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RF建模入门

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Learn how to use theRF预算分析仪app to build a simple RF receiver and then create an RF Blockset™ Circuit Envelope multi-carrier model to perform simulation.

Build a Cascade (row vector) of RF Elements.

You can build and analyze an RF cascade by adding elements characterized by their data sheet specifications.

You can use theRF Budget Analyserapp and drag and drop new elements, or you can script the chain elements using MATLAB® commands. If you are not familiar with the syntax, you can start with app and generate a MATLAB script.

Add elements to your chain in the following order:

  • Filter specified by an S-parameters Touchstone file

  • Low Noise Amplifier (LNA)

  • 直接转换解调器

  • Baseband amplifier

元素（1）= nport（'sawfilterpassive.s2p'); elements(2) = amplifier(。。。'Name','lna',。。。'Gain',18,。。。'nf'，3，。。。'oip3',10); elements(3) = modulator(。。。'Name','Demod',。。。'Gain',10,。。。'nf'，6.4，。。。'oip3',36,。。。'lo',2.45e9,。。。“ converterType','下'); elements(4) = amplifier(。。。'Gain',20,。。。'nf'，11.3，。。。'oip3',42);

Inspect RF Budget Using RF Budget Analyzer App

构建rfbudget目的。MATLAB命令窗口动态显示预算分析结果。

b = rfbudget(。。。'Elements',elements,。。。'InputFrequency',2.45e9,。。。“可用输入功率”，-70，。。。“ signalbandwidth”,8e6)
b =带有属性的rfbudget：元素：[1x4 rf.internal.rfbudget.element] inputfrequency：2.45 GHz obleInputpoptor：-70 dbm signalbandwidth：8 MHz求解器：8 MHz求解器：FRIIS autoupdate：Friis autoupdate：Friis autoupdate：真实分析结果输出结果：（GHZ）[2.45 2.45 2.45 2.45 2.45 2.45 0.45 0 0.0 0]输出功率：（ DBM）[-73.04 -55.04 -45.04 -25.04] trandducergain ：（ db）[-3.044 14.96 24.96 44.96] NF ：（ db）[2.326 5.699 5.823 5.868 5.868][] IIP3 ：（ dbm）[INF -5.674 -5.782 -7.865] OIP3 ：（ DBM）[INF 10 19.89 37.81] SNR：（DB）[DB）[32.62 29.25 29.12 29.12 29.08]

Or you can visualize therfbudget使用MATLAB命令在应用中的对象show(b)。

Generate RF Blockset Model

Use the出口button in theRF预算分析仪app to create an RF Blockset model or:

exportRFBlockset(b) save_system(gcs,'model_1')

您可以将此模型用于多载波电路包络模拟。这Input Port/Output Port端口和Configuration块已正确设置，您可以复制该模型以供在任何其他Simulink®Testbench中使用。金宝app

  • 输入端口指定一个以2.45 GHz为中心的复杂动力波信号。

  • 这output ports terminate the cascade and extract the envelope centered at DC (0 Hz). The I and Q signals are real baseband signals.

  • 这configuration block runs the simulation for a total of eight simulation frequencies in order to capture the non linearity introduced by the demodulator and amplifiers.

  • 这simulation stop time in this case is set equal to0。这意味着模拟仅对模型进行静态分析（谐波平衡）。

观察并理解模型块：

  • 这S-parameter block describing the filter uses rational fitting in order to simulate frequency data in the time domain. Notice that at 2.45 GHz it introduces a phase rotation of approximately -58 degrees.

  • Both amplifiers specify IP3, but you can also specify IP2.

  • 这demodulator includes ideal channel selection filters. Additional impairments can be added such as LO leakage and I/Q imbalance.

Simulate the model to compare the output power values with theRF预算分析仪app values. Notice that due to the phase rotation introduced by the S-parameter block, the complex input signal is partly downconverted on the I and on the Q branch, and thus the output power on the two branches is different. For this reason, the gain and other specs of direct conversion receivers are measured at an arbitrary low frequency.

Generate Measurement Testbench

Use the出口button in theRF预算分析仪app to create a measurement testbench or:

ExportTestBench（b）save_system（GCS，'model_2')

为了测量增益，噪声图和OIP3使用RF测量单元对话框选择要验证的值。

观察并理解测试板块：

  • You can measure the output on the I or Q branches.

  • Measurements are done at an arbitrary low frequency

  • 测量是通过任意信号带宽在时间域中完成的

Run the following simulation:

  • Measure the gain (disable the noise for accurate measurements).

  • Measure the NF. Reduce the baseband bandwidth to 8e3 for narrowband measurements. In this way, the noise figure measurement is not affected by the filter selectivity.

  • 测量OIP3。保持较小的基带宽和禁用噪声以进行准确的测量。

On comparing, you will see that the values of gain, noise figure, and IP3 match the values in theRF预算分析仪app reported in the testbench.

See Also

RF预算分析仪|Using RF Blockset for the First Time|电源端口和信号电源测量|创建自定义RF模块模型