解决普通混频器测量的技术难题

发布时间：2013-04-03 09:51:59 来源：文档文库

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解决普通混频器测量的技术难题

一、多端口测试系统可以同时实现高速度和高精度

A, multi-port test system can achieve high speed and high precision at the same time

　　传统vna使用一个作为激励的rf信号源，并采用多路测量接收机来测量正反两个方向上的入射、反射和传输信号；传统vna有两个测试端口，因为早期的大多数器件只有一个或两个端口。为了对多端口器件进行测量，就需要在被测器件(dut)的各个端口之间多次变换测试电缆和端接负载，直到完成对所有端口的测量。现在，rf系统所使用的许多器件都有三、四个端口，多至七、八个端口的器件也变得越来越常见。导致器件端口数量提高的原因有两个：一个是平衡元器件的广泛使用，另一个是子组件的集成程度不断提高，如当前手机中使用的前端模块。为此，可以考虑增加测试系统的测试端口数量进行放大器和混频器的测量。多端口测试系统与使用传统的两端口vna相比，大大地提高了测试速度。因为它有四大改进：

Traditional vna using a a rf signal source of motivation, and USES the multi-channel measurement receiver to measure the positive and negative two direction of incidence, reflection and transmission signal; Traditional port vna have two tests, because most of the early device with only one or two ports. In order to measure the multiport components, you need the device under test (dut) of each port test cable and terminal load between multiple transformation, until the complete measurement of all ports. Now, many devices used by the rf system have three or four ports, up to seven or eight port devices are becoming more common. Increased device port number by two reasons: one is the equilibrium components of widely used, the other one is a child component integration degree unceasing enhancement, such as front-end module used in the current mobile phone. To do this, you can consider increasing the number of test port test system for measuring amplifier and mixer. Multi-port test system compared with using the traditional two port vna, greatly improve the speed test. Because it has four big improvements:

　　（一）两个信号源

(a) two signal source

　　第二个内部信号源与第一个信号源的频率和功率电平设置是相互独立的。第二个信号源可用于非线性放大器测试如互调失真（imd），或用作测试混频器和变频器的快速本地振荡器（lo）。

Second internal signal source and the first frequency signal source and the power level Settings are independent of each other. Second source can be used in the nonlinear amplifier test such as the intermodulation distortion (imd), or used as a testing mixer and the local oscillator (lo) frequency converter.

　　（二）宽带信号合路器

(2) broadband signal combiner

　　内部信号合路器可以在仪器的相关测试端口耦合器之前将两个源合并在一起。这便简化了需要两个信号源的放大器测试设置。

Internal signal coupler combiner can in instrument related test port before the two source merged together. This simplifies the need two signal amplifier test setup.

　　（三）信号切换和接入点

(3) the signal switching and the access point

　　辅助开关和射频接入点能实现灵活的信号路径选择，并增加外部信号调理得硬件（如推动放大器）或外部测试设备（如数字信号发生器或矢量信号分析仪）。

Auxiliary switch signal and radio frequency access points can realize flexible routing, and increase the external signal conditioning hardware (such as driving amplifier) or external test equipment (such as a digital signal generator and vector signal analyzer).

　　（四）脉冲测试能力

(4) pulse testing capability

　　内部脉冲调制器和脉冲发生器提供完全一体化的脉冲s参数解决方案。

Internal pulse modulator and pulse s parameters of the pulse generator to provide fully integrated solutions.

　　这些改进简化了测试设置过程并在测量放大器、混频器和变频器时缩短了测试时间。这些新增加的特性结合在一起极大地扩大了对被测器件（dut）进行一次连接可以实现的测量范围。

These improvements to simplify the test setup and the measuring amplifier, mixer and frequency converter to shorten the test time. These new features together expanded enormously to the device under test (dut) can realize the measurement range of a connection.

　　二、内置两个rf信号源来简化放大器和混频器的测量

Second, the built-in two rf signal source to simplify the measurement of mixer and amplifier

　　新型vna的内部设置有两个内置rf信号源，可以对imd进行测量，而以前这主要通过两个外接的信号源和一个频谱分析仪来完成。基于vna的测试方法使得在测试过程中对仪表的设置更加简单、测量时间更短、准确性更高。内置两个rf信号源进行放大器和混频器的测量有三个优点。首先，只用一台测试仪器，乳化液泵站只进行一次连接便能对全部参数进行测量：s参数、增益压缩、输出谐波、imd等等。其次，与使用频谱分析仪相比，用功率计对vna进行校准之后，测量精度更高。最后，如果使用一台频谱分析仪和两个独立的信号源进行同样的测试，完成测试需要花几分钟的时间，但使用pna-x只需0.6秒。

New internal set has two built-in rf signal source of vna, the imd can be measured, and before this through two main external signal source and a spectrum analyzer. Test method based on vna made during testing on the installation of instrument is more simple, the measuring time is shorter, the accuracy is higher. Built-in two rf signal amplifier and mixer measurement has three advantages. First of all, just take a testing instrument, a connection can only for all parameters measured: s parameters, the gain compression and output harmonic, imd, and so on. Second, compared with using a spectrum analyzer, with the power meter to the vna calibration, measurement accuracy is higher. Finally, if you are using a spectrum analyzer and two independent signal source for the same test, complete the tests need to spend a few minutes, but use the pna - x just 0.6 seconds.

　　两个内置信号源的性能增强，简化了放大器和混频器测量。例如，测试端口可利用的最大信号功率通常为+13至+20 dbm（取决于型号和频率）。

Performance enhancements of the two built-in signal source, simplify the measuring amplifier and mixer. Test ports available maximum signal power, for example, usually to + 13 to + 20 DBM (depending on the type and frequency).

这对将放大器驱动到非线性区很有帮助，并且在把信号源用作测试混频器的lo信号时也经常要这样。这两个内置信号源的谐波成分也非常低（通常为–60 dbc 或更低），从而提高谐波和imd测量的精度，快速升柱器在表征放大器的特性时很容易就可以让放大器从线性工作范围转化到非线性工作范围。

This is very helpful to amplifier nonlinear area, and when the signal source used for testing the lo signal mixer are often to be like this. The harmonic components of the two built-in signal source is also very low (usually - 60 DBC or less), so as to improve the precision of harmonic and imd measurement, the characterization of the amplifier features can easily let amplifier from the linear scope of work into the nonlinear working range.

　　三、如何对放大器进行测量

Third, how to measure the amplifier

　　对于放大器的测量，可以使用信号合路器将两个信号合并，然后送到被测放大器（aut）的输入端。aut的非线性会引起与被放大的输入信号一道出现的互调分量。在通信系统中，这些多余的分量将进入工作频带且不能通过滤波去除。实践中，只测三阶分量，因为它们是造成系统性能下降的最重要因素。在扫描状态下进行放大器测试，一个值得注意的改变是对功率电平而不是对频率进行扫描，这有助于研发工程师们建立晶体管和放大器非线性行为模型。

For measuring amplifier, can be used to signal combiner, will merge two signals, and then sent to the amplifier under test (aut) of the input. Aut nonlinear causes together with input signal is amplified by the intermodulation components. In communication systems, these extra weight will enter the working frequency band and not through a filter to remove. In practice, only measuring the third-order component, because they are the most important factor to the decline in performance of the system. Amplifier under the state of scanning test, a notable change is the power level rather than on the frequency scan, which will help to research and development engineers transistor amplifier and nonlinear behaviour model is set up.

　　相位与驱动的关系是用pna-x很容易完成的另一种常见的双信号源测试。这个测试参数表征的是当在相邻通道或带外存在大信号时，放大器处理小信号的能力。测试的方法是把不同频率的一个大信号和一个小信号合在一起然后送至被测放大器（aut），然后在改变大信号的功率时（使用功率扫描），测量小信号的s21相位。

Phase relationship with the driver is using pna - x is very easy to do another common signal source to test. Characterization is when the test parameters in the adjacent channel, or when there is a large signal band's ability to handle small signal amplifier. Test method is to put the different frequencies of a signal and a small together and then send the signals to be amplifier (aut), and then in the large signal power is changed (using power scanning), measure the small signal of s21 phase.

　　另一种使用双信号源技术、在建立晶体管和放大器非线性行为模型时会用到的参数是“热态s参数”，这种测试方法用来表征在某一给定频率下，当存在一个比较大的偏离于s参数测试信号的另外一个输入信号，并且被测放大器的输出因为这个大信号的存在而产生压缩时，放大器小信号s参数的特性。在进行热态s参数测试时，注意不要让被测放大器输出的“热信号”超出了矢量网络分析仪测试接收机的损坏电平。

Another use double signal source technology, the transistor and the amplifier nonlinear behavior model is established by use of parameter is "hot" s parameters, the test method is used to characterize under a given frequency, when there is a big deviation in test signal s parameters of another input signal, and measured the output of the amplifier because of the existence of the large signal produced by compression, the characteristics of the amplifier small signal s parameter. In the hot s parameters test, pay attention to don't let the noise of the amplifier output signal "hot" beyond the vector network analyzer test receiver damage level.

　　四、nxn技术在混频器测试中的应用

Fourth, NXN technology in the mixer test application

　　混频器作为基本的频率变换器件，其主要测量参数有传输特性（变频损耗、相位、群延迟）、发射特性（驻波比、回波损耗、隔离度）、非线形（变频压缩、高阶混频产物、双音imd）等。

Mixer as basic frequency conversion device, its main measurement parameters transmission characteristics (loss of variable frequency, phase, group delay), emission characteristic (standing wave ratio, return loss, isolation degree) and nonlinear (frequency compression, high mixing product, dual imd), etc.

　　（一）常规测量法的主要缺点

(a) the main drawback of conventional measuring method

　　常规的测量方法主要采用“已知混频器”（golden piece）法。在这种方法中，测量获得的数据是与“已知混频器”（golden piece）的数据的相对值。这种方法在行业中已经被认为是频率变换器件测量的标准测量法。在测量中要用到两个混频器，一个的输出用于锁定vna，另一个用于测量。混频器常规测量法主要存在以下缺点：对于不同参数的测量仍然需要不同的连接方式；由于使用标准混频器golden piece进行校准，标准混频器golden piece的任何损耗或损害都会破坏原有的参考标准；不同来源的产品的比较是很困难的；不能对源和负载匹配的测量进行修正；与进行“s”参数测量的连接方式不同。

Conventional measuring method mainly adopts "known mixer" (golden piece) method. In this method, measuring data obtained with known "mixer" (golden piece) of the relative value of data. This approach has been considered a frequency conversion device in the industry standard measurement method. Want to use two mixer in the measurement, an output for locking vna, another for measurement. Mixer conventional measuring method mainly has the following disadvantages: for different parameter measurement still need different ways of connection; Due to the use of standard mixer golden piece for calibration, standard mixer golden piece for any loss or damage to undermine the original reference standard; Different sources of product comparison is difficult; Can't to modify source and load matching measure; Connection with "s" parameter measurement in a different way.

　　（二）混频器测量的nxn测量法

Mixer (2) the NXN measurement method

　　nxn测量法有效的解决了常规测量法所无法解决的一些困难和技术难点。nxn测量法，简单的说，它是基于混频器为互易器件的测量方法。其测量需要三个混频器，由于混频器1在两个方向上都需要进行测量，所以要求混频器1为双向混频器。由于需要滤出镜频信号，需要中频滤波器。该方法主要通过在校准时解三个方程求三个未知数，即通过三个三元一次方程得到唯一解的办法，然后将解出的参数代入对dut的测量得到一个一元一次方程并求出解。

NXN method effectively solves the conventional measurement method can solve some of the difficulties and technical difficulties. NXN measurements, in simple terms, it is based on the frequency mixer for reciprocity measurement device. Its measurement requires three mixer, due to the mixer 1 in both directions are need to measure, so asked mixer 1 for two-way mixer. Because of the need to filter out image frequency signal, need intermediate frequency filter. The method mainly through the school on time solve three equations for three unknowns, namely through three three yuan an equation to get the unique solution, and then will work out the parameters into the measurement of the dut to get a a yuan a equation and the solution.

　　混频器是最常见的变频器件，而变频器件的测量一直以来都相对困难和复杂。传统的测量方法包括使用功率计、频谱仪、标量网络分析仪、矢量网络分析仪等。上文主要阐述了nxn技术（也可以叫三混频器技术）在混频器测试中的应用，通过这种方法，可以实现实时的误差修正，同时测量连接方式简单，一次测量就可以得到所有的参数。nxn测量法最大的优点就是可以直接对混频器的幅度和相位进行测量，测量结果是绝对数据，不是相对数据，结果更准确；同时可以对系统误差进行误差校准，即12项误差，如频率响应、源匹配、负载匹配等，可以得到实时的12项误差校准数据。

Mixer is one of the most common inverter, the inverter measurement has been relatively difficult and complex. The traditional measurement methods include the use of power meter, spectrum analyzer, scalar network analyzer and vector network analyzer, etc. Above, mainly elaborated the NXN technology (can also be called three mixer technology) application in the mixer test, in this way, can realize real-time error correction, measurement simple connection mode at the same time, a measuring all the parameters can be calculated out. NXN measurement method of the biggest advantages is the ability to directly measure of amplitude and phase of mixer, the measurement result is absolute data, not relative data, the result more accurate; Error calibration of system errors may be at the same time, the error of 12 items, such as frequency response, such as the source, load match, can get real time 12 error calibration data.

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