Operating a power management circuit based on modulation bandwidth and power backoff

Abstract

Operating a power management circuit based on modulation bandwidth and power backoff is provided. The power management circuit includes a transceiver circuit, a power management integrated circuit (PMIC), and a power amplifier circuit that are configured to amplify a radio frequency (RF) signal for transmission in a wireless device. Herein, the power management circuit can be configured to operate under different operating conditions that are defined by modulation bandwidth of the RF signal and power backoff of the power amplifier circuit. The transceiver circuit is configured to adapt configurations and / or controls for the PMIC and / or the power amplifier circuit based on the different operating conditions. As a result, it is possible to improve power added efficiency (PAE), linearity, and / or noise tolerance in the power management circuit under the different operating conditions.

Description

OPERATING A POWER MANAGEMENT CIRCUIT BASED ON MODULATION BANDWIDTH AND POWER BACKOFFRelated Applications

[0001] This application claims the benefit of U.S. provisional patent application serial number 63 / 690,931 , filed on September 5, 2024, and U.S. provisional patent application serial number 63 / 720,832, filed on November 15, 2024, the disclosures of which are hereby incorporated herein by reference in their entireties.Field of the Disclosure

[0002] The present disclosure is related to operating a power management circuit in a wireless device based on modulation bandwidth and power backoff.Background

[0003] Mobile communication devices have become increasingly common in current society for providing wireless communication services. The prevalence of these mobile communication devices is driven in part by the many functions that are now enabled on such devices. Increased processing capabilities in such devices means that mobile communication devices have evolved from being pure communication tools into sophisticated mobile multimedia centers that enable enhanced user experiences.

[0004] The redefined user experience requires higher data rates offered by advanced wireless communication technologies such as fifth-generation new- radio (5G-NR). To achieve higher data rates, a mobile communication device is required to amplify a transmission signal to a desired power level to help overcome potential propagation losses and / or interferences. As such, the mobile communication device typically includes a transceiver circuit, a power amplifier circuit, and a power management circuit. Specifically, the transceiver circuit modulates the transmission signal to an intended transmission frequency, the power amplifier circuit amplifies the transmission signal to the desired power level, and the power management circuit supplies an envelope tracking (ET)voltage to the power amplifier circuit. Understandably, to achieve the best possible efficiency and performance, the power management circuit must adapt the ET voltage in accordance with a modulation bandwidth of the transmission signal.

[0005] Embodiments of the disclosure relate to operating a power management circuit based on modulation bandwidth and power backoff. The power management circuit includes a transceiver circuit, a power management integrated circuit (PMIC), and a power amplifier circuit that are configured to amplify a radio frequency (RF) signal for transmission in a wireless device. Herein, the power management circuit can be configured to operate under different operating conditions that are defined by modulation bandwidth of the RF signal and power backoff of the power amplifier circuit. The transceiver circuit is configured to adapt configurations and / or controls for the PMIC and / or the power amplifier circuit based on the different operating conditions. As a result, it is possible to improve power added efficiency (PAE), linearity, and / or noise tolerance in the power management circuit under the different operating conditions.

[0006] In one aspect, a power management circuit is provided. The power management circuit includes a PMIC. The PMIC is configured to generate a supply voltage based on a target voltage. The power management circuit also includes a power amplifier circuit. The power amplifier circuit includes a first power amplifier activated at all times and a second power amplifier activated conditionally to amplify an RF signal based on the supply voltage. The power amplifier circuit also includes an impedance modulation circuit. The impedance modulation circuit is coupled between a respective output of the first power amplifier and a respective output of the second power amplifier. The power management circuit also includes a transceiver circuit. The transceiver circuit is configured to determine that the power management circuit is configured to operate under one of a first operating condition, a second operating condition,and a third operating condition based on a modulation bandwidth of the RF signal and a predefined peak power backoff of the power amplifier circuit. The transceiver circuit is also configured to generate the target voltage based on a respective one of a first lookup table, a second lookup table, and a third lookup table under the determined one of the first operating condition, the second operating condition, and the third operating condition.

[0007] In another aspect, a method for operating a power management circuit based on modulation bandwidth and peak power backoff is provided. The method includes generating a supply voltage based on a target voltage. The method also includes activating a first power amplifier in a power amplifier circuit at all times and activating a second power amplifier in the power amplifier circuit conditionally to amplify an RF signal based on the supply voltage. The method also includes determining that the power management circuit is configured to operate under one of a first operating condition, a second operating condition, and a third operating condition based on a modulation bandwidth of the RF signal and a predefined power backoff of the power amplifier circuit. The method also includes generating the target voltage based on a respective one of a first lookup table, a second lookup table, and a third lookup table under the determined one of the first operating condition, the second operating condition, and the third operating condition.

[0008] In another aspect, a wireless device is provided. The wireless device includes a power management circuit. The power management circuit includes a PMIC. The PMIC is configured to generate a supply voltage based on a target voltage. The power management circuit also includes a power amplifier circuit. The power amplifier circuit includes a first power amplifier activated at all times and a second power amplifier activated conditionally to amplify an RF signal based on the supply voltage. The power amplifier circuit also includes an impedance modulation circuit. The impedance modulation circuit is coupled between a respective output of the first power amplifier and a respective output of the second power amplifier. The power management circuit also includes a transceiver circuit. The transceiver circuit is configured to determine that thepower management circuit is configured to operate under one of a first operating condition, a second operating condition, and a third operating condition based on a modulation bandwidth of the RF signal and a predefined power backoff of the power amplifier circuit. The transceiver circuit is also configured to generate the target voltage based on a respective one of a first lookup table, a second lookup table, and a third lookup table under the determined one of the first operating condition, the second operating condition, and the third operating condition.

[0009] Those skilled in the art will appreciate the scope of the present disclosure and realize additional aspects thereof after reading the following detailed description of the preferred embodiments in association with the accompanying drawing figures.Brief Description of the Drawing Figures

[0010] The accompanying drawing figures incorporated in and forming a part of this specification illustrate several aspects of the disclosure and, together with the description, serve to explain the principles of the disclosure.

[0011] Figure 1 is a schematic diagram of an exemplary power management circuit wherein a transceiver circuit can be configured according to embodiments of the present disclosure to adapt configurations and / or controls for a power management integrated circuit (PMIC) and a power amplifier circuit under different operating conditions;

[0012] Figure 2 is a schematic diagram of an equivalent electrical model of the power amplifier circuit in Figure 1 ;

[0013] Figure 3 is a graphic diagram providing an exemplary illustration as to how the power management circuit of Figure 1 operates under a first operating condition;

[0014] Figure 4 is a graphic diagram providing an exemplary illustration as to how the power management circuit of Figure 1 operates under a second operating condition;

[0015] Figure 5 is a graphic diagram providing an exemplary illustration as to how the power management circuit of Figure 1 operates under a third operating condition;

[0016] Figure 6 is a schematic diagram of an exemplary communication device wherein the power management circuit of Figure 1 can be provided;

[0017] Figure 7 is a flowchart of an exemplary process for operating the power management circuit of Figure 1 under the different operating conditions; and

[0018] Figure 8 is a flowchart of a process further illustrating how the power management circuit of Figure 1 operates under different operating conditions.Detailed Description

[0019] The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the embodiments and illustrate the best mode of practicing the embodiments. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the disclosure and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

[0020] It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of the present disclosure. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0021] It will be understood that when an element such as a layer, region, or substrate is referred to as being "on" or extending "onto" another element, it can be directly on or extend directly onto the other element or intervening elements may also be present. In contrast, when an element is referred to as being"directly on" or extending "directly onto" another element, there are no intervening elements present. Likewise, it will be understood that when an element such as a layer, region, or substrate is referred to as being "over" or extending "over" another element, it can be directly over or extend directly over the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly over" or extending "directly over" another element, there are no intervening elements present. It will also be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element, there are no intervening elements present.

[0022] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" may be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the Figures. It will be understood that these terms and those discussed above are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures.

[0023] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and / or "including" when used herein specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0024] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms used herein should be interpreted as having a meaningthat is consistent with their meaning in the context of this specification and the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0025] Embodiments are described herein with reference to operating a power management circuit based on modulation bandwidth and power backoff. The power management circuit includes a transceiver circuit, a power management integrated circuit (PMIC), and a power amplifier circuit that are configured to amplify a radio frequency (RF) signal for transmission in a wireless device. Herein, the power management circuit can be configured to operate under different operating conditions that are defined by modulation bandwidth of the RF signal and power backoff of the power amplifier circuit. The transceiver circuit is configured to adapt configurations and / or controls for the PMIC and / or the power amplifier circuit based on the different operating conditions. As a result, it is possible to improve power added efficiency (PAE), linearity, and / or noise tolerance in the power management circuit under the different operating conditions.

[0026] Figure 1 is a schematic diagram of an exemplary power management circuit 10 wherein a transceiver circuit 12 can be configured according to embodiments of the present disclosure to adapt configurations and / or controls for a PMIC 14 and a power amplifier circuit 16 under different operating conditions. The transceiver circuit 12 is configured to generate an RF signal 18 having a time-variant input power PIN and a target voltage VTGT that tracks the time-variant input power PIN of the RF signal 18. Herein, the transceiver circuit 12 can modulate the RF signal 18 with a specific modulation bandwidth, which is a frequency range defined by a higher modulation frequency and a lower modulation frequency. In context of the present disclosure, the modulation bandwidth is said to be a higher modulation bandwidth when the modulation bandwidth is greater than a predefined bandwidth threshold (e.g., 20 MHz or 40 MHz), or a lower modulation bandwidth when the modulation bandwidth is lower than or equal to the bandwidth threshold.

[0027] The PMIC 14 is configured to generate a supply voltage Vcc based on the target voltage VTGT. In one embodiment, the PMIC 14 can modulate the supply voltage Vcc as an envelope tracking (ET) voltage to track the time-variant input power PIN of the RF signal 18. In another embodiment, the PMIC 14 can generate the supply voltage Vcc as an average power tracking (APT) voltage in accordance with an average of the time-variant input power PI of the RF signal 18.

[0028] The power amplifier circuit 16 is configured to amplify the RF signal 18 from the time-variant input power PIN to a time-variant output power POUT based on the supply voltage Vcc. Specifically, the power amplifier circuit 16 includes a first power amplifier 20 and a second power amplifier 22. The first power amplifier 20 is active all the time to amplify the RF signal 18 based on the supply voltage Vcc, whereas the second power amplifier 22 is activated conditionally under the different operating conditions.

[0029] The power amplifier circuit 16 further includes an impedance modulation circuit 24, which is coupled between a respective output 26 of the first power amplifier 20 and a respective output 28 of the second power amplifier 22. When the second power amplifier 22 is activated, the impedance modulation circuit 24 is configured to modulate a load impedance ZIN at the respective output 26 of the first power amplifier 20. In an embodiment, the impedance modulation circuit 24 can be configured to receive a load modulation signal 30 from the PMIC 14 and modulate the load impedance ZIN to a specific value as indicated in the load modulation signal 30. When the second power amplifier 22 is deactivated under a specific operating condition, the impedance modulation circuit 24 will stop modulating the load impedance ZIN. Instead, the impedance modulation circuit 24 will present the load impedance ZIN at the respective output 26 with a higher fixed value (e.g., 4-times the load line impedance).

[0030] The impedance modulation circuit 24 can be configured to modulate the load impedance ZI as a function of a load impedance ZL presented by a load circuit 31 (e.g., an RF frontend circuit) configured to receive the RF signal 18from the power amplifier circuit 16. Specifically, the load impedance ZIN can be expressed in equation (Eq. 1 ) below.ZIN = K2 / ZL (Eq. 1 )

[0031] In the equation (Eq. 1 ), K represents a configurable modulation term of the impedance modulation circuit 24, which can be manipulated based on the load modulation signal 30 to change the load impedance ZIN. For an in-depth description as to how the PMIC 14 can generate the load modulation signal 30 and how the impedance modulation circuit 24 can modulate the load impedance ZI , please refer to U.S. Patent Application Number 19 / 274,857, filed on July 21 , 2025, and entitled “DYNAMIC IMPEDANCE MODULATION IN A POWER MANAGEMENT CIRCUIT.”

[0032] The operating principles of the power amplifier circuit 16 can be further explained based on an equivalent electrical model of the power amplifier circuit 16. In this regard, Figure 2 is a schematic diagram of an equivalent electrical model 32 of the power amplifier circuit 16 in Figure 1 . Common elements between Figures 1 and 2 are shown therein with common element numbers and will not be re-described herein.

[0033] In the equivalent electrical model 32, each of the first power amplifier 20 and the second power amplifier 22 is modeled as a current source. The first power amplifier 20 is coupled to a first load-line transfer function 34 and the second power amplifier 22 is coupled to a second load-line transfer function 36. In a non-limiting example, each of the first load-line transfer function 34 and the second load-line transfer function 36 can be a transformer. For the sake of simplicity, each of the first load-line transfer function 34 and the second load-line transfer function 36 is assumed to be equal to one (1 ).

[0034] Before the second power amplifier 22 is activated, the first power amplifier 20 will generate a first current IM to thereby amplify the RF signal 18 from the time-variant input power PIN to the time-variant output power POUT. When the load circuit 31 , which has an inherent impedance ZL, receives the RFsignal 18, the load circuit 31 produces the load current ILOAD. Since the second power amplifier 22 is inactive, the load current ILOAD is thus identical to another load current I’LOAD that flows into the impedance modulation circuit 24. As such, the first power amplifier 20 sees a first voltage VM (VM = K*I’LOAD).

[0035] When the second power amplifier 22 is activated, the second power amplifier 22 will generate a second current j* Ip to thereby further amplify the RF signal 18 from the time-variant input power PIN to the time-variant output power POUT. AS such, the load current ILOAD will now equal a sum of the load current I’LOAD and the second current IP (ILOAD = I’LOAD + j*lp). As such, the second power amplifier 22 sees a second voltage Vp (Vp = -J*K*IM).

[0036] With reference back to Figure 1 , the power amplifier circuit 16 can include a control circuit 38, a peak detector 40, and a phase shifter 42. The peak detector 40 is configured to detect the instantaneous power level of the RF signal 18. The phase shifter 42 is configured to provide a negative ninety-degree (-90°) phase shift of the RF signal 18 for the second power amplifier 22. The control circuit 38 receives the load modulation signal 30 from the PMIC 14 and the detected instantaneous power level of the RF signal 18. Accordingly, the control circuit 38 can bias the first power amplifier 20 and / or the second power amplifier 22 via a bias signal 44. As an example, the control circuit 38 can use the bias signal 44 to activate or deactivate the second power amplifier 22 as needed.

[0037] In an embodiment, the PMIC 14 includes a current generation circuit 46, a voltage amplifier 48, and an offset capacitor COFF. The current generation circuit 46, which includes a multi-level voltage converter (MCP) 50 coupled in series to a power inductor 52, is configured to generate a low-frequency current IDC as a function of a battery voltage VBAT. The voltage amplifier 48 is biased by a bias voltage VSUP to generate an initial supply voltage VAMP that tracks (increases and decreases) the target voltage VTGT. The offset capacitor COFF is configured to raise the initial supply voltage VAMP by an offset voltage VOFF to thereby generate the supply voltage Vcc (Vcc = VAMP + VOFF). Understandably, the PMIC 14 can include additional circuits, such as a feedback loop and a local controller, which are omitted herein for the sake of simplicity.

[0038] In embodiments disclosed herein, the power management circuit 10 may operate under a first operating condition when the modulation bandwidth of the RF signal 18 is higher than the bandwidth threshold and the power amplifier circuit 16 is configured to operate based on a predefined power backoff that is higher than a backoff threshold (e.g., 6 dB). The power management circuit 10 may also operate under a second operating condition when the modulation bandwidth of the RF signal 18 is higher than the bandwidth threshold and the power amplifier circuit 16 is configured to operate based on the predefined power backoff that is lower than or equal to the backoff threshold. The power management circuit 10 may further operate under a third operating condition when the modulation bandwidth of the RF signal 18 is lower than or equal to the bandwidth threshold.

[0039] Understandably, since the RF signal 18 is generated by the transceiver circuit 12, the transceiver circuit 12 will have a first-hand knowledge of the modulation bandwidth of the RF signal 18 and the power backoff of the power amplifier circuit 16. As such, the transceiver circuit 12 can determine which of the first operating condition, the second operating condition, and the third operating condition the power management circuit 10 will be operating under. Accordingly, the transceiver circuit 12 can effectively configure and / or control the PMIC 14 and the power amplifier circuit 16 under the different operating conditions to help improve PAE, linearity, and noise tolerance of the voltage amplifier 48, the first power amplifier 20, and / or the second power amplifier 22 in the power management circuit 10.

[0040] In an embodiment, the transceiver circuit 12 may configure the PMIC 14 via the target voltage VTGT and control the control circuit 38 in the power amplifier circuit 16 via a control signal 54. Specifically, the transceiver circuit 12 can be configured to determine the target voltage VTGT based on a set of lookup tables (LUTs) LUT-1 (a.k.a. “first lookup table”), LUT-2 (a.k.a. “second lookup table”), and LUT-3 (a.k.a. “third lookup table”), each of which is predefined and calibrated to correlate the time-variant input power PIN of the RF signal 18 with a respective set of values of the target voltage VTGT under a respective one of thefirst operating condition, the second operating condition, and the third operating condition.

[0041] Figure 3 is a graphic diagram providing an exemplary illustration as to how the power management circuit 10 of Figure 1 operates under the first operating condition. Common elements between Figures 1 and 3 are shown therein with common element numbers and will not be re-described herein.

[0042] As described earlier, the power management circuit 10 will operate under the first operating condition when the modulation bandwidth of the RF signal 18 is higher than the bandwidth threshold (e.g., 20 MHz) and a predefined power backoff PBACKOFF of the power amplifier circuit 16 is higher than the backoff threshold (e.g., 6 dB). Herein, the predefined power backoff PBACKOFF refers to a difference between a maximum peak power PPEAK-MAX and a backoff maximum peak power PPEAK-BACK of the RF signal 18 ( PBACKOFF = PPEAK-MAX - PPEAK-BACK).

[0043] In an embodiment, when the transceiver circuit 12 determines that the power management circuit is operating under the first operating condition, the transceiver circuit 12 will generate the target voltage VTGT based on the first lookup table LLIT-1 and provide the control signal 54 to the control circuit 38 to deactivate the second power amplifier 22 in the power amplifier circuit 16. As such, the impedance modulation circuit 24 will stop modulating the load impedance ZIN. Instead, the impedance modulation circuit 24 will present the load impedance ZI at four times (4x) the load line.

[0044] In this regard, the power amplifier circuit 16 will operate based solely on the supply voltage Vcc (a.k.a. “supply modulation”). In other words, the offset voltage VOFF can be set to a constant value, whereas the initial supply voltage VAMP is modulated in accordance with the target voltage VTGT.

[0045] Herein, the first lookup table LUT-1 can be defined to help improve PAE under the first operating condition. Moreover, given the larger power backoff, the PMIC 14 will generate the supply voltage Vcc in accordance with the backoff maximum peak power PPEAK-BACK instead of the maximum peak power PPEAK-MAX.

[0046] Figure 4 is a graphic diagram providing an exemplary illustration as to how the power management circuit 10 of Figure 1 operates under the second operating condition. Common elements between Figures 1 and 4 are shown therein with common element numbers and will not be re-described herein.

[0047] As described earlier, the power management circuit 10 will operate under the second operating condition when the modulation bandwidth of the RF signal 18 is higher than the bandwidth threshold (e.g., 20 MHz) and the predefined power backoff PBACKOFF of the power amplifier circuit 16 is lower than or equal to the backoff threshold (e.g., 6 dB). Again, the predefined power backoff PBACKOFF refers to the difference between the maximum peak power PPEAK-MAX and the backoff maximum peak power PPEAK-BACK of the RF signal 18 (PBACKOFF = PPEAK-MAX - P PEAK-BACK).

[0048] Herein, the power amplifier circuit 16 is configured to operate based on a first power threshold Po and a second power threshold Pi, which are both lower than one-half of a peak power threshold PMAX (PO <1 / 2 PMAX and Pi <1 / 2 PMAX). More specifically, the first power threshold Po can be 10 to 16 dB below the peak power level PMAX and the first power threshold Po is less than one-half (1 / z) of the second power threshold Pi (Po < 2P1).

[0049] Herein, the supply voltage Vcc increases and the first power amplifier 20 delivers the first current IM when an instantaneous power level of the RF signal 18 is below the first power threshold Po. As previously discussed in Figure 2, the first power amplifier 20 will drive the load current ILOAD using the first current IM. When the instantaneous power level of the RF signal 18 is above the first power threshold Po, the second power amplifier 22 is activated. As discussed in Figure 2, the second power amplifier 22 will increase the load current ILOAD needed to drive the time-variant output power POUT toward the peak power level PMAX using the second current j*lp.

[0050] Should the first power threshold Po be set to one-half (1 / z) of the second power threshold Pi (Po = 2P1), the supply voltage Vcc would be maintained constantly at the minimum supply voltage VCC-MIN when the instantaneous power level of the RF signal 18 is lower than or equal to the first power threshold Po. Inthis regard, the supply voltage Vcc will be confined to a voltage range VCC-RANGE as defined by the maximum supply voltage VCC-MAX and the minimum supply voltage VCC- IN (VCC-RANGE = VCC-MAX - VCC-MIN). In contrast, when the first power threshold Po is less than one-half ( 2) of the second power threshold Pi (Po < 72P1), the second current j*lp delivered by the second power amplifier 22 will not make up for the additional current needed to drive the instantaneous power level of the RF signal 18 toward the peak power level PMAX. AS a result, the supply voltage Vcc will increase gradually from a lowered minimum supply voltage V’cc- MIN (V’CC-MIN < VCC-MI ) between the first power threshold Po and the second power threshold Pi. As such, instead of operating solely based on load modulation, the power amplifier circuit 16 will operate based on a combination of load modulation and supply modulation until the instantaneous power level becomes higher than the second power threshold Pi.

[0051] When the instantaneous power level of the RF signal 18 becomes higher than the second power threshold Pi, the supply voltage Vcc will continue to increase until reaching the maximum supply voltage V’CC-MAX at the peak power level PPEAK-BACK. Herein, each of the first power amplifier 20 and the second power amplifier 22 will see an identical load line and deliver one half ( 2) of the time-variant output power POUT.

[0052] Notably, when the supply voltage Vcc is an ET voltage modulated according to the target voltage VTGT, the first power amplifier 20 will be in full compression between the first power threshold Po and the peak power level PPEAK-BACK, whereas the second power amplifier 22 is in full compression between the second power threshold Pi and the peak power level PPEAK-BACK. AS such, the power amplifier circuit 16 can achieve an improved PAE.

[0053] In an embodiment, when the transceiver circuit 12 determines that the power management circuit 10 is operating under the second operating condition, the transceiver circuit 12 will generate the target voltage VTGT based on the second lookup table LUT-2, and provide the control signal 54 to the control circuit 38 to activate the second power amplifier 22 when the instantaneous power level of the RF signal 18 is higher than the first power threshold Po, and deactivate thesecond power amplifier 22 when the instantaneous power level of the RF signal 18 is lower than or equal to the first power threshold Po.

[0054] When the second power amplifier 22 is deactivated, the impedance modulation circuit 24 will stop modulating the load impedance ZIN but will present the load impedance ZIN at four times (4x) the load line. Below the second power threshold Po, neither supply modulation nor load modulation is used. Since the power amplifier circuit 16 operates without modulation below the first power threshold Po and operates with supply modulation above the second power threshold Pi, the second power amplifier 22 is so biased when the instantaneous power level of the RF signal 18 is below the first power threshold Po to have an identical isogain as in the second lookup table LUT-2 when the instantaneous power level of the RF signal 18 is above the second power threshold Pi.

[0055] In one embodiment, the first lookup table LLIT-1 and the second lookup table LUT-2 can be separate lookup tables. Since the first lookup table LUT-1 corresponds to a larger power backoff compared to the second lookup table LUT- 2, the first lookup table LUT-1 can be configured to have fewer calibration points than the second lookup table LUT-2.

[0056] In an alternative embodiment, the first lookup table LUT-1 can be a subset of the second lookup table LUT-2. As an example, the second lookup table LUT-2 can be configured to correspond to multiple power backoff values. Each of the power backoff values can be associated with a respective set of the first power threshold Po and the second power threshold Pi. As such, when the power amplifier circuit 16 is configured to operate based on a specific one of the power backoff values, the transceiver circuit 12 can then select a corresponding subset of the calibration points (e.g., by setting different tapping points) from the second lookup table LUT-2 to use as the first lookup table LUT-1 .

[0057] One important aspect of the second lookup table LUT-2 is that the isogain should be identical below the respective first power threshold Po and above the respective second power threshold Pi for each of the power backoff values. In addition, the respective set of the maximum supply voltage VCC-MAX, the minimum supply voltage CC-MIN, the first power threshold Po and the secondpower threshold Pi can be adjusted (e.g., scaled) for each of the power backoff values.

[0058] Figure 5 is a graphic diagram providing an exemplary illustration as to how the power management circuit 10 of Figure 1 operates under the third operating condition. Common elements between Figures 1 and 5 are shown therein with common element numbers and will not be re-described herein.

[0059] As described earlier, the power management circuit 10 will operate under the third operating condition when the modulation bandwidth of the RF signal 18 is lower than or equal to the bandwidth threshold (e.g., 20 MHz). When the transceiver circuit 12 determines that the power management circuit 10 is configured to operate under the third operating condition, the transceiver circuit 12 will generate the target voltage VTGT based on the third lookup table LUT-3, which is preconfigured to offset amplitude-amplitude (AM-AM) and amplitudephase (AM-PM) variations in the supply voltage Vcc to thereby improve noise tolerance of the power management circuit 10. Under the third operating condition, the transceiver circuit will also activate the second power amplifier 22. Further, the transceiver circuit 12 can use the control signal 54 to cause the control circuit 38 to equally bias the first power amplifier 20 and the second power amplifier 22.

[0060] The power management circuit 10 of Figure 1 can be provided in a communication device to support the embodiments described above. In this regard, Figure 6 is a schematic diagram of an exemplary communication device 100 wherein the power management circuit 10 of Figure 1 can be provided.

[0061] Herein, the communication device 100 can be any type of communication devices, such as mobile terminals, smart watches, tablets, computers, navigation devices, access points, base stations (e.g., eNB, gNB, etc.), and like wireless communication devices that support wireless communications, such as cellular, wireless local area network (WLAN), Ultra- wideband (UWB), Bluetooth, and near-field communications. The communication device 100 will generally include a control system 102, a baseband processor 104, transmit circuitry 106, receive circuitry 108, antenna switching circuitry 1 10,multiple antennas 1 12, and user interface circuitry 114. In a non-limiting example, the control system 102 can be a field-programmable gate array (FPGA), as an example. In this regard, the control system 102 can include at least a microprocessor, an embedded memory circuit, and a communication bus interface. The receive circuitry 108 receives radio frequency signals via the antennas 1 12 and through the antenna switching circuitry 110 from one or more base stations. A low-noise amplifier and a filter cooperate to amplify and remove broadband interference from the received signal for processing.Downconversion and digitization circuitry (not shown) will then downconvert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams using analog-to-digital converters (ADCs).

[0062] The baseband processor 104 processes the digitized received signal to extract the information or data bits conveyed in the received signal. This processing typically comprises demodulation, decoding, and error correction operations, as will be discussed in greater detail below. The baseband processor 104 is generally implemented in one or more digital signal processors (DSPs) and application-specific integrated circuits (ASICs).

[0063] For transmission, the baseband processor 104 receives digitized data, which may represent voice, data, or control information, from the control system 102, which it encodes for transmission. The encoded data is output to the transmit circuitry 106, where a digital-to-analog converter (DAC) converts the digitally encoded data into an analog signal and a modulator modulates the analog signal onto a carrier signal that is at a desired transmit frequency or frequencies. A power amplifier will amplify the modulated carrier signal to a level appropriate for transmission and deliver the modulated carrier signal to the antennas 1 12 through the antenna switching circuitry 110. The multiple antennas 1 12 and the replicated transmit 106 and receive circuitry 108 may provide spatial diversity. Modulation and processing details will be understood by those skilled in the art.

[0064] In an embodiment, the transmit circuitry 106 and the receive circuitry 108 can function as the transceiver circuit 12 in Figure 1 . Accordingly, the PMIC 14 and the power amplifier circuit 16 can be provided between the transmit circuitry 106 and the antenna switching circuitry 1 10.

[0065] In an embodiment, the power management circuit 10 of Figure 1 can be operated in accordance with a process. In this regard, Figure 7 is a flowchart of an exemplary process 200 for operating the power management circuit 10 of Figure 1 based on modulation bandwidth and power backoff.

[0066] Herein, the process 200 includes generating the supply voltage Vcc based on the target voltage VTGT (step 202). The process 200 also includes activating the first power amplifier 20 in the power amplifier circuit 16 at all times and activating the second power amplifier 22 in the power amplifier circuit 16 conditionally to amplify the RF signal 18 based on the supply voltage Vcc (step 204). The process 200 also includes determining that the power management circuit 10 is configured to operate under one of the first operating condition, the second operating condition, and the third operating condition based on the modulation bandwidth of the RF signal 18 and the predefined power backoff of the power amplifier circuit 16 (step 206). The process 200 also includes generating the target voltage VTGT based on a respective one of the first lookup table LUT-1 , the second lookup table LUT-2, and the third lookup table LUT-3 under the determined one of the first operating condition, the second operating condition, and the third operating condition (step 208).

[0067] Figure 8 is a flowchart of a process 300 further illustrating how the power management circuit 10 of Figure 1 operates under different operating conditions. Herein, the power management circuit 10 can first check to see whether the modulation bandwidth of the RF signal is below the bandwidth threshold and whether low noise and / or high linearity is required (step 302). If so, the power management circuit 10 will activate both the first power amplifier 20 and the second power amplifier 22 and operate based on the third lookup table LUT-3 (step 304). If not, the power management circuit 10 will further check whether the predefined power backoff PBACKOFF (a.k.a. peak backoffpower) is below the backoff threshold (step 306). If so, the power management circuit 10 will activate the first power amplifier 20 at all times and activate the second power amplifier 22 conditionally and operate based on the second lookup table LLIT-2 (step 308). In case the predefined power backoff PBACKOFF is above the backoff threshold, the power management circuit 10 will activate the first power amplifier 20, deactivate the second power amplifier 22, and operate based on the first lookup table LUT-1 (step 310). Alternatively, the power management circuit 10 may also activate the first power amplifier 20 at all times and activate the second power amplifier 22 conditionally. Accordingly, the power management circuit 10 may operate based on the second lookup table LUT-2 but scale the maximum supply voltage VCC-MAX, the minimum supply voltage VCC-MIN, the first power threshold Po, and the second power threshold Pi for each of the power backoff values.

[0068] Those skilled in the art will recognize improvements and modifications to the preferred embodiments of the present disclosure. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

Claims

ClaimsWhat is claimed is:1 . A power management circuit comprising: a power management integrated circuit (PMIC) configured to generate a supply voltage based on a target voltage; a power amplifier circuit comprising: a first power amplifier activated at all times and a second power amplifier activated conditionally to amplify a radio frequency (RF) signal based on the supply voltage; and an impedance modulation circuit coupled between a respective output of the first power amplifier and a respective output of the second power amplifier; and a transceiver circuit configured to: determine that the power management circuit is configured to operate under one of a first operating condition, a second operating condition, and a third operating condition based on a modulation bandwidth of the RF signal and a predefined power backoff of the power amplifier circuit; and generate the target voltage based on a respective one of a first lookup table, a second lookup table, and a third lookup table under the determined one of the first operating condition, the second operating condition, and the third operating condition.

2. The power management circuit of claim 1 , wherein the transceiver circuit is further configured to: determine that the power management circuit is configured to operate under the first operating condition wherein the modulation bandwidth is higher than a bandwidth threshold and the predefined power backoff is higher than a backoff threshold; andgenerate the target voltage based on the first lookup table and deactivate the second power amplifier.

3. The power management circuit of claim 1 , wherein the transceiver circuit is further configured to: determine that the power management circuit is configured to operate under the second operating condition wherein the modulation bandwidth is higher than a bandwidth threshold and the predefined power backoff is lower than or equal to a backoff threshold; generate the target voltage based on the second lookup table; activate the second power amplifier when an instantaneous power level of the RF signal is higher than a first power threshold that is below one-half of a peak power level of the RF signal; and deactivate the second power amplifier when the instantaneous power level of the RF signal is lower than or equal to the first power threshold.

4. The power management circuit of claim 3, wherein the impedance modulation circuit is configured to: modulate a load impedance at the respective output of the first power amplifier when the instantaneous power level of the RF signal is higher than the first power threshold but lower than a second power threshold that is also below one-half of the peak power level of the RF signal; and stop modulating the load impedance when the instantaneous power level of the RF signal is higher than or equal to the second power threshold.

5. The power management circuit of claim 4, wherein each of the first power amplifier and the second power amplifier is further configured to amplify the RF signal to one-half of the instantaneous power level when the instantaneouspower level of the RF signal is higher than or equal to the second power threshold.

6. The power management circuit of claim 4, wherein: the second power threshold is less than two times the first power threshold; and the PMIC is further configured to increase the supply voltage when the instantaneous power level of the RF signal is between the first power threshold and the second power threshold.

7. The power management circuit of claim 4, wherein the second power amplifier is biased when the instantaneous power level of the RF signal is below the first power threshold to have an identical isogain as in the second lookup table when the instantaneous power level of the RF signal is above the second power threshold.

8. The power management circuit of claim 3, wherein the first lookup table is separate from the second lookup table and comprises fewer calibration points than the second lookup table.

9. The power management circuit of claim 3, wherein the first lookup table is a subset of the second lookup table.

10. The power management circuit of claim 1 , wherein the transceiver circuit is further configured to: determine that the power management circuit is configured to operate under the third operating condition wherein the modulation bandwidth of the RF signal is lower than or equal to a bandwidth threshold; and generate the target voltage based on the third lookup table and activate the second power amplifier.1 1. A method for operating a power management circuit based on modulation bandwidth and power backoff comprising: generating a supply voltage based on a target voltage; activating a first power amplifier in a power amplifier circuit at all times and activating a second power amplifier in the power amplifier circuit conditionally to amplify a radio frequency (RF) signal based on the supply voltage; determining that the power management circuit is configured to operate under one of a first operating condition, a second operating condition, and a third operating condition based on the modulation bandwidth of the RF signal and a predefined power backoff of the power amplifier circuit; and generating the target voltage based on a respective one of a first lookup table, a second lookup table, and a third lookup table under the determined one of the first operating condition, the second operating condition, and the third operating condition.

12. The method of claim 11 , further comprising: determining that the power management circuit is configured to operate under the first operating condition wherein the modulation bandwidth is higher than a bandwidth threshold and the predefined power backoff is higher than a backoff threshold; and generating the target voltage based on the first lookup table and deactivating the second power amplifier.

13. The method of claim 11 , further comprising: determining that the power management circuit is configured to operate under the second operating condition wherein the modulation bandwidth of the RF signal is higher than a bandwidth threshold and the predefined power backoff is lower than or equal to a backoff threshold;generating the target voltage based on the second lookup table; activating the second power amplifier when an instantaneous power level of the RF signal is higher than a first power threshold that is below one-half of a peak power level of the RF signal; and deactivating the second power amplifier when the instantaneous power level of the RF signal is lower than or equal to the first power threshold.

14. The method of claim 13, further comprising: modulating a load impedance at a respective output of the first power amplifier when the instantaneous power level of the RF signal is higher than the first power threshold but lower than a second power threshold that is also below one-half of the peak power level of the RF signal; and stopping modulation of the load impedance when the instantaneous power level of the RF signal is higher than or equal to the second power threshold.

15. The method of claim 11 , further comprising: determining that the power management circuit is configured to operate under the third operating condition wherein the modulation bandwidth of the RF signal is lower than or equal to a bandwidth threshold; and generating the target voltage based on the third lookup table and activating the second power amplifier.

16. A wireless device comprising a power management circuit, the power management circuit comprises: a power management integrated circuit (PMIC) configured to generate a supply voltage based on a target voltage; a power amplifier circuit comprising:a first power amplifier activated at all times and a second power amplifier activated conditionally to amplify a radio frequency (RF) signal based on the supply voltage; and an impedance modulation circuit coupled between a respective output of the first power amplifier and a respective output of the second power amplifier; and a transceiver circuit configured to: determine that the power management circuit is configured to operate under one of a first operating condition, a second operating condition, and a third operating condition based on a modulation bandwidth of the RF signal and a predefined power backoff of the power amplifier circuit; and generate the target voltage based on a respective one of a first lookup table, a second lookup table, and a third lookup table under the determined one of the first operating condition, the second operating condition, and the third operating condition.

17. The wireless device of claim 16, wherein the transceiver circuit is further configured to: determine that the power management circuit is configured to operate under the first operating condition wherein the modulation bandwidth is higher than a bandwidth threshold and the predefined power backoff is higher than a backoff threshold; and generate the target voltage based on the first lookup table and deactivate the second power amplifier.

18. The wireless device of claim 16, wherein the transceiver circuit is further configured to: determine that the power management circuit is configured to operate under the second operating condition wherein the modulationbandwidth of the RF signal is higher than a bandwidth threshold and the predefined power backoff is lower than or equal to a backoff threshold; generate the target voltage based on the second lookup table; activate the second power amplifier when an instantaneous power level of the RF signal is higher than a first power threshold that is below one-half of a peak power level of the RF signal; and deactivate the second power amplifier when the instantaneous power level of the RF signal is lower than or equal to the first power threshold.

19. The wireless device of claim 18, wherein the impedance modulation circuit is configured to: modulate a load impedance at the respective output of the first power amplifier when the instantaneous power level of the RF signal is higher than the first power threshold but lower than a second power threshold that is also below one-half of the peak power level of the RF signal; and stop modulating the load impedance when the instantaneous power level of the RF signal is higher than or equal to the second power threshold.

20. The wireless device of claim 16, wherein the transceiver circuit is further configured to: determine that the power management circuit is configured to operate under the third operating condition wherein the modulation bandwidth of the RF signal is lower than or equal to a bandwidth threshold; and generate the target voltage based on the third lookup table and activate the second power amplifier.

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