Envelope tracking radio frequency front-end circuit
An envelope tracking (ET) radio frequency (RF) front-end circuit is provided. The ET RF front-end circuit includes an ET integrated circuit(s) (ETIC(s)), a local transceiver circuit, a target voltage circuit(s), and a number of power amplifiers. The local transceiver circuit receives an input signal(s) from a coupled baseband transceiver and generates a number of RF signals. The target voltage circuit(s) generates a time-variant ET target voltage(s) based on the input signal(s). The ETIC(s) generates multiple ET voltages based on the time-variant ET target voltage(s). The power amplifiers amplify the RF signals based on the ET voltages. Given that the time-variant ET target voltage(s) is generated inside the self-contained ET RF front-end circuit, it is possible to reduce distortion in the time-variant ET target voltage(s), thus helping to improve operating efficiency of the power amplifiers, especially when the RF signals are modulated with a higher modulation bandwidth (e.g., ≥200 MHz).
1. An envelope tracking (ET) radio frequency (RF) front-end circuit comprising:
an ET integrated circuit (ETIC) configured to generate a plurality of first ET voltages and a second ET voltage based on a time-variant ET target voltage;
a target voltage circuit configured to generate the time-variant ET target voltage based on an input signal;
a local transceiver circuit configured to generate a plurality of RF signals based on the input signal; and
a plurality of power amplifiers coupled to a plurality of antenna ports, respectively, each of the plurality of power amplifiers comprising:
a driver stage amplifier configured to amplify a respective one of the plurality of RF signals based on the second ET voltage; and
one or more output stage amplifiers coupled between the driver stage amplifier and a respective one of the plurality of antenna ports, the one or more output stage amplifiers configured to further amplify the respective one of the plurality of RF signals based on a respective one of the plurality of first ET voltages.
2. The ET RF front-end circuit of claim 1 wherein the local transceiver circuit is further configured to:
receive the input signal in an intermediate frequency (IF) from a coupled baseband transceiver circuit;
convert the input signal into the plurality of RF signals in an RF frequency higher than the IF; and
output the plurality of RF signals in a plurality of phase offsets, respectively.
3. The ET RF front-end circuit of claim 1 further comprising a plurality of second power amplifiers coupled to a plurality of second antenna ports, respectively, wherein:
the local transceiver circuit is further configured to generate a plurality of second RF signals based on the input signal; and
each of the plurality of second power amplifiers comprises:
a second driver stage amplifier configured to amplify a respective one of the plurality of second RF signals based on the second ET voltage; and
one or more second output stage amplifiers coupled between the second driver stage amplifier and a respective one of the plurality of second antenna ports, the one or more second output stage amplifiers configured to further amplify the respective one of the plurality of second RF signals based on a respective one of the plurality of first ET voltages.
4. The ET RF front-end circuit of claim 1 wherein the target voltage circuit comprises:
an amplitude detection circuit configured to detect a plurality of time-variant amplitudes of the input signal; and
an analog lookup table (LUT) configured to generate the time-variant ET target voltage based on the plurality of time-variant amplitudes.
5. The ET RF front-end circuit of claim 4 wherein the amplitude detection circuit comprises:
a positive detection circuit coupled between a signal input and a positive signal output, the positive detection circuit comprising:
a plurality of first signal branches disposed in parallel and each configured to shift the input signal by a respective one of a plurality of predefined phases; and
a first resistor-capacitor (RC) circuit configured to output, via the positive signal output, a plurality of positive amplitudes among the plurality of time-variant amplitudes that is detected across the plurality of predefined phases; and
a negative detection circuit coupled between the signal input and a negative signal output, the negative detection circuit comprising:
a plurality of second signal branches disposed in parallel and each configured to shift the input signal by the respective one of the plurality of predefined phases; and
a second RC circuit configured to output, via the negative signal output, a plurality of negative amplitudes among the plurality of time-variant amplitudes that is detected across the plurality of predefined phases.
6. The ET RF front-end circuit of claim 5 wherein the analog LUT is further configured to generate the time-variant ET target voltage based on the plurality of positive amplitudes and the plurality of negative amplitudes received from the amplitude detection circuit.
7. The ET RF front-end circuit of claim 4 further comprising:
a coupling circuit coupled between the plurality of power amplifiers and the plurality of antenna ports, the coupling circuit configured to provide a feedback signal indicating an output power of any of the plurality of power amplifiers; and
a calibration circuit configured to calibrate the analog LUT based on the feedback signal.
8. The ET RF front-end circuit of claim 1 further comprising:
a second ETIC configured to generate a plurality of third ET voltages and a fourth ET voltage based on a second time-variant ET target voltage;
a second target voltage circuit configured to generate the second time-variant ET target voltage based on a second input signal, wherein the local transceiver circuit is further configured to generate a plurality of second RF signals based on the second input signal; and
a plurality of second power amplifiers coupled to a plurality of second antenna ports, respectively, each of the plurality of second power amplifiers comprising:
a second driver stage amplifier configured to amplify a respective one of the plurality of second RF signals based on the fourth ET voltage; and
one or more second output stage amplifiers coupled between the second driver stage amplifier and a respective one of the plurality of second antenna ports, the one or more second output stage amplifiers configured to further amplify the respective one of the plurality of second RF signals based on a respective one of the plurality of third ET voltages.
9. The ET RF front-end circuit of claim 8 wherein the local transceiver circuit is further configured to:
receive the second input signal in the IF from a coupled baseband transceiver circuit;
convert the second input signal into the plurality of second RF signals in the RF frequency higher than the IF; and
output the plurality of second RF signals in a plurality of second phase offsets, respectively.
10. The ET RF front-end circuit of claim 8 wherein the second target voltage circuit comprises:
a second amplitude detection circuit configured to detect a plurality of second time-variant amplitudes of the second input signal; and
a second analog LUT configured to generate the second time-variant ET target voltage based on the plurality of second time-variant amplitudes.
11. The ET RF front-end circuit of claim 10 further comprising:
a second coupling circuit coupled between the plurality of second power amplifiers and the plurality of second antenna ports, the second coupling circuit configured to provide a second feedback signal indicating an output power of any of the plurality of second power amplifiers; and
a second calibration circuit configured to calibrate the second analog LUT based on the second feedback signal.
12. A wireless device comprising:
a plurality of envelope tracking (ET) radio frequency (RF) front-end circuits each comprising:
an ET integrated circuit (ETIC) configured to generate a plurality of first ET voltages and a second ET voltage based on a time-variant ET target voltage;
a target voltage circuit configured to generate the time-variant ET target voltage based on an input signal;
a local transceiver circuit configured to generate a plurality of RF signals based on the input signal; and
a plurality of power amplifiers coupled to a plurality of antenna ports, respectively, each of the plurality of power amplifiers comprising:
a driver stage amplifier configured to amplify a respective one of the plurality of RF signals based on the second ET voltage; and
one or more output stage amplifiers coupled between the driver stage amplifier and a respective one of the plurality of antenna ports, the one or more output stage amplifiers configured to further amplify the respective one of the plurality of RF signals based on a respective one of the plurality of first ET voltages.
13. The wireless device of claim 12 wherein the local transceiver circuit is further configured to:
receive the input signal in an intermediate frequency (IF) from a coupled baseband transceiver circuit;
convert the input signal into the plurality of RF signals in an RF frequency higher than the IF; and
output the plurality of RF signals in a plurality of phase offsets, respectively.
14. The wireless device of claim 12 wherein the ET RF front-end circuit further comprises a plurality of second power amplifiers coupled to a plurality of second antenna ports, respectively, wherein:
the local transceiver circuit is further configured to generate a plurality of second RF signals based on the input signal; and
each of the plurality of second power amplifiers comprises:
a second driver stage amplifier configured to amplify a respective one of the plurality of second RF signals based on the second ET voltage; and
one or more second output stage amplifiers coupled between the second driver stage amplifier and a respective one of the plurality of second antenna ports, the one or more second output stage amplifiers configured to further amplify the respective one of the plurality of second RF signals based on a respective one of the plurality of first ET voltages.
15. The wireless device of claim 12 wherein the target voltage circuit comprises:
an amplitude detection circuit configured to detect a plurality of time-variant amplitudes of the input signal; and
an analog lookup table (LUT) configured to generate the time-variant ET target voltage based on the plurality of time-variant amplitudes.
16. The wireless device of claim 15 wherein each of the plurality of ET RF front-end circuits further comprises:
a coupling circuit coupled between the plurality of power amplifiers and the plurality of antenna ports, the coupling circuit configured to provide a feedback signal indicating an output power of any of the plurality of power amplifiers; and
a calibration circuit configured to calibrate the analog LUT based on the feedback signal.
17. The wireless device of claim 12 wherein each of the plurality of ET RF front-end circuits further comprises:
a second ETIC configured to generate a plurality of third ET voltages and a fourth ET voltage based on a second time-variant ET target voltage;
a second target voltage circuit configured to generate the second time-variant ET target voltage based on a second input signal, wherein the local transceiver circuit is further configured to generate a plurality of second RF signals based on the second input signal; and
a plurality of second power amplifiers coupled to a plurality of second antenna ports, respectively, each of the plurality of second power amplifiers comprising:
a second driver stage amplifier configured to amplify a respective one of the plurality of second RF signals based on the fourth ET voltage; and
one or more second output stage amplifiers coupled between the second driver stage amplifier and a respective one of the plurality of second antenna ports, the one or more second output stage amplifiers configured to further amplify the respective one of the plurality of second RF signals based on a respective one of the plurality of third ET voltages.
18. The wireless device of claim 17 wherein the local transceiver circuit is further configured to:
receive the second input signal in the IF from a coupled baseband transceiver circuit;
convert the second input signal into the plurality of second RF signals in the RF frequency higher than the IF; and
output the plurality of second RF signals in a plurality of second phase offsets, respectively.
19. The wireless device of claim 17 wherein the second target voltage circuit comprises:
a second amplitude detection circuit configured to detect a plurality of second time-variant amplitudes of the second input signal; and
a second analog LUT configured to generate the second time-variant ET target voltage based on the plurality of second time-variant amplitudes.
20. The wireless device of claim 19 wherein each of the plurality of ET RF front-end circuits further comprises:
a second coupling circuit coupled between the plurality of second power amplifiers and the plurality of second antenna ports, the second coupling circuit configured to provide a second feedback signal indicating an output power of any of the plurality of second power amplifiers; and
a second calibration circuit configured to calibrate the second analog LUT based on the second feedback signal.