Multi-level envelope tracking systems with separate DC and AC paths
地域：
CA
CA Irvine
摘要
Multi-level envelope tracking systems with separate DC and AC paths are provided. In certain embodiments, an envelope tracking system for generating a power amplifier supply voltage for a power amplifier is provided. The envelope tracking system includes a multi-level supply (MLS) DC-to-DC converter that outputs multiple regulated voltages, an MLS modulator that controls selection of the regulated voltages over time based on an envelope signal corresponding to an envelope of a radio frequency (RF) signal amplified by the power amplifier, an AC path filter coupled between an output of the MLS modulator and the power amplifier supply voltage, and a DC path filter coupled between a DC voltage and the power amplifier supply voltage.
說明書
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This application is a continuation of U.S. application Ser. No. 16/948,542, filed Sep. 23, 2020, and titled “MULTI-LEVEL ENVELOPE TRACKING SYSTEMS WITH SEPARATE DC AND AC PATHS,” which claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Patent Application No. 62/907,120, filed Sep. 27, 2019 and titled “MULTI-LEVEL ENVELOPE TRACKING SYSTEMS WITH SEPARATE DC AND AC PATHS,” which is herein incorporated by reference in its entirety.
Embodiments of the invention relate to electronic systems, and in particular, to power amplifiers for radio frequency (RF) electronics.
Power amplifiers are used in RF communication systems to amplify RF signals for transmission via antennas. It is 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, customer-premises equipment (CPE), laptops, and wearable electronics. For example, in wireless 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 410 MHz to about 7.125 GHz for fifth generation (5G) communications in frequency range 1 (FR1).
權(quán)利要求
What is claimed is:1. A mobile device comprising:a transceiver configured to generate a radio frequency signal for transmission; a front end circuit including a power amplifier configured to amplify the radio frequency signal and to receive power from a power amplifier supply voltage; and a power management circuit including an envelope tracker that includes a DC-to-DC converter configured to output a plurality of regulated voltages, a modulator including a modulator output and a plurality of switches each coupled between the modulator output and a corresponding one of the plurality of regulated voltages, a modulator control circuit configured to control activation of the plurality of switches based on an envelope of the radio frequency signal, a first filter coupled between the modulator output and the power amplifier supply voltage, and a second filter coupled between a DC voltage and the power amplifier supply voltage. 2. The mobile device of claim 1 wherein the DC-to-DC converter is further configured to generate the DC voltage. 3. The mobile device of claim 1 further comprising a battery that provides a battery voltage, the DC-to-DC converter configured to generate the plurality of regulated voltages and the DC voltage based on providing DC-to-DC conversion of the battery voltage. 4. The mobile device of claim 1 wherein the first filter includes at least one series inductor and at least one shunt capacitor. 5. The mobile device of claim 1 wherein the envelope tracker further includes a controllable delay circuit configured to control a relative delay between an AC path through the first filter and a DC path through the second filter. 6. The mobile device of claim 5 wherein the controllable delay circuit includes a plurality of controllable delay buffers each configured to control a delay of a respective one of plurality of regulated voltages. 7. The mobile device of claim 1 wherein each of the plurality of regulated voltages has a different voltage level. 8. An envelope tracking system comprising:a power amplifier configured to amplify a radio frequency signal and to receive power from a power amplifier supply voltage; and an envelope tracker including a DC-to-DC converter configured to output a plurality of regulated voltages, a modulator including a modulator output and a plurality of switches each coupled between the modulator output and a corresponding one of the plurality of regulated voltages, a modulator control circuit configured to control activation of the plurality of switches based on an envelope of the radio frequency signal, a first filter coupled between the modulator output and the power amplifier supply voltage, and a second filter coupled between a DC voltage and the power amplifier supply voltage. 9. The envelope tracking system of claim 8 wherein the DC-to-DC converter is further configured to generate the DC voltage. 10. The envelope tracking system of claim 8 wherein each of the plurality of regulated voltages has a different voltage level. 11. The envelope tracking system of claim 8 wherein the first filter includes at least one series inductor and at least one shunt capacitor. 12. The envelope tracking system of claim 11 wherein the first filter further includes a DC blocking capacitor in series between the modulator output and the power amplifier supply voltage. 13. The envelope tracking system of claim 8 wherein the second filter includes at least one series inductor and at least one shunt capacitor. 14. The envelope tracking system of claim 8 wherein the envelope tracker further includes a controllable delay circuit configured to control a relative delay between an AC path through the first filter and a DC path through the second filter. 15. The envelope tracking system of claim 14 wherein the controllable delay circuit includes a plurality of controllable delay buffers each configured to control a delay of a respective one of the plurality of regulated voltages. 16. The envelope tracking system of claim 8 wherein a DC path through the second filter carries at least seventy five percent of the energy provided from the envelope tracker to the power amplifier. 17. A method of envelope tracking, the method comprising:amplifying a radio frequency signal using a power amplifier that is powered by a power amplifier supply voltage from an envelope tracker; generating a plurality of regulated voltages using a DC-to-DC converter of the envelope tracker; controlling activation of a plurality of switches of a modulator of the envelope tracker based on an envelope of the radio frequency signal, the plurality of switches each coupled between a modulator output and a corresponding one of the plurality of regulated voltages; controlling the power amplifier supply voltage using a first filter that is between the modulator output and the power amplifier supply voltage; and controlling the power amplifier supply voltage using a second filter that is between a DC voltage and the power amplifier supply voltage. 18. The method of claim 17 further comprising generating the DC voltage using the DC-to-DC converter. 19. The method of claim 17 further comprising providing DC blocking using a series DC blocking capacitor of the first filter. 20. The method of claim 17 further comprising controlling a relative delay between an AC path through the first filter and a DC path through the second filter using a controllable delay circuit.
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