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RF Circuit Design - [Ch4-2] LNA, PA, and Broadband Amplifier

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LNA, PA, and Broadband Amplifier

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RF Circuit Design - [Ch4-2] LNA, PA, and Broadband Amplifier

  1. 1. Chapter 4-2 Introduction to Low Noise, High Power, and Broadband Amplifier Design Chien-Jung Li Department of Electronics Engineering National Taipei University of Technology
  2. 2. Department of Electronic Engineering, NTUT Functional Block Diagram of Communication Systems Input Transducer Output Transducer Input Signal (Audio, Video, Data) Output Signal (Audio, Video, Data) Transmitter (Tx) Receiver (Rx) Channel • The main job of the communication systems is to transfer useful information from one end to the other ends. 2/16
  3. 3. Department of Electronic Engineering, NTUT Block Diagram of a Basic Radio System • Transmitter (Tx) • Receiver (Rx) Data in Modulator IF Filter Mixer Bandpass Filter (BPF) Power Amplifier (PA) Antenna Local Oscillator (LO) Bandpass Filter (BPF) Mixer IF Filter Data out DemodulatorIF Amplifier Local Oscillator (LO) Low Noise Amplifier (LNA) Antenna  This architecture was first called superheterodyne and patented in 1917 by Armstrong. The “transceiver” means the system that combines Tx and Rx. 3/16
  4. 4. Department of Electronic Engineering, NTUT Constant NF Circles 4/16
  5. 5. Department of Electronic Engineering, NTUT Noise Circle and Gain Circles (I) 5/16
  6. 6. Department of Electronic Engineering, NTUT Noise Circle and Gain Circles (II) 6/16
  7. 7. Department of Electronic Engineering, NTUT Noise Circle and Gain Circles (III) 7/16
  8. 8. Department of Electronic Engineering, NTUT Broadband Design • The most popular and well-established circuit techniques employed in the design of broadband amplifiers that are generalized in hybrid and monolithic technologies are:  Reactively matched circuit  Traveling wave distributed circuit  Feedback circuit  Lossy matched circuit 8/16
  9. 9. Department of Electronic Engineering, NTUT Broadband Stability 9/16
  10. 10. Department of Electronic Engineering, NTUT Broadband v.s. Narrowband Matching 10/16
  11. 11. Department of Electronic Engineering, NTUT PA Matching Considerations • In order to obtain maximum output power, typically the power amplifier is not conjugately matched. In stead, the load is designed such that the amplifier has the correct voltage and current to deliver the required power. 11/16
  12. 12. Department of Electronic Engineering, NTUT Matching to S22* vesus Matching to Γopt 12/16
  13. 13. Department of Electronic Engineering, NTUT Class A, AB, C PAs 13/16
  14. 14. Department of Electronic Engineering, NTUT Power Contour 14/16
  15. 15. Department of Electronic Engineering, NTUT Power Combing 15/16
  16. 16. Department of Electronic Engineering, NTUT Cascaded PA 16/16

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