SCBA020A October   1999  – March 2020 TMS3705

 

  1.   Integrated TIRIS™ RF Module TMS3705 Introduction to Low-Frequency Reader
    1.     Trademarks
    2. 1 Document Overview
    3. 2 Introduction
    4. 3 Key Features of the TMS3705
      1. 3.1 PLL for the System Clock
      2. 3.2 Ceramic Resonator for Reference Oscillator
      3. 3.3 Full-Bridge Driver Stage
      4. 3.4 Fully Integrated Bandpass Amplifier
      5. 3.5 Multifunctional 2-Wire Interface
    5. 4 Sequence Control
      1. 4.1 Initialization
    6. 5 Circuit Description of the Sample RF Module
      1. 5.1 Oscillator System
      2. 5.2 Antenna Circuit
      3. 5.3 Pre-Amplifier
      4. 5.4 Interface Circuit to the Control Module
      5. 5.5 Antenna Coil
    7. 6 Regulatory Notices and Ordering
      1. 6.1 Regulatory Notices
      2. 6.2 Ordering
  2.   Revision History

5.3 Pre-Amplifier

During receive phase, outputs ANT1 and ANT2 are held at GND. The built-in pre-amplifier operates as internal biased operational amplifier. The resistor ratio of R2/R1 determines the gain factor, which should not be greater than 5. If the gain is higher than 5, the amplifier output can reach its upper limiting area due to the internal DC biasing.