Power amplification system with adjustable common base bias
Power amplification system with adjustable common base bias. A power amplification system can include a first transistor having a base coupled to a radio-frequency input. The power amplification can further include a second transistor having an emitter coupled to a collector of the first transistor and having a collector coupled to a radio-frequency output. The power amplification system can include a biasing component configured to apply a fixed biasing signal to the base of the first transistor and to apply an adjustable biasing signal to the base of the second transistor.
1. A power amplification system comprising:
a first transistor having a base coupled to a radio-frequency input;
a second transistor having an emitter coupled to a collector of the first transistor and having a collector coupled to a radio-frequency output; and
a biasing component configured to apply a fixed biasing signal to the base of the first transistor and to apply an adjustable biasing signal to the base of the second transistor, the biasing component including a digital circuit that stores a table of biasing voltage values, each biasing voltage value in respective association with at least one of a plurality of temperature values and a plurality of power conditions.
2. The power amplification system of claim 1 wherein the biasing component is configured to apply the adjustable biasing signal based on a temperature of the power amplification system.
3. The power amplification system of claim 2 wherein the biasing component is configured to apply a higher adjustable biasing signal in response to a lower temperature and a lower adjustable biasing signal in response to a higher temperature.
4. The power amplification system of claim 2 further comprising a temperature sensor.
5. The power amplification system of claim 2 wherein the biasing component is configured to receive a temperature signal indicative of the temperature.
6. The power amplification system of claim 1 wherein the biasing component is configured to apply the adjustable biasing signal based on a power condition of the power amplification system.
7. The power amplification system of claim 6 wherein the biasing component is configured to apply a higher adjustable biasing signal in response to a higher output power and a lower adjustable biasing signal in response to a lower output power.
8. The power amplification system of claim 6 further comprising a power sensor.
9. The power amplification system of claim 8 wherein the power sensor is coupled to a supply voltage.
10. The power amplification system of claim 9 wherein the collector of the second transistor is coupled to the supply voltage via an inductor.
11. The power amplification system of claim 8 wherein the biasing component is coupled to the base of the second transistor.
12. The power amplification system of claim 8 wherein the biasing component receives a power signal indicative of the power condition.
13. The system of claim 1 wherein the biasing component is configured to apply the adjustable biasing signal based on a modulation standard of the radio-frequency input.
14. The system of claim 1 wherein the adjustable biasing signal is an adjustable biasing voltage.
15. The system of claim 1 wherein the biasing component includes an analog circuit that provides the adjustable biasing signal.
16. The system of claim 1 wherein the biasing component includes a third transistor having a collector coupled to a battery voltage, an emitter coupled to the base of the second transistor, and a base coupled to a buffer amplifier.
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 first transistor having a base coupled to a radio-frequency input, a second transistor having an emitter coupled to a collector of the first transistor and having a collector coupled to a radio-frequency output, and a biasing component configured to apply a fixed biasing signal to the base of the first transistor and to apply an adjustable biasing signal to the base of the second transistor, the biasing component including a digital circuit that stores a table of biasing voltage values, each biasing voltage value in respective association with at least one of a plurality of temperature values and a plurality of power conditions.
18. The RF module of claim 17 wherein the RF module is a front-end module (FEM).
19. A wireless device comprising:
a transceiver configured to generate a radio-frequency signal;
a front-end module (FEM) in communication with the transceiver, the FEM including a packaging substrate configured to receive a plurality of components, the FEM further including a power amplification system implemented on the packaging substrate, the power amplification system including a first transistor having a base coupled to a radio-frequency input to receive the radio-frequency signal, a second transistor having an emitter coupled to a collector of the first transistor and having a collector coupled to a radio-frequency output, and a biasing component configured to apply a fixed biasing signal to the base of the first transistor and to apply an adjustable biasing signal to the base of the second transistor, the biasing component including a digital circuit that stores a table of biasing voltage values, each biasing voltage value in respective association with at least one of a plurality of temperature values and a plurality of power conditions, and
an antenna in communication with the FEM, the antenna configured to transmit an amplified version of the radio-frequency signal received from the radio-frequency output.
20. The wireless device of claim 19 wherein the RF module is a front-end module (FEM).