Power amplification system with shared common base biasing

1. A power amplification system comprising:

a plurality of cascode amplifier sections, each one of the plurality of cascode amplifier sections including a first transistor and a second transistor;

a plurality of common emitter biasing components, each one of the plurality of common emitter biasing components coupled to a base of the first transistor of a respective one of the plurality of cascode amplifier sections and controllable to bias the first transistor of the respective one of the plurality of cascode amplifier sections;

a common base biasing component coupled to a base of the second transistor of each of the plurality of cascode amplifier sections and controllable to bias the second transistor of each of the plurality of cascode amplifier sections; and

a controller configured to control the plurality of common emitter biasing components based on a band select signal.

2. The power amplification system of claim 1 wherein the controller is configured to, based on the band select signal, enable one or more of the plurality of common emitter biasing components to provide a respective first biasing signal to the base of the first transistor of a respective one or more of the plurality of cascode amplifier sections.

3. The power amplification system of claim 2 wherein the controller is configured to, irrespective of the band select signal, enable the common base biasing component to provide a second biasing signal to the bases of the second transistors of each of the plurality of cascode amplifier sections.

4. The power amplification system of claim 3 wherein the first biasing signals are based on a target output power.

5. The power amplification system of claim 3 wherein the second biasing signal is based on a target output power.

6. The power amplification system of claim 3 , wherein the second biasing signal is derived from a current source coupled to the common base biasing component and powered by voltage from a battery.

7. The power amplification system of claim 3 wherein the first biasing signals are derived from respective current sources coupled to the one or more of the plurality of common emitter biasing components and powered by voltage from a battery.

8. The power amplification system of claim 1 further comprising a plurality of RC decoupling components, each of the RC decoupling components including a resistor coupled between the common base biasing component and the base of the second transistor of a respective one of the plurality of cascode amplifier sections and further including a capacitor coupled between the base of the second transistor of the respective one of the plurality of cascode amplifier sections and a ground voltage.

9. The power amplification system of claim 1 wherein a collector of the second transistor of each of the plurality of second transistors is coupled to a supply voltage via a respective inductor.

10. The power amplification system of claim 1 wherein a collector of the second transistor of each of the plurality of second transistors is coupled to an antenna switch component via a respective output matching and filtering component.

11. The power amplification system of claim 10 wherein each of the plurality of output matching and filtering components correspond to a respective one of a plurality of frequency bands.

12. The power amplification system of claim 10 wherein each of the plurality of matching and filtering components is configured to filter an output RF signal with a filter centered at a respective one of a plurality of frequency bands.

13. The power amplification system of claim 10 wherein the antenna switch component is configured to output the signal received at a selected one of the plurality of output matching and filtering components.

14. The power amplification system of claim 10 wherein the antenna switch component is configured to combine and output the signals received at a plurality of the plurality of output matching and filtering components.

15. The power amplification system of claim 1 further comprising a plurality of input matching components coupled to the base of the first transistor of a respective one of the plurality of cascode amplifier sections and configured to match an input RF signal at a respective one of a plurality of frequency bands.

16. The power amplification system of claim 15 further comprising a plurality of RC decoupling components, each one of the RC decoupling components including a resistor coupled between a respective common emitter biasing component and the base of the first transistor of a respective one of the plurality of cascode amplifier sections and further including a capacitor coupled between the base of the second transistor of the respective one of the plurality of cascode amplifier sections and a respective one of the plurality of input matching components.

17. A radio-frequency (RF) module comprising:

a packaging substrate configured to receive a plurality of components; and

a power amplification system implemented on the packaging substrate, the power amplification system including a plurality of cascode amplifier sections, each one of the plurality of cascode amplifier sections including a first transistor and a second transistor, a plurality of common emitter biasing components, each one of the plurality of common emitter biasing components coupled to a base of the first transistor of a respective one of the plurality of cascode amplifier sections and controllable to bias the first transistor of the respective one of the plurality of cascode amplifier sections, a common base biasing component coupled to a base of the second transistor of each of the plurality of cascode amplifier sections and controllable to bias the second transistor of each of the plurality of cascode amplifier sections, and a controller configured to control the plurality of common emitter biasing components based on a band select signal.

18. The radio-frequency module of claim 17 wherein the radio-frequency module is a front-end module (FEM).

19. A wireless device comprising:

a transceiver configured to generate a radio-frequency (RF) 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 amplification system implemented on the packaging substrate, the power amplification system including a plurality of cascode amplifier sections, each one of the plurality of cascode amplifier sections including a first transistor and a second transistor, a plurality of common emitter biasing components, each one of the plurality of common emitter biasing components coupled to a base of the first transistor of a respective one of the plurality of cascode amplifier sections and controllable to bias the first transistor of the respective one of the plurality of cascode amplifier sections, a common base biasing component coupled to a base of the second transistor of each of the plurality of cascode amplifier sections and controllable to bias the second transistor of each of the plurality of cascode amplifier sections, and a controller configured to control the plurality of common emitter biasing components based on a band select signal; and

an antenna in communication with the front-end module, the antenna configured to transmit an amplified version of the RF signal.

20. The wireless device of claim 19 wherein the controller is configured to, based on the band select signal, enable one or more of the plurality of common emitter biasing components to provide a respective first biasing signal to the base of the first transistor of a respective one or more of the plurality of cascode amplifier sections.