SBOU266B september   2021  – august 2023 TRF1208

 

  1.   1
  2.    TRF1208 Evaluation Module
  3.   Trademarks
  4. 1Description
    1. 1.1 Features
    2. 1.2 General Usage Information
  5. 2EVM Overview
    1. 2.1 Schematic
    2. 2.2 PCB Layers
    3. 2.3 TRF1208 EVM Bill of Material
    4. 2.4 Stack-Up and Material
  6. 3Test Setup Diagrams
    1. 3.1 S-Parameter Test Setup
    2. 3.2 Noise Figure Test Setup
    3. 3.3 Two-Tone OIP3 Test Setup
  7. 4Related Documentation
  8. 5Revision History

3.3 Two-Tone OIP3 Test Setup

GUID-20210809-CA0I-XGC0-JBW7-TJMCNGV2FGR6-low.svgFigure 3-4 OIP3 Test Setup

Use the following guidelines for two-tone OIP3 measurement:

  1. As Figure 3-4 shows, combine two signal generator outputs using an in-phase power splitter and combiner. A 6-dB attenuator is recommended at the signal generator outputs to prevent the generators from talking to each other and resulting in signal generator IMD3 spurs.
  2. Set both the signal generator outputs to a power level and frequency spacing so that the signal generator yields the desired output power (POUT) at the device.
  3. TI recommends that the output power level is within the linear operation range of the TRF1208 device. For example, if the total desired output power at the device is 8 dBm, then set the signal generators such that each of the fundamental output power results in 2 dBm per tone. As a general rule, TI recommends to keep the total output power level approximately 6 to 8 dB lower than the 1-dB compression point. See the device data sheet for the output power levels supported by the device.
  4. For the OIP3 test, the two tones can be spaced by the specified frequency.
  5. Set the spectrum analyzer attenuation setting appropriately so that the spectrum analyzer non-linearity does not affect the measurements.
  6. Keep spectrum analyzer RBW and VBW settings identical for main tone and IM3 products.
  7. For output IP3 calculation, take into account combined losses at the desired frequency band between the TRF1208 device output to the spectrum analyzer input. The combined power loss is due to PCB output trace, RF coax cable, 0/180◦passive balun, and any attenuator pad used for external matching purposes. The calculated OIP3 is given in Equation .
    Output IP3 = (PIN_SA – IMD3) / 2 + PIN_SA + PLOSS

    where,

    • PIN_SA = Input power per tone into the spectrum analyzer
    • PLOSS = Power loss from the device output to the spectrum analyzer input
    • IMD3 = Higher power of the two intermodulation distortion products recorded at either 2f1 – f2 or 2f2 – f1
  8. In Equation , PIN_SA + PLOSS = POUT is the amplifier output power per tone.