Table Of Contents

LO Sharing

Last Modified: November 5, 2018

You can configure the PXIe-3620 RF Upconverter and Downconverter Module module to use an external local oscillator (LO) signal when preparing the signal for upconversion or downconversion.

You can configure the PXIe-3620 to use internal or external LOs, but the module uses internal LOs by default. The LOs have the following uses:

  • LO1—LO source for the mmWave radio head.
  • LO2—Upconverts an in-phase/quadrature (I/Q) baseband signal to an intermediate frequency (IF) signal, and downconverts from an IF signal to an I/Q baseband signal, as shown in the following figure.
    spd-note-note
    Note  

    When simultaneously using the transmit and receive channels, the IF frequencies for receiving and transmitting will be the same.

Figure 1. PXIe-3620 Block Diagram
Devices LO Injection RF Frequency Formulas
mmRH-3602/3642/3652 mmWave Radio Heads High-side RF Frequency = LO Frequency - IF Frequency
  • LO Frequency = LO1 Frequency × 4
  • IF Frequency = LO2 Frequency × 3
mmRH-3603/3643/3653 mmWave Radio Heads Low-side RF Frequency = LO Frequency + IF Frequency
  • LO Frequency = LO1 Frequency × 3
  • IF Frequency = LO2 Frequency × 3
mmRH-3647/3657 mmWave Radio Heads Low-side RF Frequency = LO Frequency + IF Frequency
  • LO Frequency = LO1 Frequency × 8
  • IF Frequency = LO2 Frequency × 3

The following table shows a variety of examples of resultant LO frequencies for desired RF frequencies.

Table 1. Example Frequencies
mmWave Radio Heads Mode RF Frequency IF Frequency LO1 Frequency LO2 Frequency
Any/none IF only 11 GHz 3.667 GHz
mmRH-3602/3642/3652 mmWave 28.5 GHz 10.56 GHz 9.765 GHz 3.52 GHz (default)
mmRH-3603/3643/3653 mmWave 40 GHz 10.56 GHz 9.813 GHz 3.52 GHz (default)
mmRH-3647/3657 mmWave 73 GHz 12 GHz 7.625 GHz 4 GHz (default)

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