2G support for 2G and 3G/4G envelope tracking modulator
There is provided an amplification stage including an envelope tracking modulated supply for tracking a reference signal, comprising a low frequency path for tracking low frequency variations in the reference signal and for providing a first output voltage, and a high frequency path for tracking high frequency variations in the reference signal and for providing a second output voltage, and a combiner for combining the first and second output voltages to provide a third output voltage, the amplification stage further comprising a first amplifier arranged to receive the first output voltage as a supply voltage, and a second amplifier arranged to receive the third output voltage as a supply voltage, wherein the first and second amplifiers are enabled in different modes of operation.
1. An amplification stage including an envelope tracking modulated supply for tracking a reference signal, comprising:
a low frequency path for tracking low frequency variations in the reference signal and for providing a first output voltage;
a full spectrum path for tracking the reference signal and for providing a second output voltage;
a combiner configured to combine the first and second output voltages to provide a third output voltage;
a first power amplifier configured to receive the first output voltage as a power supply voltage for the first power amplifier; and
a second power amplifier configured to receive the third output voltage as a power supply voltage, for the second power amplifier.
2. The amplification stage of claim 1 , wherein:
the first power amplifier is disabled and the second power amplifier is enabled in a first mode of operation for the amplification stage; and
the second power amplifier is disabled and the first power amplifier is enabled in a second mode of operation for the amplification stage.
3. The amplification stage of claim 1 , wherein the full spectrum path comprises a linear amplifier configured to amplify a version of the reference signal.
4. The amplification stage of claim 3 , wherein the linear amplifier is enabled/disabled when the second power amplifier is enabled/disabled.
5. The amplification stage of claim 3 , wherein the full spectrum path further comprises a feedback path from an output of the linear amplifier to an input of the linear amplifier.
6. The amplification stage of claim 3 , wherein the full spectrum path further comprises a capacitor coupled between an output of the linear amplifier and the combiner.
7. The amplification stage of claim 3 , wherein the full spectrum path further comprises a delay element coupled to an input of the linear amplifier.
8. The amplification stage of claim 1 , wherein the full spectrum path further comprises a voltage source coupled to an input of the linear amplifier and configured to introduce an offset voltage to the input of the linear amplifier.
9. The amplification stage of claim 1 , further comprising a switch configured to selectively connect a DC power supply with the first power amplifier, wherein if the switch is closed, the first power amplifier is configured to receive a DC voltage of the DC power supply as the power supply voltage for the first power amplifier.
10. The amplification stage of claim 1 , wherein:
the first power amplifier is a power amplifier for a 2G or EDGE mode of operation; and
the second power amplifier is a power amplifier for a 3G or 4G mode of operation.
11. An RF amplifier including the amplification stage of claim 1 .
12. A wireless communication system including the amplification stage of claim 1 .
13. A wireless mobile device including the amplification stage of claim 1 .
14. A method for providing power to multiple amplifiers in an amplification stage including an envelope tracking modulated supply for tracking a reference signal, the method comprising:
tracking low frequency variations in the reference signal with a low frequency path of the amplification stage to provide a first output voltage;
tracking the reference signal with a full spectrum path of the amplification stage to provide a second output voltage;
combining the first and second output voltages to provide a third output voltage;
powering a first power amplifier with the first output voltage; and
powering a second power amplifier with the third output voltage.
15. The method of claim 14 , further comprising in a first mode of operation for the amplification stage:
enabling the first power amplifier; and
disabling the second power amplifier.
16. The method of claim 15 , further comprising in a second mode of operation for the amplification stage:
disabling the first power amplifier; and
enabling the second power amplifier.
17. The method of claim 16 , wherein the first mode of operation comprises a 2G mode of operation and wherein the second mode of operation comprises a 3G/4G mode of operation.
18. The method of claim 14 , wherein tracking the reference signal with the full spectrum path of the amplification stage comprises amplifying a version of the reference signal.
19. The method of claim 14 , wherein tracking the reference signal with the full spectrum path comprises applying an offset voltage to a version of the reference signal.
20. The method of claim 14 , wherein tracking the reference signal with the full spectrum path comprises applying a delay to the reference signal.