A noise temperature test method suitable for OTA test

Abstract

The application discloses a noise temperature testing method suitable for OTA testing, and aims at measuring the noise temperature of a device to be tested by using a method of air interface testing, and comprises the following steps: acquiring the noise temperature of an instrument according to a first testing system; constructing a second testing system, testing the noise temperature and gain of the whole second testing system; constructing a third testing system, testing the noise temperature value and gain of the whole third testing system, wherein the device to be tested is suitable for microwave millimeter wave modules, receivers, transmitters, packaged antennas and other devices and systems. The testing instrument can be a combination of a noise source and a signal analyzer, or other noise generating equipment and a receiving system. The measurement method calibrates the environmental temperature and the instrument before testing, and therefore has the characteristics of being simple, fast and high in precision for testing antenna radio frequency integrated modules and on-chip antenna modules.

Description

Technical Field

[0001] This invention relates to the field of microwave and millimeter-wave measurement, and specifically to a noise and temperature testing method suitable for OTA testing. Background Technology

[0002] Noise temperature (NT) is used as a key indicator of the performance of radio receivers, transmitters, or antenna arrays. Currently, the measurement method for noise temperature is still based on the traditional conducted method. However, with the increasing integration of systems, the conducted method is no longer suitable for testing devices with integrated antennas, such as antenna-in-package (AiP) devices.

[0003] NT is an important indicator for measuring the sensitivity of a receiver system. Antenna noise temperature is defined as the noise temperature of a receiver within a unit bandwidth at a specified frequency. If the noise temperature of the receiver output is the same as the noise temperature when the antenna is connected, then the noise temperature of the resistor is the noise temperature of the antenna.

[0004] For research on noise parameter testing of devices under test, the current common method is... Figure 2The conduction method shown is relatively simple to test, but it is only suitable for testing devices with dual / multi-port ports and cannot be used to test modules with integrated antennas. For example, in 2014, HFHsiao et al. used the cold source method and the Y-factor method to test the noise parameters of downconverters. The test results show that the cold source method is less affected by the reflection coefficient than the Y-factor method, but the cold source method has a larger calibration error for noise parameters. For OTA test noise research, when using traditional methods to measure antennas and front-end modules, the antenna under test (AUT) is usually facing the sky (Effect Study of Spectrum Analyzer Noise Floor on Antenna Noise Temperature Measurement Zhen-Dong WU, Shun-You QIN The Fifty Fourth Institute of CETC, Shijiazhuang 050081, PRCHINA), and the noise temperature of the antenna is obtained by switching the antenna stage. This measurement method is inconvenient, especially in mass production processes, where the measurement results are significantly affected by external environmental noise temperature and internal losses, which are closely related to the antenna's elevation angle. Furthermore, the RF switch is necessary, which introduces additional uncertainty to the noise results. Summary of the Invention

[0005] To address the above problems, this invention proposes a noise temperature measurement method suitable for OTA measurement.

[0006] The present invention is achieved by at least one of the following technical solutions.

[0007] A noise temperature testing method suitable for OTA testing includes the following steps:

[0008] a) Obtain the noise temperature T of the instrument based on the first test system. Instr ;

[0009] b) Construct a second test system and test the noise temperature T of the second test system. b and gain G b ;

[0010] c) Construct a third test system and test the noise temperature value T of the third test system. a and gain G a .

[0011] Furthermore, the first test system includes a first noise source NS, a first spectrum analyzer SA, and the required RF adapter. The first noise source is connected to the first spectrum analyzer via a test cable and the RF adapter. The frequency, intermediate frequency bandwidth, preamplifier, temperature, and ENR parameters in the first spectrum analyzer are set according to test requirements. The noise temperature of the first noise source when it is on and off is obtained, respectively. The Y factor of the system.

[0012] Furthermore, the noise temperature T of the instrument Instr Calculated using the following formula:

[0013]

[0014] Among them, T Instr and Y Instr These are the noise temperature and Y-factor of the first test system, respectively. and These are the noise temperatures of the first noise source when it is on and off, respectively.

[0015] Furthermore, the second system includes a second noise source, a second spectrum analyzer, two standard gain antennas with identical performance parameters, and the required radio frequency adapter, with a distance D between the two standard gain antennas.

[0016] Furthermore, the noise temperature T of the second test system b Calculated using the following formula:

[0017]

[0018]

[0019] In the formula, T ANT For the noise temperature of a single standard gain antenna, G ANT The gain of a single standard gain antenna, where T ANT and G ANT Including path loss in space; T Instr The noise temperature of the first test system; G b This represents the gain of the second test system.

[0020] Furthermore, the third test system includes a third noise source, a reference antenna, a device under test (DUT), test cables, a third spectrum analyzer, and the required RF adapters. The distance between the reference antenna and the DUT is D.

[0021] Furthermore, the device under test (DUT) is either a module integrating the antenna and RF module or a separate antenna under test.

[0022] Furthermore, when the device under test (DUT) is a receiving module, the noise temperature T of the DUT is... DUT,RX :

[0023]

[0024] In the formula, T a and G a For the noise temperature value and gain of the third test system, T Instr The noise temperature of the first test system; T b and G b For the noise temperature and gain of the second test system; G ANT The gain of a single standard gain antenna for the second test system.

[0025] Furthermore, when the device under test (DUT) is a transmitter module, the noise temperature T of the DUT is... DUT,TX :

[0026]

[0027] In the formula, T c and G c For the noise temperature value and gain of the third test system, T Instr The noise temperature of the first test system; T b and G b For the noise temperature and gain of the second test system; G ANT The gain of a single standard gain antenna for the second test system.

[0028] Furthermore, the device under test (DUT) includes a microwave / millimeter-wave module, a receiver, a transmitter, and a packaged antenna.

[0029] Compared with existing technologies, the beneficial effects of the present invention are as follows:

[0030] This invention employs a pair of standard gain antennas to measure modules with integrated antennas indoors. Therefore, the test results are less affected by external sky conditions, resulting in relatively stable measurement results. Furthermore, the noise temperature or noise factor of the device under test (DUT), whether it is the receiving module or the transmitting module, can be measured independently during the test. Attached Figure Description

[0031] Figure 1 This is a schematic diagram illustrating the principle of noise temperature calibration and testing using the open-circuit method in this embodiment.

[0032] Figure 2 This is a diagram of the NT test structure based on the conduction method;

[0033] Figure 3a This is a simulation model diagram of the reference antenna calibration for noise and temperature simulation verification based on the OTA method;

[0034] Figure 3b This is a simulation result of the reference antenna noise temperature.

[0035] Figure 3c Diagram of the test simulation model of the device under test;

[0036] Figure 3d This is a simulation result of the noise and temperature of the device under test. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] A noise temperature testing method suitable for over-the-air (OTA) testing is proposed. First, the concept of noise temperature and the expression for the noise temperature of a cascaded system are analyzed. The processes of noise temperature measurement using both the conducted method and the over-the-air method are then outlined. Next, the composition of noise temperature in over-the-air OTA measurement is analyzed. Simulations are performed based on the proposed measurement method, and the results are compared with those obtained using the conducted method. The comparison results show that this method is technically feasible for integrated antennas.

[0039] The noise temperature of a cascaded system can be expressed as:

[0040]

[0041] Where T1 and G1 represent the noise temperature and gain of the first-level module on the reference plane, T2 and G2 represent the noise temperature and gain of the second-level module, and so on, to obtain the noise temperature of the entire system.

[0042] The RF component under test is connected to a noise source and a spectrum analyzer (signal analyzer) via a coaxial cable. The total noise temperature T is measured. sys The noise temperature T at the receiver is divided into RX and the noise temperature T of the test piece DUT Two parts.

[0043] If the receiver's T Instr It can be calibrated, and the gain G of the device under test DUT Given that the measured component T DUT It can be calculated using formula (6):

[0044]

[0045] Since the ambient temperature during testing may not be 290K, while the ENR value of the noise source is the standard value measured at 290K, temperature calibration of the noise source is necessary before testing. That is, when... When the time comes, correction is performed according to equation (7).

[0046]

[0047] In the formula, ENR CORR ENR represents the corrected over-noise ratio of the noise source. CAL This represents the standard value of the over-noise ratio of the noise source before correction; T0 is the standard reference temperature of 290K. This refers to the noise temperature of the noise source when it is in the off state, i.e., the physical temperature of the noise source during the test.

[0048] In the air interface test, the horizontal distance between the transmitting antenna and the receiving antenna should meet the antenna far-field distance, as shown in formula (8), where R represents the test distance, D represents the antenna aperture, and λ represents the wavelength corresponding to the operating frequency of the test signal.

[0049]

[0050] Traditional methods for measuring the noise temperature of a DUT are based on the conduction method, and the specific measurement block diagram is as follows: Figure 2 As shown in a and b;

[0051] NTR testing flowchart based on the conduction method:

[0052] Figure 2 Figure a shows the test system for the conduction method, which includes NS, SA, test cables, and the required RF converter. The two are connected by a coaxial cable, forming a complete system. Figure 2 The test system.

[0053] The Y factor of the system is measured by turning the noise source on / off, and is denoted as Y1. It can be expressed by formula (9).

[0054]

[0055] in The noise temperature of the noise source when it is turned on; T represents the noise temperature of the noise source when it is in the off state, i.e., the physical temperature of the noise source during the test; Instr The internal noise temperature of SA; where It can be obtained from the excess noise ratio (ENR) of the noise source according to equation (10).

[0056]

[0057] According to equations (9) and (10), the instrument's own T can be obtained. Instr The device refers to SA, as shown in formula (7).

[0058]

[0059] Figure 2 Figure b shows the test system for the conduction method, which includes the NS, SA, test cables, the required RF converter, and the device under test (DUT). The DUT input is connected to the NS, and the DUT output is connected to the VSA. Together, these three components constitute the test system. Figure 2 (b) test system.

[0060] Figure 2 The NT value obtained from the measurement in Figure b can be regarded as the noise temperature T of the device itself. Instr T with the instrument under test DUT The composition is as shown in formula (12).

[0061]

[0062] The testing steps include:

[0063] a) according to Figure 2 (a) Set up the system and set various parameters in the spectrum analyzer, such as frequency, intermediate frequency bandwidth, preamplifier, temperature, and ENR (based on the ENR value of the noise source used during the test), according to the test requirements, and then conduct noise tests.

[0064] b) Using equation (11), the instrument can automatically calibrate the ENR value of the noise source, and the instrument can automatically measure the noise temperature T of the instrument itself. Instr .

[0065] c) According to Figure 2 (b) Set up the test system. The parameters of the spectrum analyzer are exactly the same as in step a). The overall noise temperature T of the test system can be measured. sys and the gain G of the DUT DUT ;

[0066] d) The noise temperature T of the DUT can be calculated according to equation (12). DUT .

[0067] This embodiment provides a noise temperature testing method suitable for OTA testing, comprising the following steps:

[0068] a) Build as Figure 1 The first test system shown in figure a, Figure 1 'a' represents instrument calibration.

[0069] In a preferred embodiment, the first test system includes a first noise source NS, a first spectrum analyzer SA, and a required RF adapter. The first noise source is connected to the first spectrum analyzer via a test cable and the RF adapter. The spectrum analyzer is configured with parameters such as frequency, intermediate frequency bandwidth, preamplifier, temperature, and ENR (based on the ENR value of the noise source used during testing) according to the test requirements. Noise testing is then performed, and the noise temperature T of the instrument itself can be measured. Instr :

[0070]

[0071] Among them, T Instr and Y Instr These are the noise temperature and Y-factor of the first test system, respectively. and These are the noise temperatures of the first noise source when it is on and off, respectively.

[0072] b) According to Figure 1 b is equipped with a second test system for reference antenna noise testing. The spectrum analyzer settings are exactly the same as in step a). The second system includes a second noise source, a second spectrum analyzer, two standard gain antennas with identical performance parameters, and the required RF adapter. The distance between the two reference antennas (i.e., the standard gain antennas) is D. The overall noise temperature T of the second test system can be measured. b The overall gain G of the second test system b ;

[0073]

[0074]

[0075] The noise temperature T of a single standard gain antenna can be obtained from the above formula. ANT and gain G ANT T ANT and G ANT This includes path loss in space.

[0076] c) Construct and test the third test system. The third test system includes a third noise source, a reference antenna, a device under test (DUT), test cables, a third spectrum analyzer, and the necessary RF adapters. The spectrum analyzer settings are identical to those in step a). The distance between the reference antenna and the antenna of the DUT is also D. Select the appropriate test system based on whether the DUT is a receiver or transmitter module. If the DUT is a receiver module, then proceed as follows: Figure 1 The third test system is equipped with a DUT (Device Under Test) for over-the-air noise testing when the DUT is the receiving module. The overall noise temperature T of the third test system can be measured. a and the overall gain G of the system a The noise temperature T of the device under test can be obtained according to the following formula. DUT,RX :

[0077]

[0078] In the formula, T a and G a For the noise temperature value and gain of the third test system, T Instr The noise temperature of the first test system; T b and G b For the noise temperature and gain of the second test system; G ANT The gain of a single standard gain antenna for the second test system.

[0079] If the device under test is a transmitting module, then according to Figure 1 The third test system is equipped with DUT (Device Under Test) for over-the-air noise testing of the transmitting module. The spectrum analyzer settings are exactly the same as in step a), and the distance between the reference antenna and the antenna of the device under test is also D. The overall noise temperature T of the third test system can be measured. c and the overall gain G of the system c The noise temperature T of the device under test DUT,TX :

[0080]

[0081] In the formula, T c and G c For the noise temperature value and gain of the third test system, T Instr The noise temperature of the first test system; T b and G b For the noise temperature and gain of the second test system; G ANT The gain of a single standard gain antenna for the second test system.

[0082] In another preferred embodiment, the device under test is a microwave / millimeter-wave module, receiver, transmitter, packaged antenna, or other devices and systems.

[0083] A specific test case using Keysight's SystemVue 2020 software is provided to demonstrate the rationality of the testing principle of this invention. For example... Figure 3a As shown in the figure, the leftmost PORT=1 port serves as a noise source, generating a 30dBm continuous wave at 27GHz; the rightmost PORT=2 port serves as the input terminal of the signal (spectrum) analyzer; the middle AntPath_1 is a pair of standard gain antennas with identical parameters, and the parameters are set according to the following formula. The total gain of this antenna is -40dB, the system noise figure is 40dB, and the system noise temperature is 2899719K (when T0=290K), as shown in the figure below.

[0084] Total Loss = Lossb + [Lossa * log 10 (DIST)]-G1-G2+Loss1+Loss2

[0085] In the formula, G1 and G2 are the gains of a single reference antenna (this gain does not include path loss in the air), Loss1 and Loss2 are the losses of the antenna material itself, and Lossb is the path loss. In this case, the spectrum (signal) analyzer can be considered an ideal (noise-free) instrument, i.e., T... Instr =0; through the corresponding formulas above and The noise temperature T of a single reference antenna can be obtained. ANT =28710K and gain G ANT =0.01dB.

[0086] Furthermore, such as Figure 3c As shown, the leftmost PORT=1 is the noise source, the rightmost PORT=2 is the input terminal of the signal analyzer, and the middle AntPath_1 is a pair of standard gain antennas with identical parameters. Figure 3a As in the diagram, Lin represents a linear gain amplifier. The simulation measures the noise temperature of the device under test (DUT). In this system, the DUT includes a receiving antenna and a linear gain amplifier with a noise figure of 3dB and a gain of 20dB.

[0087] The simulation results show that the noise temperature of the system is 5785970.7134K (when T0 = 290K). Using the corresponding formulas, the noise temperature of the DUT can be calculated to be 57572.607134K. When the gain of the antenna under test in the DUT is known (0.01 in the figure), the noise temperature T of the linear gain amplifier can be calculated using the following formula. LNA =288.626K, at which point the noise figure NF LNAThe value can be obtained from the following formula, which is 3dB. This result is consistent with the designed parameter values, thus verifying the feasibility of the test plan.

[0088] T LNA =(T DUT -T ANT2 )×G ANT2

[0089]

[0090] To further verify the feasibility of the test method proposed in this invention, actual measurement data based on this method are presented in Table 1.

[0091] Table 1 Noise and temperature test data based on the OTA method proposed in this invention.

[0092]

[0093] The test results are compared with those of the traditional conduction method, as shown in Table 2.

[0094] Table 2 Comparison of noise temperature test results between the OTA method and the traditional conduction method

[0095]

[0096] The active RF module uses a wideband low-noise amplifier module from Qotana, with a gain of 43dB and a saturation power Psat of 20dBm. The horn antenna is from A-INFO, with an average gain of 4.90–7.05GHz over a 10dBi frequency range. The noise source is an NC346V from Noise, which operates from 0.10GHz to 55.0GHz. A spectrum analyzer FSW43 from Rohde & Schwarz was selected as the signal receiver for this measurement, and a 28V DC power supply was provided to the noise source.

[0097] In Table 2, T Moudle,CT and T Moudle,OTA The results show the noise and temperature test results of the RF module based on the conduction method and the OTA method proposed in this invention, respectively. According to the comparison results, when the distance between the reference antenna and the device under test is 55cm, 75cm, and 95cm, the average error of the OTA method is 11.287%, 12.736%, and 12.32%, respectively, thus demonstrating the feasibility of this method.

[0098] This invention can test the noise temperature of devices under test (DUTs), including / excluding those with input and output ports. The test method is based on a pair of standard gain horn antennas, and in the open-circuit method, the horizontal distance between the transmitting and receiving antennas should ideally meet the far-field distance requirement. The test instruments required can be a combination of a noise source and a signal (spectrum) analyzer, or other noise-generating devices and receiving systems. Applicable DUTs include microwave and millimeter-wave modules, receivers, transmitters, packaged antennas, and other devices and systems. Before testing the noise temperature, calibration is required to address influencing factors such as ambient temperature and instrument noise, thereby improving the accuracy and reliability of the measurement.

[0099] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A noise temperature testing method suitable for OTA testing, characterized in that, Includes the following steps: a) Obtain the noise temperature of the instrument based on the first test system; The first test system includes a first noise source NS, a first spectrum analyzer SA, and the required RF adapter. The first noise source is connected to the first spectrum analyzer via a test cable and the RF adapter. The frequency, intermediate frequency bandwidth, preamplifier, temperature, and ENR parameters in the first spectrum analyzer are set according to test requirements. The noise temperature of the first noise source when it is on and off is obtained. , The Y factor of the system; The noise temperature of the instrument T Instr Calculated using the following formula: (1) in, T Instr and Y Instr These are the noise temperature and Y-factor of the first test system, respectively. and These are the noise temperatures of the first noise source when it is on and off, respectively. b) Construct a second test system and test the noise temperature and gain of the entire second test system; The second system includes a second noise source, a second spectrum analyzer, two standard gain antennas with identical performance parameters, and the required radio frequency adapter. The distance between the two standard gain antennas is D. Noise and temperature of the second test system T b Calculated using the following formula: （2） In the formula, T ANT The noise temperature of a single standard gain antenna. G ANT The gain of a single standard gain antenna, where T ANT and G ANT Including path loss in space; T Instr The noise temperature of the first test system; G b The gain of the second test system; c) Construct a third test system and test the noise temperature and gain of the entire third test system; The third test system includes a third noise source, a reference antenna, a device under test (DUT), test cables, a third spectrum analyzer, and the required RF adapters. The distance between the reference antenna and the DUT is D. The device under test DUT is an antenna integrated with a radio frequency module or a separate antenna to be tested; when the device under test DUT is a receiving module, the noise temperature T of the device under test DUT DUT,RX : （3） In the formula, T a and G a The noise temperature and gain of the third test system. T Instr The noise temperature of the first test system; T b and The noise temperature and gain of the second test system; The gain of a single standard gain antenna in the second test system; When the device under test (DUT) is a transmitter module, the noise temperature T of the DUT is... DUT,TX : （4） In the formula, T c and G c The noise temperature and gain of the third test system. T Instr The noise temperature of the first test system; T b and The noise temperature and gain of the second test system; The gain of a single standard gain antenna for the second test system.

2. The noise temperature testing method suitable for OTA testing according to claim 1, characterized in that, The device under test (DUT) includes a microwave / millimeter-wave module, a receiver, a transmitter, and a packaged antenna.

Images