SLAAED5 june   2023 AFE11612-SEP , INA240-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 GaN Biasing
  9. 6 VDRAIN Switching Circuit
  10. 7 Controlled Gate Sequencing Circuit
  11. 8 VDRAIN Monitoring
  12. 9 IDQ Monitoring
  13. 10External Negative Power Supply Monitoring
  14. 11PA Temperature Monitoring
  15. 12Summary
  16. 13References

10 External Negative Power Supply Monitoring

GaN PAs can be damaged if the VGS potential increases to too high, resulting in PA saturation. If the VSS supply collapses (meaning it slews to 0 V), this condition can occur as the differential op-amp circuit requires a negative supply. Thus, it is critical to monitor the VSS supply for collapse events. Monitoring can be done using a simple resistor divider biased by an external reference voltage, such as 5 V used for the device analog supply, to scale the negative VSS supply voltage to the ADC input range. If the external 5-V supply were to collapse, this would shut down the AFE11612-SEP and therefore shut down the PA_ON circuit. A zener diode can be added for additional protection in case of the external 5-V supply collapsing.

GUID-20230608-SS0I-S4PD-MBCN-T2NPDC7CTNTD-low.svgFigure 10-1 VSS Monitor Circuit