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

6 Fast Switching for TDD Applications

Some PA biasing applications such as time division duplexing require fast on-off gate switching. Fast gate switching is achieved by using the a low resistance space-rated MUX and capacitive charge sharing.

Capacitive charge sharing is used to achieve fast output switching. Figure 6-1 shows suggested capacitance of input and output capacitors. The two input voltages have large capacitors, an the output must have a small capacitor. When the MUX switches, the input capacitor quickly charges the smaller output capacitor, giving the required fast switching.

Gate Switching Circuit Figure 6-1 Gate Switching Circuit