BACKGROUND

Field

Embodiments of the invention relate to electronic systems, and in particular, to power amplifiers for radio frequency (RF) electronics.

Description of the Related Technology

Power amplifiers are used in RF communication systems to amplify RF signals for transmission via antennas. It can be important to manage the power of RF signal transmissions to prolong battery life and/or provide a suitable transmit power level.

Examples of RF communication systems with one or more power amplifiers include, but are not limited to, mobile phones, tablets, base stations, network access points, laptops, and wearable electronics. For example, in mobile devices that communicate using a cellular standard, a wireless local area network (WLAN) standard, and/or any other suitable communication standard, a power amplifier can be used for RF signal amplification. An RF signal can have a frequency in the range of about 30 kHz to 300 GHz, such as in the range of about 450 MHz to about 6 GHz for certain communications standards.

SUMMARY

In certain embodiments, the present disclosure relates to a power amplifier system. The power amplifier system includes a power amplification stage configured to amplify a radio frequency signal, at least one output envelope detector configured to generate one or more detection signals indicating an output signal envelope of the power amplification stage, a feedback circuit configured to provide positive envelope feedback to a bias of the power amplification stage based on the one or more detection signals, and a supply modulator configured to control a voltage level of a supply voltage of the power amplification stage based on the one or more detection signals such that the supply voltage is modulated with the output signal envelope through positive envelope feedback.

In various embodiments, the at least one output envelope detector includes a current mode detector electrically coupled to an output of the power amplification stage.

In several embodiments, the feedback circuit includes a wideband voltage shifter. In accordance with a number of embodiments, the wideband voltage shifter includes a first resistor including a first end configured to receive a first detection signal of the one or more detection signals and a second end configured to generate a positive envelope feedback signal operable to control the bias of the power amplification stage. According to various embodiments, the wideband voltage shifter further includes a voltage source and a second resistor electrically connected between the second end of the first resistor and the voltage source, the first resistor and the second resistor configured to operate as a voltage divider. In accordance with several embodiments, the voltage source is operable to control a quiescent bias voltage of the power amplification stage.

In some embodiments, the power amplification stage includes a field-effect transistor configured to amplify the radio frequency signal, the feedback circuit configured to provide positive envelope feedback to a gate of the field-effect transistor based on the one or more detection signals. In accordance with a number of embodiments, the feedback circuit includes an output configured to generate a positive envelope feedback signal based on the detection signal, the power amplifier system further including a bias choke inductor electrically connected between the output of the feedback circuit and the gate of the field-effect transistor. According to several embodiments, the supply modulator includes an output configured to generate the supply voltage, the power amplification stage further including a supply choke inductor electrically connected between the output of the supply modulator and a drain of the field-effect transistor.

In several embodiments, the power amplification stage includes a bipolar transistor configured to amplify the radio frequency signal, the feedback circuit configured to provide positive envelope feedback to a base of the bipolar transistor based on the detection signal. According to some embodiments, the feedback circuit includes an output configured to generate a positive envelope feedback signal based on the detection signal, the power amplifier system further including a bias choke inductor electrically connected between the output of the feedback circuit and the base of the bipolar transistor. In accordance with a number of embodiments, the supply modulator includes an output configured to generate the supply voltage, the power amplification stage further including a supply choke inductor electrically connected between the output of the supply modulator and a collector of the bipolar transistor.

In some embodiments, the power amplification stage is an output stage, the power amplifier system further including an input stage configured to provide the radio frequency signal to the output stage. According to several embodiments, the power amplifier system further including an input stage envelope detector configured to generate a input stage detection signal indicating an output signal envelope of the input stage, an input stage feedback circuit configured to provide positive envelope feedback to a bias of the input stage based on the input stage detection signal, and an input stage supply modulator configured to control a voltage level of an input stage supply voltage of the input stage based on the detection signal through positive envelope feedback.

In various embodiments, the supply modulator is further configured to receive a conditioning signal, and to control the supply voltage based on the conditioning signal. According to a number of embodiments, the conditioning signal provides a coarse adjustment to the supply voltage and the one or more detection signals provides a fine adjustment to the supply voltage. In accordance with several embodiments, the supply modulator includes a DC-to-DC converter configured to receive a battery voltage and to output the supply voltage, the DC-to-DC converter controlled based on the conditioning signal and the one or more detection signals. According to some embodiments, the conditioning signal is generated by an input envelope detector. In accordance with a number of embodiments, the condition signal is generated by an inter-stage envelope detector. According to several embodiments, the conditioning signal is generated by a baseband processor.

In certain embodiments, the present disclosure relates to a packaged module including a package substrate, a first die attached to the package substrate, and a second die attached to the package substrate. The first die includes a power amplification stage configured to amplify a radio frequency signal, at least one output envelope detector configured to generate one or more detection signals indicating an output signal envelope of the power amplification stage, and a feedback circuit configured to provide positive envelope feedback to a bias of the power amplification stage based on the one or more detection signals. The second die includes a supply modulator configured to control a voltage level of a supply voltage of the power amplification stage based on the one or more detection signals such that the supply voltage is modulated with the output signal envelope through positive envelope feedback.

In some embodiments, the at least one output envelope detector includes a current mode detector electrically coupled to an output of the power amplification stage.

In several embodiments, the feedback circuit includes a wideband voltage shifter. According to a number of embodiments, the wideband voltage shifter includes a first resistor including a first end configured to receive a first detection signal of the one or more detection signals and a second end configured to generate a positive envelope feedback signal operable to control the bias of the power amplification stage. In accordance with various embodiments, the wideband voltage shifter further includes a voltage source and a second resistor electrically connected between the second end of the first resistor and the voltage source, the first resistor and the second resistor configured to operate as a voltage divider. According to some embodiments, the voltage source is operable to control a quiescent bias voltage of the power amplification stage.

In various embodiments, the power amplification stage includes a field-effect transistor configured to amplify the radio frequency signal, the feedback circuit configured to provide positive envelope feedback to a gate of the field-effect transistor based on the one or more detection signals. In accordance with a number of embodiments, the feedback circuit includes an output configured to generate a positive envelope feedback signal based on the detection signal, the power amplifier system further including a bias choke inductor attached to the package substrate and electrically connected between the output of the feedback circuit and the gate of the field-effect transistor. According to several embodiments, the supply modulator includes an output configured to generate the supply voltage, the power amplification stage further including a supply choke inductor attached to the package substrate and electrically connected between the output of the supply modulator and a drain of the field-effect transistor.

In several embodiments, the power amplification stage includes a bipolar transistor configured to amplify the radio frequency signal, the feedback circuit configured to provide positive envelope feedback to a base of the bipolar transistor based on the detection signal. According to some embodiments, the feedback circuit includes an output configured to generate a positive envelope feedback signal based on the detection signal, the power amplifier system further including a bias choke inductor attached to the package substrate and electrically connected between the output of the feedback circuit and the base of the bipolar transistor. In accordance with a number of embodiments, the supply modulator includes an output configured to generate the supply voltage, the power amplification stage further including a supply choke inductor attached to the package substrate and electrically connected between the output of the supply modulator and a collector of the bipolar transistor.

In various embodiments, the power amplification stage is an output stage, the first die further including an input stage configured to provide the radio frequency signal to the output stage. According to several embodiments, the first die further including an input stage envelope detector configured to generate a input stage detection signal indicating an output signal envelope of the input stage, and an input stage feedback circuit configured to provide positive envelope feedback to a bias of the input stage based on the input stage detection signal. In accordance with a number of embodiments, the second die further includes an input stage supply modulator configured to control a voltage level of an input stage supply voltage of the input stage based on the detection signal through positive envelope feedback.

In some embodiments, the supply modulator is further configured to receive a conditioning signal, and to control the supply voltage based on the conditioning signal. According to various embodiments, the conditioning signal provides a coarse adjustment to the supply voltage and the one or more detection signals provides a fine adjustment to the supply voltage. In accordance with several embodiments, the supply modulator includes a DC-to-DC converter configured to receive a battery voltage and to output the supply voltage, the DC-to-DC converter controlled based on the conditioning signal and the one or more detection signals. According to some embodiments, the conditioning signal is generated by an input envelope detector. In accordance with a number of embodiments, the condition signal is generated by an inter-stage envelope detector. According to several embodiments, the conditioning signal is generated by a baseband processor.

In certain embodiments, the present disclosure relates to a method of amplification in a power amplifier system. The method includes amplifying a radio frequency signal using a power amplification stage, generating one or more detection signals indicating an output signal envelope of the power amplification stage using at least one output envelope detector, providing positive envelope feedback to a bias of the power amplification stage based on the one or more detection signals using a feedback circuit, and controlling a voltage level of a supply voltage of the power amplification stage based on the one or more detection signals using a supply modulator so as to modulate the supply voltage with the output signal envelope through positive envelope feedback.

In various embodiments, providing positive envelope feedback to the bias of the power amplification stage includes controlling a gate bias of a field effect transistor of the power amplification stage.

In a number of embodiments, providing positive envelope feedback to the bias of the power amplification stage includes controlling a base bias of a bipolar transistor of the power amplification stage.

In several embodiments, generating the one or more detection signals includes extracting the output signal envelope from an output of the power amplification stage using a current mode detector.

In some embodiments, controlling the voltage level of the supply voltage comprises providing a coarse adjustment to the voltage level based on a conditioning signal and providing a fine adjustment to the voltage level based on the one or more detection signals.

