The RF source signal takes the following path from the PXIe-5644 front panel to the PXI Express controller.

  1. The RF signal is connected to the PXIe-5644RF IN front panel connector.
  2. If required by the gain configuration, the signal is attenuated by 10 dB fixed attenuation and applies 0 dB to 16 dB of variable attenuation in 1 dB steps.
  3. If required by the gain configuration, the preamplifier switches into the signal path. The signal is now amplified, which improves the noise figure.
  4. The signal is amplified or attenuated based on the reference level to the required mixer level. The amplification or attenuation helps avoid analog saturation and ADC overflow.
  5. The attenuated or amplified signal is mixed with the 0° phase and 90° phase LO signal at the tuned center frequency and then frequency-translated to DC.
  6. The frequency-translated signal is split into two analog channels, I and Q. The I and Q channels are 90° out-of-phase from each other.
  7. The analog-to-digital converter (ADC) converts the I and Q signals from the analog to the digital domain at a rate of 120 MS/s.
  8. The digital I and Q signals are now accessible through LabVIEW FPGA I/O nodes for further processing or transfer to the host computer.