Envelope tracking circuit
An envelope tracking (ET) circuit is provided. The ET circuit includes an amplifier array(s) configured to amplify a radio frequency (RF) signal(s) based on a first input voltage and a second input voltage. The ET circuit includes a pair of tracker circuits each configured to generate a modulated voltage. Control circuitry couples a selected tracker circuit among the tracker circuits to provide a selected modulated voltage (e.g., ET modulated voltage) to the amplifier array(s) as the first input voltage. Depending on usage scenarios, the control circuitry also provides an ET modulated voltage, an average power tracking (APT) modulated voltage, or a constant voltage to the amplifier array(s) as the second input voltage. As such, the ET circuit can support the RF signal(s) modulated in a wide range of modulation bandwidth without compromising efficiency and/or increasing heat dissipation of the amplifier array(s).
1. An envelope tracking (ET) circuit comprising:
an amplifier array comprising:
a first amplifier input configured to receive a first input voltage;
a second amplifier input configured to receive a second input voltage; and
a plurality of amplifier circuits comprising a plurality of output stage amplifiers coupled to the first amplifier input to receive the first input voltage and a plurality of driver stage amplifiers coupled to the second amplifier input to receive the second input voltage, the plurality of amplifier circuits configured to amplify a radio frequency (RF) signal based on the first input voltage and the second input voltage;
a first tracker circuit configured to generate a first modulated voltage;
a second tracker circuit configured to generate a second modulated voltage; and
control circuitry configured to:
couple a selected tracker circuit among the first tracker circuit and the second tracker circuit to the first amplifier input to provide a selected modulated voltage among the first modulated voltage and the second modulated voltage to the amplifier array as the first input voltage; and
provide a determined voltage to the amplifier array as the second input voltage.
2. The ET circuit of claim 1 further comprising switching circuitry coupled to the first tracker circuit, the second tracker circuit, the first amplifier input, and the second amplifier input, wherein the control circuitry is further configured to control the switching circuitry to couple the selected tracker circuit to the first amplifier input and to provide the determined voltage to the second amplifier input.
3. The ET circuit of claim 1 wherein the RF signal is modulated to a plurality of phase and amplitude terms prior to being amplified by the plurality of amplifier circuits.
4. The ET circuit of claim 3 wherein the amplifier array comprises:
a plurality of signal inputs configured to receive the RF signal in the plurality of phase and amplitude terms, respectively; and
a plurality of signal outputs configured to output the RF signal in the plurality of phase and amplitude terms, respectively.
5. The ET circuit of claim 4 wherein the plurality of amplifier circuits is provided in parallel between the plurality of signal inputs and the plurality of signal outputs, respectively.
6. The ET circuit of claim 5 wherein:
each of the plurality of output stage amplifiers is coupled in series to a respective driver stage amplifier among the plurality of driver stage amplifiers;
each of the plurality of driver stage amplifiers is coupled to the second amplifier input and configured to amplify the RF signal based on the second input voltage received at the second amplifier input; and
each of the plurality of output stage amplifiers is coupled to the first amplifier input and configured to:
receive the RF signal from the respective driver stage amplifier among the plurality of driver stage amplifiers; and
amplify the RF signal based on the first input voltage received at the first amplifier input.
7. The ET circuit of claim 1 wherein the control circuitry is further configured to couple the selected tracker circuit to the second amplifier input to provide the selected modulated voltage to the second amplifier input as the determined voltage.
8. The ET circuit of claim 7 wherein the selected tracker circuit is further configured to generate the selected modulated voltage as an ET modulated voltage.
9. The ET circuit of claim 7 wherein the control circuitry is further configured to couple the selected tracker circuit to the first amplifier input and the second amplifier input in response to the RF signal being modulated at a modulation bandwidth less than or equal to 100 MHz.
10. The ET circuit of claim 1 wherein the control circuitry is further configured to couple a second selected tracker circuit different from the selected tracker circuit among the first tracker circuit and the second tracker circuit to the second amplifier input to provide a second selected modulated voltage different from the selected modulated voltage among the first modulated voltage and the second modulated voltage to the second amplifier input as the determined voltage.
11. The ET circuit of claim 10 wherein:
the selected tracker circuit is further configured to generate the selected modulated voltage as an ET modulated voltage; and
the second selected tracker circuit is further configured to generate the second selected modulated voltage as an average power tracking (APT) modulated voltage.
12. The ET circuit of claim 1 further comprising a second amplifier array, the second amplifier array comprising:
a driver stage input configured to receive a driver stage voltage;
an output stage input configured to receive an output stage voltage; and
a plurality of second amplifier circuits each coupled to the driver stage input and the output stage input, the plurality of second amplifier circuits configured to amplify a second RF signal based on the driver stage voltage and the output stage voltage.
13. The ET circuit of claim 12 wherein the plurality of second amplifier circuits comprises a plurality of second driver stage amplifiers and a plurality of second output stage amplifiers, respectively, wherein:
each of the plurality of second output stage amplifiers is coupled in series to a respective second driver stage amplifier among the plurality of second driver stage amplifiers;
each of the plurality of second driver stage amplifiers is coupled to the driver stage input and configured to amplify the second RF signal based on the driver stage voltage received at the driver stage input; and
each of the plurality of second output stage amplifiers is coupled to the output stage input and configured to:
receive the second RF signal from the respective second driver stage amplifier among the plurality of second driver stage amplifiers; and
amplify the second RF signal based on the output stage voltage received at the output stage input.
14. The ET circuit of claim 12 wherein the control circuitry is further configured to:
couple the selected tracker circuit to the first amplifier input of the amplifier array to provide the selected modulated voltage to the amplifier array as the first input voltage; and
couple a second selected tracker circuit different from the selected tracker circuit among the first tracker circuit and the second tracker circuit to the driver stage input of the second amplifier array to provide a second selected modulated voltage different from the selected modulated voltage among the first modulated voltage and the second modulated voltage to the second amplifier array as the driver stage voltage.
15. The ET circuit of claim 14 wherein the control circuitry is further configured to:
couple the selected tracker circuit to the second amplifier input to provide the selected modulated voltage to the amplifier array as the second input voltage; and
couple the second selected tracker circuit to the output stage input to provide the second selected modulated voltage to the second amplifier array as the output stage voltage.
16. The ET circuit of claim 15 wherein the selected tracker circuit and the second selected tracker circuit are further configured to generate the selected modulated voltage and the second selected modulated voltage, respectively, as an ET modulated voltage.
17. The ET circuit of claim 15 wherein the control circuitry is further configured to couple the selected tracker circuit and the second selected tracker circuit to the amplifier array and the second amplifier array, respectively, in response to the RF signal and the second RF signal being modulated at a modulation bandwidth less than or equal to 100 MHz.
18. The ET circuit of claim 14 wherein the control circuitry is further configured to:
provide a constant voltage to the second amplifier input of the amplifier array as the second input voltage; and
provide the constant voltage to the output stage input of the second amplifier array as the output stage voltage.
19. The ET circuit of claim 18 wherein the control circuitry is further configured to provide the constant voltage to the second amplifier input and the driver stage input in response to the RF signal being modulated at a modulation bandwidth greater than 100 MHz.
20. The ET circuit of claim 18 further comprising low dropout regulator (LDO) circuitry configured to generate the constant voltage.