A Simpler Way to Make Dynamic EVM measurements of Wideband RF Power Amplifiers

Video transcript

To maximize power efficiency, RF PAs must have fast turn-on and turn-off switching times. But a transient response can affect the preamble at the start of the packet and cause an imperfect channel estimate, and in turn produce worse modulation accuracy.

In this video, we’re going to look at how you can simplify dynamic Error Vector Magnitude measurements of wideband Wi-Fi power amplifiers by taking advantage of NI’s RF front end validation solution.

For our instrumentation, we have a source measure unit supplying DC power to the PA under test, and a vector signal transceiver for RF measurements. The vector signal generator applies a Wi-Fi 7 signal with 320 MHz of bandwidth and 4096-QAM to the power amplifier under test, operating in the new frequency band from 6 to 7 GHz. The output of the PA goes to the vector signal analyzer.

To drive the PA enable line, we’re using the digital port PFI 0 on the VST.

Here in the RFIC test software application, we configure the instruments, the measurement parameters, the waveform, and the type of triggering control for dynamic EVM measurements. Let’s select here dynamic EVM, and we’re going to let this application draw specific timing information based on the characteristics of the Wi-Fi burst. Alternatively, I can modify the timing to increase or reduce the time delta between the PA enable on/off signal and the burst, and the duty cycle.

Let me just run it with the automatically calculated timing and configure a power sweep to characterize the dynamic EVM performance of this PA across a power range.

With just a few settings, our RFIC validation bench produces dynamic EVM versus power results, without writing a single line of code.