Multi-bandwidth envelope tracking integrated circuit and related apparatus

A multi-bandwidth envelope tracking (ET) integrated circuit (IC) (ETIC) and related apparatus are provided. In a non-limiting example, the multi-bandwidth ETIC is coupled to an amplifier circuit(s) configured to amplify a radio frequency (RF) signal corresponding to a wide range of modulation bandwidth (e.g., from less than 90 KHz to over 40 MHz). In this regard, the multi-bandwidth ETIC is configured to generate different ET voltages based on the modulation bandwidth of the RF signal. By generating the ET voltages based on the modulation bandwidth of the RF signal, it may be possible to optimize operating efficiency of the amplifier circuit(s). As a result, it may be possible to improve power consumption and reduce heat dissipation in an apparatus employing the multi-bandwidth ETIC, thus making it possible to provide the multi-bandwidth ETIC in a wearable device.

FIELD OF THE DISCLOSURE

The technology of the disclosure relates generally to an envelope tracking (ET) radio frequency (RF) power amplifier apparatus.

BACKGROUND

Mobile communication devices, such as smartphones, 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.

The redefined user experience has also led to the rise of so-called wearable devices, such as smartwatches. Over time, these wearable devices have evolved from simple companion devices to mobile communication devices into full-fledged multi-functional wireless communication devices. Nowadays, most wearable electronic devices are often equipped with digital and analog circuitries capable of communicating a radio frequency (RF) signal(s) in a variety of wireless communication systems, such as long-term evolution (LTE), Wi-Fi, Bluetooth, and so on. Like mobile communication devices, wearable devices often employ sophisticated power amplifiers to amplify RF signal(s) to help improve coverage range, data throughput, and reliability of the wearable devices.

Envelope tracking (ET) is a power management technology designed to improve efficiency levels of power amplifiers. In this regard, it may be desirable to employ ET across a variety of wireless communication technologies to help reduce power consumption and thermal dissipation in wearable devices. Notably, the RF signal(s) communicated in different wireless communication systems may correspond to different modulation bandwidths (e.g., from 80 KHz to over 40 MHz). As such, it may be further desirable to ensure that the power amplifiers can maintain optimal efficiency across a wide range of modulation bandwidth.

SUMMARY

Embodiments of the disclosure relate to a multi-bandwidth envelope tracking (ET) integrated circuit (IC) (ETIC) and related apparatus. In a non-limiting example, the multi-bandwidth ETIC is coupled to an amplifier circuit(s) configured to amplify a radio frequency (RF) signal corresponding to a wide range of modulation bandwidth (e.g., from less than 90 KHz to over 40 MHz). In this regard, the multi-bandwidth ETIC is configured to generate different ET voltages based on the modulation bandwidth of the RF signal. By generating the ET voltages based on the modulation bandwidth of the RF signal, it may be possible to optimize operating efficiency of the amplifier circuit(s). As a result, it may be possible to improve power consumption and reduce heat dissipation in an apparatus employing the multi-bandwidth ETIC, thus making it possible to provide the multi-bandwidth ETIC in a wearable device.

In one aspect, a multi-bandwidth ETIC is provided. The multi-bandwidth ETIC includes an output port coupled to an amplifier circuit configured to amplify an RF signal based on a modulated voltage. The multi-bandwidth ETIC also includes a first ET voltage circuit configured to generate a first ET voltage corresponding to a first modulation bandwidth. The multi-bandwidth ETIC also includes a second ET voltage circuit configured to generate a second ET voltage corresponding to a second modulation bandwidth lower than the first modulation bandwidth. The multi-bandwidth ETIC also includes a control circuit. The control circuit is configured to activate the first ET voltage circuit and deactivate the second ET voltage circuit to provide the first ET voltage to the output port as the modulated voltage in response to the RF signal being modulated in the first modulation bandwidth. The control circuit is also configured to activate the second ET voltage circuit and deactivate the first ET voltage circuit to provide the second ET voltage to the output port as the modulated voltage in response to the RF signal being modulated in the second modulation bandwidth.

In another aspect, an ET apparatus is provided. The ET apparatus includes an amplifier circuit configured to amplify an RF signal based on a modulated voltage. The ET apparatus also includes a multi-bandwidth ETIC. The multi-bandwidth ETIC includes an output port coupled to the amplifier circuit.

The multi-bandwidth ETIC also includes a first ET voltage circuit configured to generate a first ET voltage corresponding to a first modulation bandwidth. The multi-bandwidth ETIC also includes a second ET voltage circuit configured to generate a second ET voltage corresponding to a second modulation bandwidth lower than the first modulation bandwidth. The multi-bandwidth ETIC also includes a control circuit. The control circuit is configured to activate the first ET voltage circuit and deactivate the second ET voltage circuit to provide the first ET voltage to the output port as the modulated voltage in response to the RF signal being modulated in the first modulation bandwidth. The control circuit is also configured to activate the second ET voltage circuit and deactivate the first ET voltage circuit to provide the second ET voltage to the output port as the modulated voltage in response to the RF signal being modulated in the second modulation bandwidth.

DETAILED DESCRIPTION

Embodiments of the disclosure relate to a multi-bandwidth envelope tracking (ET) integrated circuit (IC) (ETIC) and related apparatus. In a non-limiting example, the multi-bandwidth ETIC is coupled to an amplifier circuit(s) configured to amplify a radio frequency (RF) signal corresponding to a wide range of modulation bandwidth (e.g., from less than 90 KHz to over 40 MHz). In this regard, the multi-bandwidth ETIC is configured to generate different ET voltages based on the modulation bandwidth of the RF signal. By generating the ET voltages based on the modulation bandwidth of the RF signal, it may be possible to optimize operating efficiency of the amplifier circuit(s). As a result, it may be possible to improve power consumption and reduce heat dissipation in an apparatus employing the multi-bandwidth ETIC, thus making it possible to provide the multi-bandwidth ETIC in a wearable device.

Before discussing the multi-bandwidth ETIC of the present disclosure, a brief overview of a resource block (RB)-based resource allocation scheme is first provided with referenceFIG. 1to help understand the relationship between a modulation bandwidth of an RF signal and a number of RBs allocated to the RF signal. The discussion of specific exemplary aspects of a multi-bandwidth ETIC of the present disclosure starts below with reference toFIG. 2.

In this regard,FIG. 1is a schematic diagram of an exemplary orthogonal frequency division multiplexing (OFDM) time-frequency grid10illustrating at least one RB12. The OFDM time-frequency grid10includes a frequency axis14and a time axis16. Along the frequency axis14, there are a number of subcarriers18(1)-18(M). The subcarriers18(1)-18(M) are orthogonally separated from each other by a frequency spacing Δf of 15 KHz.

Along the time axis16, there are a number of OFDM symbols20(1)-20(N). Each intersection of the subcarriers18(1)-18M) and the OFDM symbols20(1)-20(N) defines a resource element (RE)21.

In one example, the RB12includes twelve (12) consecutive subcarriers among the subcarriers18(1)-18(M), and seven (7) consecutive OFDM symbols among the OFDM symbols20(1)-20(N). In this regard, the RB12includes eighty-four (84) of the REs21(12 subcarriers×7 OFDM symbols). The RB12has an RB duration22, which equals one-half millisecond (0.5 ms), along the time axis16. Accordingly, the RB12has a bandwidth24, which equals 180 KHz (15 KHz/subcarrier×12subcarriers), along the frequency axis14. In OFDM-based communication systems such as long-term evolution (LTE), the RB12is the minimum unit for allocating resources to users.

In an LTE system, an RF signal26can occupy multiple subcarriers among the subcarriers18(1)-18(N). In this regard, a signal bandwidth28of the RF signal26is a function of the number of RBs12contained in the RF signal26along the frequency axis14. In this regard, if the RF signal26contains ten (10) RBs12, then the signal bandwidth28will be 1.8 MHz (180 KHz/RB×10 RBs). If the RF signal26contains twenty-five (25) RBs12, then the signal bandwidth28will be 4.5 MHz (180 KHz/RB×25 RBs). If the RF signal26contains two hundred (200) RBs12, then the signal bandwidth28will be 36 MHz (180 KHz/RB×200 RBs). In this regard, the more RBs12the RF signal26contains, the wider the signal bandwidth28will be, and the more subcarriers among the subcarriers18(1)-18(M) are modulated within the RB duration22. As such, the RF signal26can exhibit more and faster amplitude variations within the RB duration22when the RF signal26is modulated according to a selected modulation and coding scheme (MCS). As a result, when the RF signal26is amplified for transmission over a wireless medium, an ET amplifier circuit would need to operate fast enough to keep up with the faster amplitude variations of the RF signal26across the signal bandwidth28within the RB duration22.

FIG. 2is a schematic diagram of an exemplary ET apparatus30configured according to an embodiment of the present disclosure to incorporate a multi-bandwidth ETIC32for improving operating efficiency of an amplifier circuit34across a wide range of modulation bandwidth. The amplifier circuit34is configured to amplify an RF signal36based on a modulated voltage VCCand the multi-bandwidth ETIC32is configured to generate the modulated voltage VCCbased on modulation bandwidth of the RF signal36. In examples discussed herein, the multi-bandwidth ETIC32can be configured to generate a first ET voltage VCC-Hwhen the RF signal36corresponds to a first modulation bandwidth (e.g., greater than 180 KHz or 1 RB) or a second ET voltage VCC-L(VCC-L<VCC-H) when the RF signal36corresponds to a second modulation bandwidth (e.g., approximately equals 180 KHz or 1 RB). In addition, the multi-bandwidth ETIC32can be further configured to generate a modulated average power tracking (APT) voltage VAPT-Mwhen the RF signal36corresponds to a third modulation bandwidth (e.g., lesser than 90 KHz or ½ RB). The multi-bandwidth ETIC32may be further configured to generate an APT voltage VAPTregardless of the modulation bandwidth of the RF signal36. Accordingly, the amplifier circuit34may receive the first ET voltage VCC-H, the second ET voltage VCC-L, the modulated APT voltage VAPT-M, or the APT voltage VAPTas the modulated voltage VCCfor amplifying the RF signal36. As such, it may be possible to keep the amplifier circuit34in a higher operating efficiency across a wide range of modulation bandwidth. As a result, it may be possible to improve power consumption and heat dissipation of the ET apparatus30, thus making it possible to provide the ET apparatus30in a wearable device.

The multi-bandwidth ETIC32includes an output port38coupled to the amplifier circuit34. The output port38is configured to selectively output one of the first ET voltage VCC-H, the second ET voltage VCC-L, the modulated APT voltage VAPTM, and the APT voltage VAPTas the modulated voltage VCCto the amplifier circuit34for amplifying the RF signal36.

The multi-bandwidth ETIC32includes a first ET voltage circuit40and a second ET voltage circuit42configured to generate the first ET voltage VCC-Hand the second ET voltage VCC-Lat the output port38, respectively. The multi-bandwidth ETIC32includes a tracker circuit44configured to generate the modulate APT voltage VAPTMand the APT voltage VAPT.

In a non-limiting example, the first ET voltage circuit40includes a first voltage amplifier46(denoted as “AMP-H”) and a first offset capacitor48, and the second ET voltage circuit42includes a second voltage amplifier50(denoted as “AMP-L”) and a second offset capacitor52. The first voltage amplifier46is configured to generate a first initial ET voltage VAMP-Hbased on an ET target voltage VTARGETand a feedback voltage VCCFB. The first offset capacitor48is coupled between the first voltage amplifier46and the output port38. The first offset capacitor48is configured to raise the first initial ET voltage VAMP-Hby a first offset voltage VOFF-Hto generate the first ET voltage VCC-H(VCC-H=VAMP-H+VOFF-H) at the output port38. In a non-limiting example, the feedback voltage VCCFBis proportional to the first ET voltage VCC-Hwhen the first ET voltage circuit40is activated to generate the first ET voltage VCC-Hat the output port38.

The second voltage amplifier50is configured to generate a second initial ET voltage VAMP-Lbased on the ET target voltage VTARGETand the feedback voltage VCCFB. The second offset capacitor52is coupled between the second voltage amplifier50and the output port38. The second offset capacitor52is configured to raise the second initial ET voltage VAMP-Lby a second offset voltage VOFF-Lto generate the second ET voltage VCC-L(VCC-L=VAMP-L+VOFF-L) at the output port38. In a non-limiting example, the feedback voltage VCCFBis proportional to the second ET voltage VCC-Lwhen the second ET voltage circuit42is activated to generate the second ET voltage VCC-Lat the output port38.

The first offset capacitor48is chosen to have a first capacitance and the second offset capacitor52is chosen to have a second capacitance substantially smaller than the first capacitance. Notably, the second capacitance is said to be substantially smaller than the first capacitance when the second capacitance is less than one-thirtieth ( 1/30) of the first capacitance. In a non-limiting example, the first capacitance can be approximately 2.2 microFarad (g) and the second capacitance can be approximately 31 nanoFarad (nF). It should be appreciated that the first capacitance and the second capacitance can also be any other suitable values.

Each of the first voltage amplifier46and the second voltage amplifier50is configured to operate based on a first supply voltage VSUP-Hor a second supply voltage VSUP-Lwhich is lower than the first supply voltage VSUP-H. In a non-limiting example, the multi-bandwidth ETIC32includes a supply voltage circuit54configured to generate the first supply voltage VSUP-Hand the second supply voltage VSUP-L.

The tracker circuit44may include a multi-level charge pump (MCP)56configured to generate a low-frequency voltage VDCbased on a battery voltage

VBAT. The tracker circuit44also includes a power inductor58coupled between the MCP56and the output port38. The power inductor58is configured to induce a low-frequency current IDC(e.g., a direct current) at the output port38based on the low-frequency voltage VDC.

The multi-bandwidth ETIC32includes a control circuit60, which can be provided as a microprocessor, a microcontroller, or a field-programmable gate array (FPGA), as an example. The control circuit60may be coupled to the first ET voltage circuit40, the second ET voltage circuit42, the tracker circuit44, and/or the supply voltage circuit54. As discussed in detail below, the control circuit60can be configured to control the first ET voltage circuit40, the second ET voltage circuit42, and the tracker circuit44to output the first ET voltage VCC-H, the second ET voltage VCC-L, the modulated APT voltage VAPT-M, or the APT voltage VAPTat the output port38based on the modulation bandwidth of the RF signal36.

The control circuit60may receive a bandwidth indication signal62(e.g., from a transceiver circuit) that is indicative of the modulation bandwidth of the RF signal36. In one example, the control circuit60activates the first ET voltage circuit40and deactivates the second ET voltage circuit42to provide the first ET voltage VCC-Hto the amplifier circuit34as the modulated voltage VCCwhen the RF signal36is modulated in the first modulation bandwidth. In another example, the control circuit60deactivates the first ET voltage circuit40and activates the second ET voltage circuit42to provide the second ET voltage VCC-Lto the amplifier circuit34as the modulated voltage VCCwhen the RF signal36is modulated in the second modulation bandwidth.

In another example, the control circuit60deactivates the first ET voltage circuit40and the second ET voltage circuit42and causes the tracker circuit44to generate the low-frequency voltage VDCas the modulated APT voltage VAPT-Mwhen the RF signal36is modulated in the third modulation bandwidth. Accordingly, the amplifier circuit34receives the modulated APT voltage VAPT-Mas the modulated voltage VCC.

In another example, the control circuit60deactivates the first ET voltage circuit40and the second ET voltage circuit42and causes the tracker circuit44to generate the low-frequency voltage VDCas the APT voltage VAPTwhen the amplifier circuit34is only configured to amplify the RF signal36based on the APT voltage VAPT. Accordingly, the amplifier circuit34receives the APT voltage VAPTas the modulated voltage VCC. Furthermore, the control circuit60is further configured to cause the tracker circuit44to provide the low-frequency current IDCto the amplifier circuit34via the output port38.

In addition to generating the first ET voltage VCC-H, the first voltage amplifier46may be configured to source a first high-frequency current IAC-H(e.g., an alternating current) at the output port38. Similarly, the second voltage amplifier50may be configured to source a second high-frequency current IAC-L(e.g., an alternating current) at the output port38. In this regard, the first voltage amplifier46may be configured to generate a first sense current ISENSE-Hto indicate an amount of the first high-frequency current IAC-Hbeing sourced by the first voltage amplifier46. Likewise, the second voltage amplifier50may be configured to generate a second sense current ISENSE-Lto indicate an amount of the second high-frequency current IAC-Lbeing sourced by the second voltage amplifier50.

The multi-bandwidth ETIC32may include a first multiplexer64and a second multiplexer66. The first multiplexer64may be configured based on a selection signal68to selectively provide one of the first initial ET voltage VAMP-Hand the second initial ET voltage VAMP-Lto the control circuit60. The second multiplexer66may be configured based on the selection signal68to selectively provide one of the first sense current ISENSE-Hand the second sense current ISENSE-Lto the control circuit60. In a non-limiting example, the selection signal68can be provided by the transceiver circuit, the control circuit60, or any other control circuit. More specifically, when the first voltage amplifier46is activated and the second voltage amplifier50is deactivated, the selection signal68causes the first multiplexer64and the second multiplexer66to provide the first initial ET voltage VAMP-Hand the first sense current ISENSE-Hto the control circuit60. In contrast, when the first voltage amplifier46is deactivated and the second voltage amplifier50is activated, the selection signal68causes the first multiplexer64and the second multiplexer66to provide the second initial ET voltage VAMP-Land the second sense current ISENSE-Lto the control circuit60.

The multi-bandwidth ETIC32may include a target voltage circuit70configured to generate the ET target voltage VTARGETfor the first voltage amplifier46and the second voltage amplifier50. The multi-bandwidth ETIC32may also include a digital-to-analog converter (DAC)72configured to generate a reference target offset voltage VOFFSET-TGT-REF, which may be a constant voltage. The multi-bandwidth ETIC32may include a voltage scaler74and a voltage combiner76. The voltage scaler74may be configured to scale the ET target voltage VTARGETbased on a predefined scaling factor K (0≤K≤1) to generate a scaled ET target voltage VTGT-SCALE. The voltage combiner76is configured to combine the reference target offset voltage VOFFSET-TGT-REFwith the scaled ET target voltage VTGT-SCALEto generate a modulated target offset voltage VOFFSET-TGT-MOD.

In one non-limiting example, when the control circuit60determines that the RF signal36corresponds to the first modulation bandwidth (e.g., >180 KHz or 1 RB), the control circuit60activates the first voltage amplifier46and deactivates the second voltage amplifier50and sets the scaling factor K to zero (0). As a result, the modulated target offset voltage VOFFSET-TGT-MODequals the reference target offset voltage VOFFSET-TGT-REF. Concurrently or subsequently, the first multiplexer64and the second multiplexer66may be controlled via the selection signal68to provide the first initial ET voltage VAMP-Hand the first sense current ISENSE-Hto the control circuit60. The control circuit60may also control the supply voltage circuit54to provide the first supply voltage VSUP-Hto the first voltage amplifier46. The modulated target offset voltage VOFFSET-TGT-MODand the first supply voltage VSUP-Hmay be expressed in equations (Eq. 1 and Eq. 2) below.
VOFFSET-TGT-MOD=VOFFSET-TGT-REF=VCC-MIN−Nheadroom(Eq. 1)
VSUP-H=(VCC-MAX−VCC-MIN)+Nheadroom+Pheadroom(Eq. 2)

In another non-limiting example, when the control circuit60determines that the RF signal36corresponds to the second modulation bandwidth (e.g., ≈180 KHz or 1 RB), the control circuit60deactivates the first voltage amplifier46and activates the second voltage amplifier50and sets the scaling factor K to be between zero (0) and one (1) (0<K<1). Concurrently or subsequently, the first multiplexer64and the second multiplexer66may be controlled via the selection signal68to provide the second initial ET voltage VAMP-Land the second sense current ISENSE-Lto the control circuit60. The control circuit60may also control the supply voltage circuit54to provide the second supply voltage VSUP-Lto the second voltage amplifier50. The modulated target offset voltage VOFFSET-TGT-MODand the second supply voltage VSUP-Lmay be expressed in equations (Eq. 3 and Eq. 4) below.
VOFFSET-TGT-MOD=VCC-MIN−Nheadroom+K*(VCC−VCC-MIN)   (Eq. 3)
VSUP-L=(1−K)*(VCC-MAX−VCC-MIN)+Nheadroom+Pheadroom(Eq. 4)

By comparing Eq. 2 and Eq. 4, it can be seen that the second supply voltage VSUP-Lis lower than the first supply voltage VSUP-Hdue to the scaling factor K. As an example, if K=0.5 then the second supply voltage VSUP-Lis almost one-half (½) of the first supply voltage VSUP-H. Accordingly, the second voltage amplifier50may generate the second initial ET voltage VAMP-Lat almost ½ of the first initial ET voltage VAMP-H, and the second offset capacitor52may be modulated to provide the second offset voltage VOFF-Lthat is almost ½ of the first offset voltage VOFF-H. As such, the second capacitance of the second offset capacitor52can be configured to be substantially less than the first capacitance of the first offset capacitor48. As a result, the second voltage amplifier50may operate with an improved efficiency when the RF signal36is modulated in the second modulation bandwidth.

In another non-limiting example, when the control circuit60determines that the RF signal36corresponds to the third modulation bandwidth (e.g., 90 KHz or ½ RB), the control circuit60deactivates the first voltage amplifier46and the second voltage amplifier50and sets the scaling factor K to one (1). As a result, the modulated target offset voltage VOFFSET-TGT-MODequals a sum of the reference target offset voltage VOFFSET-TGT-REFand the ET target voltage VTARGET(VOFFSET-TGT-MOD=VOFFSET-TGT-REF+VTARGET). The first multiplexer64, the second multiplexer66, and the supply voltage circuit54are also disabled. Accordingly, the tracker circuit44can be configured to generate the low-frequency voltage VDCbased on the modulated target offset voltage VOFFSET-TGT-MOD. As a result, the MCP56generates the low-frequency voltage VDCas the modulated APT voltage VAPT-M.

The bandwidth of the modulated APT voltage VAPT-Mmay depend on the power inductor58as well as the first offset capacitor48or the second offset capacitor52, as shown in the equation (Eq. 5) below.
VAPT-MBandwidth=½π√{square root over (LC)}  (Eq. 5)

In Eq. 5 above, L represents an inductance of the power inductor58. C represents either the first capacitance of the first offset capacitor48or the second capacitance of the second offset capacitor52. In one example, the control circuit60may disable (e.g., bypass) the second offset capacitor52. Accordingly, the bandwidth of the modulated APT voltage VAPT-Mwill depend on the inductance of the power inductor58and the first capacitance of the first offset capacitor48. For example, if the inductance of the power inductor58equals 2 nanoHenry (nH) and the first capacitance of the first offset capacitor48equals 2 μF, then the bandwidth of the modulated APT voltage VAPT-Mwould be approximately 79.6 KHz according to Eq. 5.

In another example, the control circuit60may disable (e.g., bypass) the first offset capacitor48. Accordingly, the bandwidth of the modulated APT voltage VAPT-Mwill depend on the second capacitance of the second offset capacitor52. As discussed above, the second capacitance of the second offset capacitor52may be substantially smaller than the first capacitance of the first offset capacitor48. As such, the bandwidth of the modulated APT voltage VAPT-Mcan be higher when the control circuit60deactivates the first offset capacitor48.

In another non-limiting example, the control circuit60may determine (e.g., based on the bandwidth indication signal62) that it may be desirable for the amplifier circuit34to amplify the RF signal36based on the APT voltage VAPT. In this regard, the control circuit60deactivates the first voltage amplifier46and the second voltage amplifier50and sets the scaling factor K to zero (0). As a result, the modulated target offset voltage VOFFSET-TGT-MODequals the reference target offset voltage VOFFSET-TGT-REF. The first multiplexer64, the second multiplexer66, and the supply voltage circuit54are also disabled. Accordingly, the tracker circuit44can be configured to generate the low-frequency voltage VDCbased on the reference target offset voltage VOFFSET-TGT-REF(e.g., a constant voltage). As such, the MCP56generates the low-frequency voltage VDCas the APT voltage VAPT, which is also a constant voltage.

Alternative to employing the first voltage amplifier46and the second voltage amplifier50in the first ET voltage circuit40and the second ET voltage circuit42, respectively, it may be possible to share a single voltage amplifier between the first ET voltage circuit40and the second ET voltage circuit42. In this regard,FIG. 3is a schematic diagram of an exemplary ET apparatus78configured according to another embodiment of the present disclosure. Common elements betweenFIGS. 2 and 3are shown therein with common element numbers and will not be re-described herein.

The ET apparatus78includes a multi-bandwidth ETIC80. The multi-bandwidth ETIC80includes a first ET voltage circuit82and a second ET voltage circuit84configured to share a voltage amplifier86. The multi-bandwidth ETIC80may include a switch Svconfigured to alternately couple the voltage amplifier86to the first offset capacitor48or the second offset capacitor52.

In one non-limiting example, when the control circuit60determines that the RF signal36corresponds to the first modulation bandwidth (e.g., >180 KHz or 1 RB), the control circuit60activates the first ET voltage circuit82by coupling the voltage amplifier86to the first offset capacitor48. The control circuit60may also control the supply voltage circuit54to provide the first supply voltage VSUP-H, as shown in Eq. 2, to the voltage amplifier86. Accordingly, the voltage amplifier86generates an initial ET voltage VAMPbased on the ET target voltage VTARGETand the first supply voltage VSUP-H. The first offset capacitor48raises the initial ET voltage VAMPby the first offset voltage VOFF-Hto generate the first ET voltage VCC-Hat the output port38. Similar to the first voltage amplifier46inFIG. 2, the voltage amplifier86may be configured to source the first high-frequency current IAC-Hand generate a sense current ISENSEproportional to the first high-frequency current IAC-H.

In another non-limiting example, when the control circuit60determines that the RF signal36corresponds to the second modulation bandwidth (e.g., 180 KHz or 1 RB), the control circuit60activates the second ET voltage circuit84by coupling the voltage amplifier86to the second offset capacitor52. The control circuit60may also control the supply voltage circuit54to provide the second supply voltage VSUP-L, as shown in Eq. 4, to the voltage amplifier86. Accordingly, the voltage amplifier86generates the initial ET voltage VAMPbased on the ET target voltage VTARGETand the second supply voltage VSUP-L. The second offset capacitor52raises the initial ET voltage VAMPby the second offset voltage VOFF-Lto generate the second ET voltage VCC-Lat the output port38. Similar to the second voltage amplifier50inFIG. 2, the voltage amplifier86may be configured to source the second high-frequency current IAC-Land generate the sense current ISENSEproportional to the second high-frequency current IAC-L.

Given that the first ET voltage circuit82and the second ET voltage circuit84share the voltage amplifier86, it may be possible to eliminate the first multiplexer64and the second multiplexer66from the multi-bandwidth ETIC80. As a result, the control circuit60can be configured to receive the initial ET voltage VAMP, the sense current ISENSE, and the feedback voltage VCCFB.