ECE1390 RF L1 - Wireless RX-TX Tasks.pdf

Wireless Receiver

ECE1390 RF L1 - Wireless RX-TX Tasks-1758149264756.png

Low Noise Amplifier

  • low power signal is sensed from an antenna by a transmission line
  • noise gain must be minimized during amplification
  • radiation resistance , antenna output , must be matched with input of amplifier

Mixer:

  • down-convert wanted signal from carrier by multiplying with a local oscillator

ECE1390 RF L1 - Wireless RX-TX Tasks-1758061545010.png

  • after down-conversion, signal is at and image is at
  • previous images and signals are overlapped
  • Hartley Architecture:
    1. mix signal with cosine and sine
    2. shift the sine by
    3. add both
    • image is inverted by sine multiplication and rejected by addition

Filter

  • a dedicated band pass filter requires very high Q () and must be tune-able
  • out-of-band blockers can be blocked with simple filter (SAW filter: low Q, non tune-able)
  • in-band blockers are filtered after down-conversion
    • tune-able with local oscillator
    • half the bandwidth needed for filter (low pass filter)

Wireless Transceiver

Cartesian
ECE1390 RF L1 - Wireless RX-TX Tasks-1758150738398.png

Polar
ECE1390 RF L1 - Wireless RX-TX Tasks-1758150753624.png

Power Amplifier

  • boost signal for transmission with high efficiency
  • input of matching network must be matched with output of amplifier

Mixer
ECE1390 RF L1 - Wireless RX-TX Tasks-1758150300150.png

  • Cartesian up-conversion for QAM
  • Polar up-conversion for FM

Filter

  • same issues as RX
  • closest replicas are filtered before up conversion
  • external filters for out-of-band