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Fig. 4. Conventional envelope tracking power supply circuit.
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Fig. 5. Operation of conventional circuit in Fig. 4 at initial state. Fig. 6. Steady-state operation of conventional circuit in Fig. 4. Fig. 7. Switching frequency with respect to h and L. Fig. 8. Simulation results for Fig. 4 where the envelope signal is a DC signal. Fig. 9. Simulation results for Fig. 4 where the envelope signal is a sine wave signal. Fig. 10. In the case that the input slope surpasses the slope of DC-DC converter output. Fig. 11. Proposed envelope-tracking circuit. Fig. 12. Switching method in the proposed circuit. Fig. 13. Operation waveforms when the input slew rate is low. Fig. 14. Operation waveforms when the input slew rate is high. Fig. 15. Input envelope signal used for simulation. Fig. 16. Simulation results for Fig. 11 where the input slew rate is varying as in Fig. 15. Fig. 17. Envelope-tracking power supply using DC-DC converter with PWM signal. Fig. 18. Current and PWM signal waveforms in Fig. 17. Fig. 19. Proposed multi-phase architecture. Fig. 20 Simulated current and PWM signal waveforms for Fig. 19. Fig. 21 Comparison of OpAmp currents in the single-phase and multi-phase architectures.
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