Control of switcher regulated power amplifier modules
Various embodiments described herein relate to a power management block and an amplification block used in the transmitter of a communication subsystem. The power management block provides improved control for the gain control signal provided to a pre-amplifier and the supply voltage provided to a power amplifier which are both in the amplification block. The power expended by the power amplifier is optimized by employing a continuous control method in which one or more feedback loops are employed to take into account various characteristics of the transmitter components and control values.
1. A transmitter for a wireless communications device, wherein the transmitter comprises:
a power amplification block comprising:
a pre-amplifier configured to amplify a transmission signal to produce a pre-amplified transmission signal; and
a power amplifier coupled to the pre-amplifier and configured to amplify the pre-amplified transmission signal to produce an amplified transmission signal;
a detector coupled to the output of the pre-amplifier and configured to provide a detected pre-amp output signal; and
a power management block comprising:
a switching regulator control block configured to generate a switching supply control signal by applying a switching control transfer function to the detected pre-amp output signal; and
a switched mode power supply coupled to the switching regulator control block and configured to generate a supply voltage signal based on the switching supply control signal and provide the supply voltage signal to the power amplifier;
wherein the switching control transfer function is derived based on a characterization of the response of the detector, control curves of the switched mode power supply, and a response of the power amplifier to input drive.
2. The transmitter of claim 1 , wherein the switching regulator control block is further configured to also use a trim signal to generate the switching supply control signal, the trim signal being generated to compensate for tolerances of components used to build the transmitter.
3. The transmitter of claim 1 , wherein the switching regulator control block is configured to provide control values to the switched mode power supply to hold the power amplifier in a state of constant compression.
4. The transmitter of claim 1 , wherein the power management block further comprises a power limit control block configured to provide a gain control signal to the pre-amplifier to limit the transmission power of the power amplification block, wherein the power limit control block is coupled to the detector and generates the gain control signal based on the detected pre-amp output signal, a transmit power limit signal and a second gain control signal.
5. The transmitter of claim 1 , wherein the power management block further comprises a compensating control block configured to provide a gain correction signal based on the supply voltage signal, and wherein the gain correction signal is subtracted from an automatic gain control (AGC) signal to generate a gain control signal for the pre-amplifier.
6. A mobile communication device comprising:
a main processor configured to control the operation of the mobile communication device;
a communication subsystem connected to the main processor, the communication subsystem being configured to send and receive data, the communication subsystem comprising
a power amplification block comprising a pre-amplifier configured to amplify a transmission signal to produce a pre-amplified transmission signal; and a power amplifier coupled to the pre-amplifier and configured to amplify the pre-amplified transmission signal to produce an amplified transmission signal;
a detector coupled to the output of the pre-amplifier and configured to provide a detected pre-amp output signal; and
a power management block comprising a switching regulator control block configured to generate a switching supply control signal by applying a switching control transfer function to the detected pre-amp output signal; and
a switched mode power supply coupled to the switching regulator control block and configured to generate a supply voltage signal based on the switching supply control signal and provide the supply voltage signal to the power amplifier;
wherein the switching control transfer function is derived based on a characterization of the response of the detector, control curves of the switched mode power supply, and a response of the power amplifier to input drive.
7. The mobile communication device of claim 6 , wherein the switching regulator control block is further configured to use a trim signal to generate the switching supply control signal, the trim signal being generated to compensate for tolerances of components used to build the communication subsystem.
8. The mobile communication device of claim 6 , wherein the switching regulator control block is configured to provide control values to the switched mode power supply to hold the power amplifier in a state of constant compression.
9. The mobile communication device of claim 6 , wherein the power management block further comprises a power limit control block configured to provide a gain control signal to the pre-amplifier to limit the transmission power of the power amplification block, wherein the power limit control block is coupled to the detector and generates the gain control signal based on the detected pre-amp output signal, a transmit power limit signal and a second gain control signal.
10. The mobile communication device of claim 6 , wherein the power management block further comprises a compensating control block configured to provide a gain correction signal based on the supply voltage signal, and wherein the gain correction signal is subtracted from an automatic gain control (AGC) signal to generate a gain control signal for the pre-amplifier.
11. A method of providing a supply voltage signal to a power amplification block of a transmitter, the power amplification block comprising a pre-amplifier and a power amplifier, wherein the method comprises:
detecting the output of the pre-amplifier using a detector to provide a detected pre-amp output signal;
generating a switching supply control signal by applying a switching control transfer function to the detected pre-amp output signal; and
generating the supply voltage signal by providing the switching supply control signal to a switched mode power supply;
wherein the switching control transfer function is derived based on a characterization of the response of the detector, control curves of the switched mode power supply, and a response of the power amplifier to input drive.
12. The method of claim 11 , wherein the method further comprises using a trim signal to generate the switching supply control signal, the trim signal being generated to compensate for tolerances of components used to build the transmitter.
13. The method of claim 11 , wherein the method further comprises generating the switching supply control signal switching to provide the supply voltage signal to hold the power amplifier in a state of constant compression during use.
14. The method of claim 11 , wherein the method further comprises providing a gain control signal to the pre-amplifier to limit the transmission power of the power amplification block, wherein the gain control signal is generated based on the detected pre-amp output signal, a transmit power limit signal and a second gain control signal.
15. The method of claim 11 , wherein the method further comprises providing a gain correction signal based on the supply voltage signal, and subtracting the gain correction signal from an automatic gain control (AGC) signal to generate a gain control signal for the pre-amplifier.