Biasing scheme for power amplifiers
A front-end module comprises a low-dropout (LDO) voltage regulator, a reference current generator, a power amplifier, and a voltage reference configured to provide a reference voltage to the LDO voltage regulator and the reference current generator. The LDO voltage regulator, reference current generator, power amplifier, and voltage reference are integrated on a first semiconductor die.
1. A front-end module comprising:
a low-dropout (LDO) voltage regulator;
a reference current generator directly connected to the LDO voltage regulator;
a power amplifier directly connected to the reference current generator;
a mode detector directly connected to the LDO voltage regulator, reference current generator, and power amplifier, the mode detector configured to generate a power-down signal to power down the LDO voltage regulator; and
a voltage reference directly connected to the LDO voltage regulator, the reference current generator, the power amplifier, and the mode detector, the voltage reference configured to provide a reference voltage to the LDO voltage regulator and the reference current generator;
the LDO voltage regulator, reference current generator, power amplifier, and voltage reference being integrated on a first semiconductor die.
2. The front-end module of claim 1 wherein the voltage reference is a bandgap voltage reference.
3. The front-end module of claim 1 wherein the power amplifier is a Silicon-On-Insulator (SOI) complementary metal-oxide-semiconductor (CMOS) power amplifier.
4. The front-end module of claim 1 wherein the power amplifier comprises three or more field-effect transistors and wherein the power amplifier is configured to generate three or more different bias voltages.
5. The front-end module of claim 1 wherein the power amplifier includes an n-channel metal-oxide field-effect transistor (NMOSFET).
6. The front-end module of claim 1 wherein the LDO voltage regulator is configured to be turned off in sleep mode.
7. The front-end module of claim 1 wherein the mode detector is a direct current (DC) mode detector operating at less than 50 nA.
8. The front-end module of claim 1 wherein the mode detector is configured to be maintained in an always-alive state.
9. The front-end module of claim 1 wherein the power amplifier is configured to operate at a first level during transmit modes and operate at a second level during non-transmit modes.
10. The front-end module of claim 1 further comprising a logic level slicer directly connected to the LDO voltage regulator, the reference current generator, the mode detector, and the voltage reference and configured to convert multiple logic levels to a single logic level.
11. The front-end module of claim 10 further comprising a logic decoder directly connected to an output of the logic level slicer and an output of the LDO voltage regulator.
12. The front-end module of claim 11 further comprising a level shifter directly connected to an output of the logic decoder.
13. A semiconductor die comprising:
a substrate;
a low-dropout (LDO) voltage regulator;
a reference current generator directly connected to the LDO voltage regulator;
a power amplifier directly connected to the reference current generator; and
a voltage reference directly connected to the LDO voltage regulator, the reference current generator, and the power amplifier, the voltage reference configured to provide a reference voltage to the LDO voltage regulator and the reference current generator.
14. The semiconductor die of claim 13 wherein the voltage reference is a bandgap voltage reference.
15. The semiconductor die of claim 13 wherein the power amplifier is a Silicon-On-Insulator (SOI) complementary metal-oxide-semiconductor (CMOS) power amplifier.
16. The semiconductor die of claim 13 wherein the LDO voltage regulator is configured to be turned off in sleep mode.
17. The semiconductor die of claim 13 further comprising a mode detector configured to generate a power-down signal to power down the LDO voltage regulator.
18. The semiconductor die of claim 17 wherein the mode detector is configured to be maintained in an always-alive state.
19. The semiconductor die of claim 13 wherein the reference current generator comprises a junction temperature sensor configured to detect a junction temperature value of the power amplifier and convert the junction temperature value to an output voltage value, an n-bit analog-to-digital converter configured to convert the output voltage value into digital bits, and a current source configured to generate discrete reference current levels for specific junction temperature regions based on the digital bits.
20. The semiconductor die of claim 13 wherein the power amplifier is configured to operate at a first level during transmit modes and operate at a second level during non-transmit modes.