Voltage control device

1. A voltage control device for controlling supply voltages of a power amplifier (PA), the voltage control device comprising:

a first processing circuit, configured to provide a first supply voltage to at least one driving stage amplifier of the PA, the first processing circuit comprising:

a low dropout (LDO) DC-DC converter, a buck DC-DC converter, a boost DC-DC converter or a buck boost DC-DC converter

a second processing circuit, configured to provide a second supply voltage to an output stage amplifier of the PA;

wherein the first supply voltage is generated according to an average-power-tracking (APT) mechanism related to an average power level of a radio frequency (RF) signal transmitted by the PA.

2. The voltage control device according to claim 1 , wherein the first processing circuit receives a fixed supply voltage from a power source and convert the fixed supply voltage to the first supply voltage according to the APT mechanism.

3. The voltage control device according to claim 1 , wherein the first supply voltage is provided to the at least one driving stage amplifier through a first supply port, the PA has a first equivalent capacitance which is internally parasitic in the PA, and the first equivalent capacitance is related to the first supply port.

4. The voltage control device according to claim 1 , wherein the second supply voltage is generated according to an envelope-tracking-supply-modulation (ETSM) mechanism related to an envelope of the voltage level of the RF signal transmitted by the PA.

5. The voltage control device according to claim 4 , wherein the second processing circuit comprises an analog differential amplifier, and the second supply voltage is an analog modulated supply voltage generated according to the ETSM mechanism.

6. The voltage control device according to claim 4 , wherein the second processing circuit comprises a mixed-signal circuit, and the second supply voltage is a digital modulated supply voltage generated according to the ETSM mechanism.

7. The voltage control device according to claim 1 , wherein the second supply voltage is provided to the output stage amplifier through a second supply port, the PA has a second equivalent capacitance which is internally parasitic in the PA, and the second equivalent capacitance is related to the second supply port.

8. The voltage control device according to claim 7 , wherein the second supply port is further related to a third equivalent capacitance, and the third equivalent capacitance is exterior to the PA.

9. The voltage control device according to claim 8 , wherein a connecting path between the second supply port and the second processing circuit has a fourth equivalent capacitance, and the second supply voltage has a signal bandwidth related to the sum of the second equivalent capacitance, the third equivalent capacitance and the fourth equivalent capacitance.

10. A power amplifying system, comprising:

a power amplifier, comprising:

at least one driving stage amplifier; and

an output stage amplifier;

a first processing circuit, configured to generate a first supply voltage according to an average-power-tracking (APT) mechanism, and provide the first supply voltage to the at least one driving stage amplifier, the first processing circuit comprising:

a low dropout (LDO) DC-DC converter, a buck DC-DC converter, a boost DC-DC converter or a buck boost DC-DC converter,

a second processing circuit, configured to generate a second supply voltage according to an envelope-tracking-supply-modulation (ETSM) mechanism, and provide the second supply voltage to the output stage amplifier.

11. The power amplifying system according to claim 10 , wherein the first supply voltage is related to an average power level of a radio frequency (RF) signal transmitted by the PA.

12. The power amplifying system according to claim 10 , further comprising:

a power source, configured to provide a fixed supply voltage to the first processing circuit;

wherein the first processing circuit converts the fixed supply voltage to the first supply voltage according to the APT mechanism.

13. The power amplifying system according to claim 10 , further comprising:

a first supply port, connected between the first processing circuit and the at least one driving stage amplifier to transmit the first supply voltage;

wherein the PA has a first equivalent capacitance which is internally parasitic in the PA, and the first equivalent capacitance is related to the first supply port.

14. The power amplifying system according to claim 10 , wherein the second supply voltage is related to an envelope of the voltage level of the RF signal transmitted by the PA.

15. The power amplifying system according to claim 14 , wherein the second supply voltage is an analog modulated supply voltage or a digital modulated supply voltage generated according to the ETSM mechanism.

16. The power amplifying system according to claim 10 , further comprising:

a second supply port, connected between the second processing circuit and the output stage amplifier to transmit the second supply voltage;

wherein the PA has a second equivalent capacitance which is internally parasitic in the PA, and the second equivalent capacitance is related to the second supply port.

17. The power amplifying system according to claim 16 , wherein the second supply port is further related to a third equivalent capacitance, and the third equivalent capacitance is exterior to the PA.

18. The power amplifying system according to claim 17 , further comprising:

a connecting path, connected between the second supply port and the second processing circuit, the connecting path has a fourth equivalent capacitance;

wherein the second supply voltage has a signal bandwidth related to the sum of the second equivalent capacitance, the third equivalent capacitance and the fourth equivalent capacitance.