SLAAED5A June   2023  – September 2025 AFE11612-SEP , OPA4H199-SEP

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 LDMOS and GaN Power Amplifier FET PA Basics
  5. 2 VGS Compensation
  6. 3 Sequencing
  7. 4 An Integrated PA Biasing Solution
  8. 5 Negative Biasing for GaN PAs
  9. 6 Fast Switching for TDD Applications
  10. 7 VDRAIN Switching Circuit
  11. 8 Controlled Gate-Sequencing Circuit
  12. 9 VDRAIN Monitoring
  13. 10External Negative Power Supply Monitoring
  14. 11PA Temperature Monitoring
  15. 12Summary
  16. 13References
  17. 14Revision History

9 VDRAIN Monitoring

It is important to monitor the VDRAIN voltage to ensure the PA Drain supply is operating at the expected voltage. This can be accomplished using the ADC in the AFE11612-SEP. A resistor divider is required to properly scale the VDRAIN voltage to the 5V ADC range. The impedance of the resistor divider must be limited, ideally under 10kΩ, to allow sufficient current to charge the sampling capacitor. An external capacitor (CFILT) of approximately 1nF is required to quickly charge the ADC sampling capacitor.

VDRAIN Monitor CircuitFigure 9-1 VDRAIN Monitor Circuit