Power tracker for multiple transmit signals sent simultaneously
Techniques for generating a power tracking supply voltage for a circuit (e.g., a power amplifier) are disclosed. The circuit may process multiple transmit signals being sent simultaneously on multiple carriers at different frequencies. In one exemplary design, an apparatus includes a power tracker and a power supply generator. The power tracker determines a power tracking signal based on inphase (I) and quadrature (Q) components of a plurality of transmit signals being sent simultaneously. The power supply generator generates a power supply voltage based on the power tracking signal. The apparatus may further include a power amplifier (PA) that amplifies a modulated radio frequency (RF) signal based on the power supply voltage and provides an output RF signal.
1. An apparatus comprising:
a power tracker configured to determine an overall power of a plurality of transmit signals based on in-phase (I) and quadrature (Q) components of the plurality of transmit signals, and configured to determine a power tracking signal based on the overall power of the plurality of transmit signals, the plurality of transmit signals configured for simultaneous transmission from the apparatus on a plurality of carriers at different frequencies with carrier aggregation; and
a power supply generator configured to generate a power supply voltage based on the power tracking signal and to provide the power supply voltage to a power amplifier of the apparatus to produce an output radio frequency (RF) signal for the plurality of transmit signals.
2. The apparatus of claim 1 , further comprising a digital-to-analog converter configured to receive a digital power tracking signal from the power tracker and provide an analog power tracking signal to the power supply generator.
3. The apparatus of claim 1 , wherein the power amplifier is configured to receive an RF signal generated by a single transmit circuit based on the I and Q components of the plurality of transmit signals.
4. The apparatus of claim 1 , wherein the power amplifier is configured to receive an RF signal summed from a plurality of signals generated by respective transmit circuits based on respective I and Q components of the plurality of transmit signals.
5. The apparatus of claim 1 , wherein the plurality of transmit signals are configured for transmission with contiguous intra-band carrier aggregation.
6. The apparatus of claim 5 , wherein the power tracking signal has a bandwidth that is smaller than an overall bandwidth of the plurality of carriers.
7. The apparatus of claim 1 , wherein the power tracker is configured to determine the overall power based on the I and Q components of the plurality of transmit signals at baseband.
8. The apparatus of claim 1 , wherein the apparatus is included in a cellular phone, smartphone, tablet, or laptop computer.
9. The apparatus of claim 8 , wherein the cellular phone, smartphone, tablet, or laptop computer is configured to transmit the RF signal to a base station.
10. The apparatus of claim 1 , wherein the plurality of transmit signals comprise Single Carrier Frequency Division Multiple Access (SC-FDMA) signals.
11. The apparatus of claim 1 , wherein the overall power is a sum of powers of each of the transmit signals in a form of I 1 2 (t)+Q 1 2 (t)+ . . . +I K 2 (t)+Q K 2 (t), wherein I k 2 (t)+Q k 2 (t) denotes a power of the k-th transmit signal in sample period t.
12. The apparatus of claim 1 , the power supply generator comprising:
a power tracking amplifier configured to receive the power tracking signal and generate the power supply voltage.
13. The apparatus of claim 12 , the power supply generator further comprising:
a switcher configured to sense a first current from the power tracking amplifier and provide a second current for the power supply voltage based on the sensed first current.
14. A method comprising:
determining an overall power of a plurality of transmit signals based on in-phase (I) and quadrature (Q) components of the plurality of transmit signals, the plurality of transmit signals configured for transmission on a plurality of carriers at different frequencies with carrier aggregation;
determining a power tracking signal based on the overall power of the plurality of transmit signals;
generating a power supply voltage based on the power tracking signal; and
providing the power supply voltage to a power amplifier to produce an output radio frequency (RF) signal for the plurality of transmit signals.
15. The method of claim 14 , wherein the plurality of transmit signals are configured for transmission with contiguous intra-band carrier aggregation.
16. The method of claim 15 , wherein the power tracking signal has a bandwidth that is smaller than an overall bandwidth of the plurality of carriers.
17. The method of claim 14 , wherein the plurality of transmit signals comprise Single Carrier Frequency Division Multiple Access (SC-FDMA) signals.
18. The method of claim 14 , wherein the plurality of transmit signals are configured for transmission from a user equipment to a wireless communication system.
19. The method of claim 14 , wherein the overall power is a sum of powers of each of the transmit signals in a form of I 1 2 (t)+Q 1 2 (t)+ . . . +I K 2 (t)+Q K 2 (t), wherein I k 2 (t)+Q k 2 (t) denotes a power of the k-th transmit signal in sample period t.
20. A non-transitory computer-readable medium comprising instructions, that when executed by a processor, cause an apparatus to:
determine an overall power of a plurality of transmit signals based on in-phase (I) and quadrature (Q) components of the plurality of transmit signals, the plurality of transmit signals configured for transmission on a plurality of carriers at different frequencies with carrier aggregation;
determine a power tracking signal based on the overall power of the plurality of transmit signals;
generate a power supply voltage based on the power tracking signal; and
provide the power supply voltage to a power amplifier of the apparatus to produce an output radio frequency (RF) signal for the plurality of transmit signals.