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, 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 power amplifier arranged to receive the first output voltage as a supply voltage, and a second power 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.
2. The amplification stage of claim 1 wherein the high frequency path includes a linear amplifier, wherein the linear amplifier is enabled/disabled when the second power amplifier is enabled/disabled.
3. The amplification stage of claim 2 wherein there is provided a feedback path from an output of the linear amplifier to an input of the linear amplifier, such that the linear amplifier is configured to amplify a signal comprising the full spectrum of the frequencies in the reference signal.
4. The amplification stage of claim 1 wherein the first power amplifier is disabled when the second power amplifier is enabled.
5. The amplification stage of claim 1 wherein the second power amplifier is disabled when the first power amplifier is enabled.
6. The amplification stage of claim 1 further comprising means for determining the power in the low frequency path when the first power amplifier is enabled.
7. The amplification stage of claim 6 wherein a path to a DC supply voltage is enabled when the determined power exceeds a threshold.
8. The amplification stage of claim 7 wherein the supply to the first amplifier, when enabled, is arranged to selectively receive either the DC supply voltage or the first output voltage.
9. The amplification stage of claim 6 wherein a path to a DC supply voltage is enabled when the determined power is below a threshold.
10. The amplification stage of claim 1 wherein the first power amplifier is a power amplifier for a 2G or EDGE mode of operation.
11. The amplification stage of claim 1 wherein the second power amplifier is a power amplifier for a 3G or 4G mode of operation.
12. An RF amplifier including the amplification stage of claim 1 .
13. A wireless communication system including the amplification stage of claim 1 .
14. A wireless mobile device including the amplification stage of claim 1 .
15. A method for 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 comprising a supply voltage for a first amplifier, 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 comprising a supply voltage for a second amplifier, wherein the method comprises enabling one of the first and second output amplifiers in different modes of operation.
16. The method of claim 15 further comprising determining the power in the low frequency path, and enabling a path to a DC supply voltage when the determined power exceeds a threshold.
17. The method of claim 16 further comprising disabling the path to the DC supply voltage when the determined power is below the threshold.
18. The method of claim 16 wherein when the first output amplifier is enabled the supply voltage of the amplification stage is either the DC supply voltage or the first output voltage.
19. The method of claim 15 wherein when the second output amplifier is enabled the supply voltage of the amplification stage is the third output voltage.
20. The method of claim 15 wherein the amplification stage is capable of a 2G mode of operation when the first amplifier is enabled or 3G/4G mode of operation when the second amplifier is enabled.