Enhanced amplifier efficiency through cascode current steering
According to some implementations, a power amplifier (PA) includes a common emitter configured to receive a radio-frequency (RF) signal. The PA also includes a carrier amplifier coupled to the common emitter to form a carrier cascode configuration, a collector of the carrier amplifier provided with a first supply voltage. The PA further includes a peaking amplifier coupled to the common emitter to form a peaking cascode configuration, a collector of the peaking amplifier provided with a second supply voltage greater than the first supply voltage.
1. A power amplifier (PA) comprising:
a common emitter configured to receive a radio-frequency (RF) signal;
a carrier amplifier coupled to the common emitter to form a carrier cascode configuration, a collector of the carrier amplifier provided with a first supply voltage; and
a peaking amplifier coupled to the common emitter to form a peaking cascode configuration, a collector of the peaking amplifier provided with a second supply voltage greater than the first supply voltage, substantially all of a collector current of the power amplifier obtained from either the first supply voltage or the second supply voltage based on a selected value of an output power of the power amplifier.
2. The power amplifier of claim 1 wherein each of the carrier and peaking amplifiers is provided with a bias voltage to allow the respective amplifier to be turned on and off.
3. The power amplifier of claim 2 wherein the carrier amplifier is turned on by having its bias voltage set to a high level and the peaking amplifier is turned off by having its bias voltage set to a ground level, when the output power (Pout) of the power amplifier is less than the selected value.
4. The power amplifier of claim 3 wherein substantially all of the collector current of the power amplifier is obtained from the first supply voltage to yield a maximum or increased efficiency at the output power.
5. The power amplifier of claim 3 wherein the carrier amplifier is turned off by having its bias voltage set to the ground level and the peaking amplifier is turned on by having its bias voltage set to the high level, when Pout is greater than the selected value.
6. The power amplifier of claim 5 wherein substantially all of the collector current of the power amplifier is obtained from the second supply voltage to yield an increase in maximum output power.
7. The power amplifier of claim 5 wherein the selected value is saturation power level (Psat) minus 3 dB.
8. The power amplifier of claim 2 wherein the carrier cascode configuration and the peaking cascode configuration substantially preserve a gain of the power amplifier in either configuration.
9. The power amplifier of claim 2 wherein the power amplifier has minimized or reduced discontinuity in an amplitude-to-amplitude (AM-AM) response during a transition between the first and second supply voltages.
10. A radio-frequency (RF) module comprising:
a packaging substrate configured to receive a plurality of components; and
a power amplifier (PA) implemented on the packaging substrate, the power amplifier including a common emitter configured to receive a radio-frequency signal, the power amplifier further including a carrier amplifier coupled to the common emitter to form a carrier cascode configuration, a collector of the carrier amplifier provided with a first supply voltage, the power amplifier further including a peaking amplifier coupled to the common emitter to form a peaking cascode configuration, a collector of the peaking amplifier provided with a second supply voltage greater than the first supply voltage, substantially all of a collector current of the power amplifier obtained from either the first supply voltage or the second supply voltage based on a selected value of an output power of the power amplifier.
11. The radio-frequency module of claim 10 wherein the radio-frequency module is a front-end module (FEM).
12. The radio-frequency module of claim 10 wherein each of the carrier and peaking amplifiers is provided with a bias voltage to allow the respective amplifier to be turned on and off.
13. The radio-frequency module of claim 12 wherein the carrier amplifier is turned on by having its bias voltage set to a high level and the peaking amplifier is turned off by having its bias voltage set to a ground level, when the output power (Pout) of the power amplifier is less than the selected value.
14. The radio-frequency module of claim 13 wherein substantially all of the collector current of the power amplifier is obtained from the first supply voltage to yield a maximum or increased efficiency at the output power.
15. The radio-frequency module of claim 13 wherein the carrier amplifier is turned off by having its bias voltage set to the ground level and the peaking amplifier is turned on by having its bias voltage set to the high level, when Pout is greater than the selected value.
16. The radio-frequency module of claim 15 wherein substantially all of the collector current of the power amplifier is obtained from the second supply voltage to yield an increase in maximum output power.
17. The radio-frequency module of claim 12 wherein the carrier cascode configuration and the peaking cascode configuration substantially preserve a gain of the power amplifier in either configuration.
18. A radio-frequency (RF) device comprising:
a transceiver configured to generate a radio-frequency signal;
a front-end module (FEM) in communication with the transceiver, the front-end module including a packaging substrate configured to receive a plurality of components, the front-end module further including a power amplifier (PA) implemented on the packaging substrate, the power amplifier including a common emitter configured to receive an radio-frequency signal, the power amplifier further including a carrier amplifier coupled to the common emitter to form a carrier cascode configuration, a collector of the carrier amplifier provided with a first supply voltage, the power amplifier further including a peaking amplifier coupled to the common emitter to form a peaking cascode configuration, a collector of the peaking amplifier provided with a second supply voltage greater than the first supply voltage, substantially all of a collector current of the power amplifier obtained from either the first supply voltage or the second supply voltage based on a selected value of an output power of the power amplifier; and
an antenna in communication with the front-end module, the antenna configured to transmit an amplified radio-frequency signal.
19. The radio-frequency device of claim 18 wherein the radio-frequency device includes a wireless device.
20. The radio-frequency device of claim 19 wherein the wireless device includes at least one of a base station, a repeater, a cellular phone, a smartphone, a computer, a laptop, a tablet computer, and a peripheral device.