SNLU284 May   2020 LMH9135

 

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3.1 Single-Tone Measurement Test Setup

GUID-48073CD7-2381-4285-8403-7B18C1F5A1F7-low.gifFigure 3-1 Single-Tone Setup for Gain and Output P1dB (1-dB Compression Point)

Use the following guidelines for single-tone measurement:

  1. The input to the EVM is differential. Differential signal is generated from the single-ended output of the signal generator using an external passive balun such as shown in Figure 3-1. Use of at least 3-dB attenuator pads are recommended at the differential ports of the balun for better matching with the board.
  2. The differential signals are fed into connectors J2 and J4.
  3. The RF signal generator used must support 3.3-GHz to 4.2-GHz signal frequency for testing out the LMH9135 EVM.
  4. When measuring the EVM for single-tone distortion products, TI recommends using an RF band pass filter (not shown in Figure 3-1) between the signal source and the balun.
  5. The output of the EVM from connector J3 is fed to the spectrum analyzer. An attenuator pad of at least 3 dB is recommended at the output port of the EVM.
  6. Lastly, it is recommended to properly characterize and account for the insertion loss of RF coaxial (coax) cables, attenuator pads, and passive baluns to measure accurate gain and power levels for the device.