFFThe over-noise ratio of the noise source used in the measurement is ENRMEASAt cold temperature TcMEAS,: then there is
Figure GDA0002454532230000031
Figure GDA0002454532230000032
F12The whole noise coefficient of a two-stage cascade system consisting of a tested piece and a noise coefficient analyzer, and the gain G of the tested piece1Determined by the following equation:
Figure GDA0002454532230000033
according to the noise coefficient cascade formula, the noise coefficient F of the tested piece1Determined by the following equation:
Figure GDA0002454532230000034
thus, the gain G of the tested piece can be measured by calibrating before measurement and correcting errors during measurement1And noise factor F1The exact value of (c).
The main disadvantage of the prior art is that the performance index of the whole machine cannot drift after the noise coefficient analyzer completes calibration, but the performance index of most microwave millimeter wave devices changes with temperature, when the temperature inside a chassis of the noise coefficient analyzer changes, the noise coefficient and the gain of a receiving circuit of the noise coefficient analyzer inevitably change, the difference between the actual performance index of the whole machine and the performance index during calibration inevitably introduces a measurement error when secondary error correction is performed in the measurement process, the error is removed, measurement must be terminated, a tested part is dismantled, and a noise source is reconnected to an input port of the noise coefficient analyzer for calibration. This recalibration process not only affects the efficiency of the measurement, but also results in less accurate measurements because the measurement personnel cannot determine when the recalibration should be performed.
Disclosure of Invention
Aiming at the technical problems in the prior art, the invention provides the online correction device and the correction method for the temperature drift of the noise coefficient analyzer, which have reasonable design, overcome the defects of the prior art and have good effect.
In order to achieve the purpose, the invention adopts the following technical scheme:
an online correction device for the temperature drift of a noise coefficient analyzer comprises an online calibration circuit, a correction switch and a noise source, wherein the online calibration circuit comprises the calibration switch and the noise source;
the calibration switch adopts a single-pole double-throw switch form and comprises a common port, a measurement port and a calibration port which are three ports; the public port is connected with a band switch at the rear end of the public port, and the public port is respectively connected with a noise source of the calibration port or the measurement port to receive the input of a measurement signal; when the input port of the noise coefficient analysis is calibrated in normal time measurement, the switch is switched to the measurement port, and the public port is connected with the measurement port at the moment; when online calibration is required, the switch is switched to the calibration port, and the common port is connected with the noise source of the calibration port.
Preferably, the correction device comprises a thermostatic bath structure in which the source of noise is arranged.
Preferably, the calibration switch is an electromechanical switch.
Preferably, the apparatus further comprises a temperature monitoring circuit for detecting the temperature inside the housing of the noise figure analyzer.
In addition, the invention also provides an online correction method for the temperature drift of the noise coefficient analyzer, which adopts the online correction device for the temperature drift of the noise coefficient analyzer, and specifically comprises the following steps:
step 1: calibrating a noise coefficient analyzer;
step 1.1: connecting a noise source with known thermal and cold output noise power characteristics to an input port of a noise coefficient analyzer during calibration, switching a calibration switch to a measurement port, and setting the noise power measured by the noise coefficient analyzer to be N respectively when the noise source is in a thermal state and a cold state2_ONAnd N2_OFFThe over-noise ratio of the noise source used in calibration is ENRCALAt cold temperature TcCALThen, there are:
Figure GDA0002454532230000041
Figure GDA0002454532230000042
wherein, T0Referred to as standard noise temperature, equal to 290 k; y is2Y factor of noise coefficient analyzer complete machine using input port as reference plane；F2The local noise coefficient of the noise coefficient analyzer takes the input port as a reference plane;
step 1.2: the calibration switch is switched to a calibration port, and the noise powers measured by the noise coefficient analyzer in the hot state and the cold state of the noise source in the line calibration circuit are respectively N2_ONINTAnd N2_OFFINTThe over-noise ratio of the noise source in the on-line calibration circuit is ENRINTAt cold temperature TcINTThen, there are:
Figure GDA0002454532230000043
Figure GDA0002454532230000044
wherein, Y2INTIs the Y factor, F of the noise coefficient analyzer using the calibration port of the calibration switch as the reference plane2INTThe local noise coefficient of the whole noise coefficient analyzer takes a calibration port of a calibration switch as a reference plane;
step 2: measuring the noise coefficient and correcting the error of the measured piece; the method specifically comprises the following steps:
when in measurement, a noise source is connected to an input port of a measured piece, an output port of the measured piece is connected with an input port of a noise coefficient analyzer, a calibration switch is switched to a measurement port, and noise powers measured by the noise coefficient analyzer in two excitation states of a thermal state and a cold state of the noise source are respectively set to be N12_ONAnd N12_OFFThe over-noise ratio of the noise source used in the measurement is ENRMEASAt cold temperature TcMEASThen there is
Figure GDA0002454532230000051
Figure GDA0002454532230000052
Wherein, Y12Is a measured piece and noiseThe overall Y factor of a secondary cascade system consisting of a coefficient analyzer; f12The noise coefficient of the whole noise coefficient of a secondary cascade system consisting of a tested piece and a noise coefficient analyzer;
gain G of the measured part1Determined by equation (14):
Figure GDA0002454532230000053
according to the noise coefficient cascade formula, the noise coefficient F of the tested piece1Determined by equation (15):
Figure GDA0002454532230000054
by calibrating and correcting the measurement error, the gain G of the measured piece can be measured1And noise factor F1The exact value of (d);
and step 3: the temperature drift correction calibration method specifically comprises the following steps:
when a temperature monitoring circuit in the noise coefficient analyzer detects that the temperature change in the case exceeds 5 ℃, a temperature drift calibration function is started first, the calibration switch is switched to a calibration port at the moment, and the noise powers measured by the noise coefficient analyzer in the on-line calibration circuit when a noise source is in a hot state and a cold state are respectively N2_ONINTSAnd N2_OFFINTSThe over-noise ratio of the noise source in the on-line calibration circuit remains unchanged to ENRINTAt cold temperature TcINTThen, there are:
Figure GDA0002454532230000055
Figure GDA0002454532230000056
wherein, Y2INTSThe Y factor and F of the whole noise coefficient analyzer using the calibration port of the calibration switch as the reference plane when the temperature drift occurs to the performance of the internal circuit of the noise coefficient analyzer2INTSFor in noise figure analyzersThe local noise coefficient of the whole noise coefficient analyzer takes the calibration port of the calibration switch as a reference plane when the performance of the partial circuit is subjected to temperature drift;
according to the temperature drift calibration result, the local noise coefficient of the noise coefficient analyzer which takes the input port as the reference plane after the temperature drift is analyzed and generated is corrected to be F2SThe value is shown in formula (18):
Figure GDA0002454532230000057
wherein, F2The local noise coefficient of the noise coefficient analyzer with the input port as the reference plane determined by the formula (9) in the step 1.1; f2INTThe local noise coefficient of the whole noise coefficient analyzer with the calibration port of the calibration switch as a reference plane determined by the formula (11) in the step 1.2; f2INTSWhen the performance of the internal circuit of the noise coefficient analyzer determined by the formula (17) in the step 3 is subjected to temperature drift, the local noise coefficient of the whole noise coefficient analyzer with the calibration port of the calibration switch as a reference plane is obtained;
and 4, step 4: after the temperature drift calibration is completed, the calibration switch is switched to the measurement port again for measurement of the measured piece, and the noise power measured by the noise coefficient analyzer in the two excitation states of the noise source in the hot state and the cold state is respectively set to be N12_ONAnd N12_OFFThe over-noise ratio of the noise source used in the measurement is ENRMEASAt cold temperature TcMEAS；
According to the temperature drift calibration result, gain G of the tested piece is obtained1And noise factor F1The formula of (c) is modified as follows:
Figure GDA0002454532230000061
wherein N is2_ONAnd N2_OFFMeasured during calibration in step 1.1, ENRCALFor the over-noise ratio, N, of the noise source used in the calibration of step 1.12_ONINTAnd N2_OFFINTMeasurement while performing step 1.2 calibrationTo obtain N2_ONINTSAnd N2_OFFINSMeasuring and obtaining the temperature drift correction calibration in the step 3;
Figure GDA0002454532230000062
in the above formula, F2SDetermined by step 3 and equation (18), F12Noise power N measured by step 412_ON、N12_OFFAnd formula (12) and formula (13), G1 is determined by step 4 and formula (19);
when the noise coefficient analyzer monitors that the temperature change in the case is overlarge, the temperature drift calibration function is automatically started, and the gain G of the tested piece is calculated by adopting a formula (19) and a formula (20) according to the temperature drift calibration result1And noise factor F1The measuring error of the noise coefficient analyzer caused by temperature drift can be corrected.
The invention has the following beneficial technical effects:
the invention provides a device capable of correcting temperature drift error of a noise coefficient analyzer and carrying out online calibration, wherein a primary online calibration circuit is introduced on the basis of a receiving circuit of a traditional noise coefficient analyzer, when the temperature change in a case is detected by the instrument to exceed a certain value, the internal online calibration circuit is automatically switched to for calibration, and a tested piece does not need to be detached to reconnect a noise source to an input port of the noise coefficient analyzer during online calibration, so that the convenience of calibration is greatly improved, and the professional technical requirements on instrument users are reduced;
the invention provides a method for correcting temperature drift errors of a noise coefficient analyzer, which improves a calculation formula for obtaining gain and noise coefficient of a tested piece according to an online calibration result and a port calibration result before measurement, removes the influence of the drift of the performance index of the whole noise coefficient analyzer on the measurement precision when the temperature in a case of the noise coefficient analyzer changes after the port calibration, and improves the measurement precision;
the invention can automatically start the online calibration function according to the change of the internal temperature of the noise coefficient analyzer case, avoids the defect that whether recalibration is needed or not is determined manually according to the measurement result and the change of the environmental temperature, and reduces the technical requirements on measuring personnel;
the input port of the noise coefficient analyzer is not required to be removed when the on-line calibration is carried out, the tested piece is not required to be removed, the noise source is reconnected to the input port of the noise coefficient analyzer for calibration, the calibration convenience and the measurement efficiency are improved, the risk that measurement errors are introduced due to the fact that the performance index of the noise coefficient analyzer is not calibrated in time is reduced, and the measurement precision is improved.
Drawings
Fig. 1 is a diagram of a conventional noise figure analyzer receiving circuit.
FIG. 2 is a circuit diagram of the online correction of the temperature drift of the noise figure analyzer of the present invention.
Detailed Description
The invention is described in further detail below with reference to the following figures and detailed description:
example 1:
an online correction device for the temperature drift of a noise coefficient analyzer is disclosed, the circuit of which is shown in fig. 2 and comprises an online calibration circuit, wherein the online calibration circuit comprises a calibration switch and a noise source;
the calibration switch adopts a single-pole double-throw switch form and comprises a common port, a measurement port and a calibration port which are three ports; the output of the public port is connected with a waveband switch at the rear end of the public port, and the public port is respectively connected with a noise source of the calibration port or the measurement port to receive the input of a measurement signal; when the input port of the noise coefficient analysis is calibrated in normal time measurement, the switch is switched to the measurement port, and the public port is connected with the measurement port at the moment; when online calibration is required, the switch is switched to the calibration port, and the common port is connected with the noise source of the calibration port.
The correction device comprises a thermostatic bath structure, and a noise source is arranged in the thermostatic bath structure.
The calibration switch is an electromechanical switch.
The device also comprises a temperature monitoring circuit for detecting the temperature inside the case of the noise coefficient analyzer.
Example 2:
on the basis of the above embodiment, the present invention further provides an online correction method for the temperature drift of the noise coefficient analyzer, which specifically includes the following steps:
step 1: calibrating a noise coefficient analyzer;
step 1.1: connecting a noise source with known thermal and cold output noise power characteristics to an input port of a noise coefficient analyzer during calibration, switching a calibration switch to a measurement port, and setting the noise power measured by the noise coefficient analyzer to be N respectively when the noise source is in a thermal state and a cold state2_ONAnd N2_OFFThe over-noise ratio of the noise source used in calibration is ENRCALAt cold temperature TcCALThen, there are:
Figure GDA0002454532230000071
Figure GDA0002454532230000072
wherein, T0Referred to as standard noise temperature, equal to 290 k; y is2The Y factor of the whole noise coefficient analyzer with the input port as a reference plane; f2The local noise coefficient of the noise coefficient analyzer takes the input port as a reference plane;
step 1.2: the calibration switch is switched to a calibration port, and the noise powers measured by the noise coefficient analyzer in the hot state and the cold state of the noise source in the line calibration circuit are respectively N2_ONINTAnd N2_OFFINTThe over-noise ratio of the noise source in the on-line calibration circuit is ENRINTAt cold temperature TcINTThen, there are:
Figure GDA0002454532230000081
Figure GDA0002454532230000082
wherein, Y2INTTo calibrate the calibration port of the switchY factor, F of noise coefficient analyzer for reference plane2INTThe local noise coefficient of the whole noise coefficient analyzer takes a calibration port of a calibration switch as a reference plane;
step 2: measuring the noise coefficient and correcting the error of the measured piece; the method specifically comprises the following steps:
when in measurement, a noise source is connected to an input port of a measured piece, an output port of the measured piece is connected with an input port of a noise coefficient analyzer, a calibration switch is switched to a measurement port, and noise powers measured by the noise coefficient analyzer in two excitation states of a thermal state and a cold state of the noise source are respectively set to be N12_ONAnd N12_OFFThe over-noise ratio of the noise source used in the measurement is ENRMEASAt cold temperature TcMEASThen there is
Figure GDA0002454532230000083
Figure GDA0002454532230000084
Wherein, Y12The integral Y factor of a secondary cascade system consisting of a tested piece and a noise coefficient analyzer; f12The noise coefficient of the whole noise coefficient of a secondary cascade system consisting of a tested piece and a noise coefficient analyzer;
gain G of the measured part1Determined by equation (14):
Figure GDA0002454532230000085
according to the noise coefficient cascade formula, the noise coefficient F of the tested piece1Determined by equation (15):
Figure GDA0002454532230000086
by calibrating and correcting the measurement error, the gain G of the measured piece can be measured1And noise factor F1To makeConfirming the value;
and step 3: the temperature drift correction calibration method specifically comprises the following steps:
when a temperature monitoring circuit in the noise coefficient analyzer detects that the temperature change in the case exceeds 5 ℃, a temperature drift calibration function is started first, the calibration switch is switched to a calibration port at the moment, and the noise powers measured by the noise coefficient analyzer in the on-line calibration circuit when a noise source is in a hot state and a cold state are respectively N2_ONINTSAnd N2_OFFINTSThe over-noise ratio of the noise source in the on-line calibration circuit remains unchanged to ENRINTAt cold temperature TcINTThen, there are:
Figure GDA0002454532230000091
Figure GDA0002454532230000092
wherein, Y2INTSThe Y factor and F of the whole noise coefficient analyzer using the calibration port of the calibration switch as the reference plane when the temperature drift occurs to the performance of the internal circuit of the noise coefficient analyzer2INTSThe local noise coefficient of the whole noise coefficient analyzer takes the calibration port of the calibration switch as a reference plane when the performance of the internal circuit of the noise coefficient analyzer generates temperature drift;
according to the temperature drift calibration result, the local noise coefficient of the noise coefficient analyzer which takes the input port as the reference plane after the temperature drift is analyzed and generated is corrected to be F2SThe value is shown in formula (18):
Figure GDA0002454532230000093
wherein, F2The local noise coefficient of the noise coefficient analyzer with the input port as the reference plane determined by the formula (9) in the step 1.1; f2INTThe local noise coefficient of the whole noise coefficient analyzer with the calibration port of the calibration switch as a reference plane determined by the formula (11) in the step 1.2; f2INTSWhen the performance of the internal circuit of the noise coefficient analyzer determined by the formula (17) in the step 3 is subjected to temperature drift, the local noise coefficient of the whole noise coefficient analyzer with the calibration port of the calibration switch as a reference plane is obtained;
and 4, step 4: after the temperature drift calibration is completed, the calibration switch is switched to the measurement port again for measurement of the measured piece, and the noise power measured by the noise coefficient analyzer in the two excitation states of the noise source in the hot state and the cold state is respectively set to be N12_ONAnd N12_OFFThe over-noise ratio of the noise source used in the measurement is ENRMEASAt cold temperature TcMEAS；
According to the temperature drift calibration result, gain G of the tested piece is obtained1And noise factor F1The formula of (c) is modified as follows:
Figure GDA0002454532230000094
wherein N is2_ONAnd N2_OFFMeasured during calibration in step 1.1, ENRCALFor the over-noise ratio, N, of the noise source used in the calibration of step 1.12_ONINTAnd N2_OFFINTMeasured during calibration in step 1.2, N2_ONINTSAnd N2_OFFINSMeasuring and obtaining the temperature drift correction calibration in the step 3;
Figure GDA0002454532230000095
in the above formula, F2SDetermined by step 3 and equation (18), F12Noise power N measured by step 412_ON、N12_OFFAnd formula (12) and formula (13), G1 is determined by step 4 and formula (19);
when the noise coefficient analyzer monitors that the temperature change in the case is overlarge, the temperature drift calibration function is automatically started, and the gain G of the tested piece is calculated by adopting a formula (19) and a formula (20) according to the temperature drift calibration result1And noise factor F1The measuring error of the noise coefficient analyzer caused by temperature drift can be corrected.
It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.

Claims (1)

1. An on-line correction method for the temperature drift of a noise coefficient analyzer is characterized by comprising the following steps: the device comprises an online calibration circuit, a temperature drift correction circuit and a temperature drift correction circuit, wherein the online calibration circuit comprises a calibration switch and a noise source;
the calibration switch adopts a single-pole double-throw switch form and comprises a common port, a measurement port and a calibration port which are three ports; the public port is connected with a band switch at the rear end of the public port, and the public port is respectively connected with a noise source of the calibration port or the measurement port to receive the input of a measurement signal; when the input port of the noise coefficient analysis is calibrated in normal time measurement, the switch is switched to the measurement port, and the public port is connected with the measurement port at the moment; when online calibration is needed, the switch is switched to the calibration port, and the public port is connected with a noise source of the calibration port at the moment; the method specifically comprises the following steps:
step 1: calibrating a noise coefficient analyzer;
step 1.1: connecting a noise source with known thermal and cold output noise power characteristics to an input port of a noise coefficient analyzer during calibration, switching a calibration switch to a measurement port, and setting the noise power measured by the noise coefficient analyzer to be N respectively when the noise source is in a thermal state and a cold state2_ONAnd N2_OFFThe over-noise ratio of the noise source used in calibration is ENRCALAt cold temperature TcCALThen, there are:
Figure FDA0002454532220000011
Figure FDA0002454532220000012
wherein, T0Referred to as standard noise temperature, equal to 290 k; y is2The Y factor of the whole noise coefficient analyzer with the input port as a reference plane; f2The local noise coefficient of the noise coefficient analyzer takes the input port as a reference plane;
step 1.2: the calibration switch is switched to a calibration port, and the noise powers measured by the noise coefficient analyzer in the hot state and the cold state of the noise source in the line calibration circuit are respectively N2_ONINTAnd N2_OFFINTThe over-noise ratio of the noise source in the on-line calibration circuit is ENRINTAt cold temperature TcINTThen, there are:
Figure FDA0002454532220000013
Figure FDA0002454532220000014
wherein, Y2INTIs the Y factor, F of the noise coefficient analyzer using the calibration port of the calibration switch as the reference plane2INTThe local noise coefficient of the whole noise coefficient analyzer takes a calibration port of a calibration switch as a reference plane;
step 2: measuring the noise coefficient and correcting the error of the measured piece; the method specifically comprises the following steps:
when in measurement, a noise source is connected to an input port of a measured piece, an output port of the measured piece is connected with an input port of a noise coefficient analyzer, a calibration switch is switched to a measurement port, and noise powers measured by the noise coefficient analyzer in two excitation states of a thermal state and a cold state of the noise source are respectively set to be N12_ONAnd N12_OFFThe over-noise ratio of the noise source used in the measurement is ENRMEASAt cold temperature TcMEASThen there is
Figure FDA0002454532220000021
Figure FDA0002454532220000022
Wherein, Y12The integral Y factor of a secondary cascade system consisting of a tested piece and a noise coefficient analyzer; f12The noise coefficient of the whole noise coefficient of a secondary cascade system consisting of a tested piece and a noise coefficient analyzer;
gain G of the measured part1Determined by equation (14):
Figure FDA0002454532220000023
according to the noise coefficient cascade formula, the noise coefficient F of the tested piece1Determined by equation (15):
Figure FDA0002454532220000024
by calibrating and correcting the measurement error, the gain G of the measured piece can be measured1And noise factor F1The exact value of (d);
and step 3: the temperature drift correction calibration method specifically comprises the following steps:
when a temperature monitoring circuit in the noise coefficient analyzer detects that the temperature change in the case exceeds 5 ℃, a temperature drift calibration function is started first, the calibration switch is switched to a calibration port at the moment, and the noise powers measured by the noise coefficient analyzer in the on-line calibration circuit when a noise source is in a hot state and a cold state are respectively N2_ONINTSAnd N2_OFFINTSThe over-noise ratio of the noise source in the on-line calibration circuit remains unchanged to ENRINTAt cold temperature TcINTThen, there are:
Figure FDA0002454532220000025
Figure FDA0002454532220000026
wherein, Y2INTSThe Y factor and F of the whole noise coefficient analyzer using the calibration port of the calibration switch as the reference plane when the temperature drift occurs to the performance of the internal circuit of the noise coefficient analyzer2INTSThe local noise coefficient of the whole noise coefficient analyzer takes the calibration port of the calibration switch as a reference plane when the performance of the internal circuit of the noise coefficient analyzer generates temperature drift;
according to the temperature drift calibration result, the local noise coefficient of the noise coefficient analyzer which takes the input port as the reference plane after the temperature drift is analyzed and generated is corrected to be F2SThe value is shown in formula (18):
Figure FDA0002454532220000027
wherein, F2The local noise coefficient of the noise coefficient analyzer with the input port as the reference plane determined by the formula (9) in the step 1.1; f2INTThe local noise coefficient of the whole noise coefficient analyzer with the calibration port of the calibration switch as a reference plane determined by the formula (11) in the step 1.2; f2INTSWhen the performance of the internal circuit of the noise coefficient analyzer determined by the formula (17) in the step 3 is subjected to temperature drift, the local noise coefficient of the whole noise coefficient analyzer with the calibration port of the calibration switch as a reference plane is obtained;
and 4, step 4: after the temperature drift calibration is completed, the calibration switch is switched to the measurement port again for measurement of the measured piece, and the noise power measured by the noise coefficient analyzer in the two excitation states of the noise source in the hot state and the cold state is respectively set to be N12_ONAnd N12_OFFThe over-noise ratio of the noise source used in the measurement is ENRMEASAt cold temperature TcMEAS；
According to the temperature drift calibration result, gain G of the tested piece is obtained1And noise factor F1The formula of (c) is modified as follows:
Figure FDA0002454532220000031
wherein N is2_ONAnd N2_OFFMeasured during calibration in step 1.1, ENRCALFor the over-noise ratio, N, of the noise source used in the calibration of step 1.12_ONINTAnd N2_OFFINTMeasured during calibration in step 1.2, N2_ONINTSAnd N2_OFFINSMeasuring and obtaining the temperature drift correction calibration in the step 3;
Figure FDA0002454532220000032
in the above formula, F2SDetermined by step 3 and equation (18), F12Noise power N measured by step 412_ON、N12_OFFAnd formula (12) and formula (13), G1 is determined by step 4 and formula (19);
when the noise coefficient analyzer monitors that the temperature change in the case is overlarge, the temperature drift calibration function is automatically started, and the gain G of the tested piece is calculated by adopting a formula (19) and a formula (20) according to the temperature drift calibration result1And noise factor F1The measuring error of the noise coefficient analyzer caused by temperature drift can be corrected.
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