SBOSA17 September   2024 TRF1305B1

ADVMIX  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics - TRF1305B1
    6. 6.6 Typical Characteristics - TRF1305B1
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Fully Differential RF Amplifier
      2. 7.3.2 Output Common-Mode Control
      3. 7.3.3 Internal Resistor Configuration
    4. 7.4 Device Functional Modes
      1. 7.4.1 MODE Pin
        1. 7.4.1.1 Input Common-Mode Extension
      2. 7.4.2 Power-Down Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Input and Output Interface Considerations
        1. 8.1.1.1 Single-Ended Input
        2. 8.1.1.2 Differential Input
        3. 8.1.1.3 DC Coupling Considerations
      2. 8.1.2 Gain Adjustment With External Resistors in a Differential Input Configuration
    2. 8.2 Typical Application
      1. 8.2.1 TRF1305x1 as ADC Driver in a Zero-IF Receiver
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
    3. 8.3 Power Supply Recommendations
      1. 8.3.1 Supply Voltages
      2. 8.3.2 Single-Supply Operation
      3. 8.3.3 Split-Supply Operation
      4. 8.3.4 Supply Decoupling
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
        1. 8.4.1.1 Thermal Considerations
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Receiving Notification of Documentation Updates
    3. 9.3 Support Resources
    4. 9.4 Trademarks
    5. 9.5 Electrostatic Discharge Caution
    6. 9.6 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

8.1.2 Gain Adjustment With External Resistors in a Differential Input Configuration

The TRF1305x1 allow minor gain adjustments by configuring the input external resistive network that is part of the differential input configuration. Figure 8-5 shows the external input network that comprises of a shunt resistor, RIN_SH, and two series input resistors, RIN_SER, connected to the input pins of the amplifier.

TRF1305B1 Gain Adjustment With External Resistor Network Figure 8-5 Gain Adjustment With External Resistor Network

Table 8-1 provides resistor configurations for a 100Ω differential source impedance.

Table 8-1 Resistor Table for RS = 100Ω
TRF1305B1
POWER GAIN (dB) RIN_SH (Ω) RIN_SER (Ω)
10 1000 25
9 408 30
8 267 35
7 204 41
6 169 47
5 146 54

Use external resistive attenuation network only for small gain adjustments because there is a dB-to-dB noise figure degradation with the resistive attenuators. Use an amplifier version that requires minimal attenuation for achieving the overall gain.

For example, to realize 10dB overall gain with RS = 100Ω differential, the two options are:

  1. TRF1305B1 with RIN_SH = 1000Ω and RIN_SER = 25Ω resistors
  2. TRF1305A1 with RIN_SH = 125Ω and RIN_SER = 49Ω resistors

Option 1 is recommended because the NF is better by approximately 3dB compared to option 2.