Circuit module having dual-mode wideband power amplifier architecture

This application claims priority of U.S. provisional application Ser. No. 62/544,109 filed on Aug. 11, 2017, which is entirely incorporated herein by reference.

The invention relates to power amplifier architecture, and more particular to a circuit module having such power amplifier architecture.

Generally speaking, a conventional scheme is to adopt a power amplifier with a dynamically adjusted power supply to improve the efficiency of the power amplifier. However, as the operating signal bandwidth increases, the efficiency of a supply modulator, used for providing a supply power for the power amplifier, inevitably drops, and thus the overall system efficiency is degraded.

Further, another conventional scheme may adopt a power amplifier with a fixed power supply to improve the system linearity. However, to improve the system linearity, the fixed power supply may be increased, and thus this will sacrifice the system efficiency.

Therefore one of the objectives of the invention is to provide a circuit module having dual-mode wideband power amplifier architecture, to solve the above-mentioned problems.

According to embodiments of the invention, a circuit module is disclosed. The circuit module includes a power amplifier, a switch, and a bypass capacitor. The power amplifier has a signal input node coupled to an input signal, a signal output node to generate an output signal, and a power input node coupled to a supply output signal of a supply modulator. The switch is coupled between the power input node of the power amplifier and the bypass capacitor. The bypass capacitor is an equivalently removable bypass capacitor coupled between the switch and a ground level.

According to embodiments of the invention, a method of operating a power amplifier circuit module is disclosed. The power amplifier circuit module includes a power amplifier having a power input node for receiving a supply signal from a supply modulator. The method includes electrically connecting a bypass capacitor to the power input node when the power amplifier circuit module operates at a first mode, and electrically disconnecting the bypass capacitor from the power input node when the power amplifier circuit module operates at a second mode different from the first mode. The distance from the bypass capacitor to the power amplifier is shorter than the distance from the bypass capacitor to the supply modulator.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

FIG. 1 is a block diagram of a circuit module according to a first embodiment of the invention.

FIG. 2 shows a modification embodiment of circuit module as shown on FIG. 1 .

FIG. 3 shows another modification embodiment of circuit module as shown on FIG. 1 .

FIG. 4 is a diagram of a circuit module according to a second embodiment of the invention.

FIG. 5 is a diagram showing a modification of the circuit module based on the embodiment of FIG. 4 .

FIG. 6 is a diagram showing a modification of a circuit module according to the embodiment of FIG. 4 .

FIG. 7 is a diagram showing another modification of a circuit module according to the embodiment of FIG. 4 .

The invention aims at providing a solution of dual-mode (hybrid) wideband power amplifier circuit structure/architecture for a wideband supply modulator which can operate at small/large signal bandwidths, to improve the efficiency of the whole system as well as the system linearity. In some examples of the invention, two modes of operation are supported, namely a dynamic supply mode (for example, an envelope tracking scheme) and a fixed supply mode (for example, an average power tracking scheme). The selection of the mode to be used in providing the power supply to the PA is performed by a mode selection signal generated from a mode control module. In dynamic supply mode, the PA power supply is a time varying signal, which tracks the required signal envelope, in order to achieve the efficiency benefits. In fixed supply mode, the PA power supply is fixed at a specific voltage requirement in order to support the transmitted waveform, in order to achieve the linearity benefits. In some examples of the invention, the mode selection is based on signal bandwidth. For small bandwidth, the mode control module selects dynamic supply mode and the power amplifier circuit operates with dynamic power supply. For large bandwidth, the mode control module selects fixed supply mode and the power amplifier circuit operates with fixed power supply. This solution employs and places removable bypass capacitor(s) in the neighborhood of power amplifier(s). The bypass capacitor(s) in the neighborhood of a power amplifier can be removed (e.g. electrically disconnected from the power amplifier) when the power amplifier is supplied with a dynamically adjusted power supply (e.g. a supply modulator operates at the small signal bandwidth). This improves the system efficiency and is suitable for the small bandwidth supply modulation. By removing the bypass capacitor(s), the capacitance of the bypass capacitor(s) would not affect the loading of the power amplifier circuit. Additionally, the bypass capacitor(s) in the neighborhood of the power amplifier can exist (e.g. electrically connected to the power amplifier) and can be seen by the power amplifier when the power amplifier is supplied with a fixed power supply (e.g. the supply modulator operates at the large signal bandwidth). The removable bypass capacitor(s) in this mode can be used to increase the purity of the voltage of the fixed power supply, to keep the voltage of the fixed power supply constant, and/or to filter the noise, thereby improving the system linearity as well as the system efficiency. This is because if the bypass capacitor(s) is not electrically connected, the voltage of the fixed power supply needs to be increased in order to improve the linearity, and increasing the voltage of the fixed power supply results inefficiency sacrifice. By providing bypass capacitor(s) under fixed supply mode or large bandwidth condition and removing the bypass capacitor(s) under dynamic supply mode or small bandwidth condition, the efficiency and linearity of the whole system are improved. In some examples, the bypass capacitor(s) are preferred to be placed or disposed closer to the power amplifier than to the supply modulator for ripple suppression and/or interference suppression.

FIG. 1 is a block diagram of a circuit module 100 according to a first embodiment of the invention. The circuit module 100 comprises a power amplifier PA 1 , a switch SW 1 , and at least one bypass capacitor Cb. The circuit module 100 for example is a radio frequency front end circuit module.

The power amplifier PA 1 has a signal input node coupled to an input signal SIN, a signal output node to generate an output signal SOUT, and a power input node coupled to a supply output signal VSP of a supply modulator 105 . The supply modulator 105 is configured to convert a system power into the supply output signal VSP for the power amplifier PA 1 . The supply modulator 105 may include a DC-DC converter, an envelope tracking modulator, or a pulse width modulator.

The switch SW 1 is coupled between the power input node of the power amplifier PA 1 and the bypass capacitor Cb which is coupled between the switch SW 1 and a ground level. The switch SW 1 for example may be implemented by using a MOS transistor (but not limited).

The circuit module 100 is a dual-mode wideband circuit module in which the power amplifier PA 1 can be regarded as a dual-mode wideband power amplifier. The circuit module 100 has two modes and operates under different modes for different small/larger signal bandwidths, i.e. a hybrid circuit module. For example, the circuit module 100 operates under a first mode when the supply modulator 105 operates at a first signal bandwidth such as a small signal bandwidth. In the first mode, the switch SW 1 is turned off to become open when the supply modulator 105 operates at the small signal bandwidth, and the power input node of power amplifier PA 1 is electrically disconnected from the bypass capacitor Cb. The bypass capacitor Cb is not seen by the power amplifier PA 1 ; equivalently, the bypass capacitor Cb in this mode is removed. The supply modulator 105 is arranged to track the envelope of the signal outputted by or inputted to the power amplifier to modulate and provide the supply output signal VSP for the power amplifier PA 1 , and the power amplifier PA 1 is used as an envelope tracking amplifier. This can be achieved by providing the supply modulator 105 with the information of envelope of the transmitted signal in either digital form or analog form. Moreover, since the switch SW 1 is turned off, the capacitor loading can be reduced.

The circuit module 100 operates under a second mode when the supply modulator 105 operates at a second signal bandwidth such as a large signal bandwidth larger than the first signal bandwidth. In the second mode, the switch SW 1 is turned on to become closed when the supply modulator 105 operates at the larger signal bandwidth, and the power input node of power amplifier PA 1 is electrically connected to the bypass capacitor Cb. The bypass capacitor Cb is seen by the power amplifier PA 1 in this mode. The power supply signal VSP is fixed at the minimum voltage requirement of the power amplifier (e.g. fixed at a level corresponding to the maximum of the transmitted envelope waveform plus a margin) in order to support the transmitted waveform, for example for a time period between power level updates. The power amplifier PA 1 is used as an average power tracking amplifier. Since the switch SW 1 is turned on and the bypass capacitor Cb is seen, the supply output signal VSP for the power amplifier PA 1 can be regulated. In addition, the switch SW 1 is controlled by a mode selection signal generated from a mode control module (not shown in FIG. 1 ). In some examples, the mode control module is included in a baseband processing module or controlled by the baseband processing module.

In addition, in this embodiment, the circuit module 100 is implemented within an integrated circuit chip. That is, the power amplifier PA 1 , switch SW 1 , and bypass capacitor Cb are encapsulated or packaged within the integrated circuit chip. As shown on FIG. 1 , the dotted line indicates the chip boundary of such integrated circuit chip.

In addition, when the switch SW 1 is turned on to be closed, the circuit distance from the bypass capacitor Cb to the power amplifier PA 1 is shorter than the circuit distance from the bypass capacitor Cb to the supply modulator 105 . That is, the bypass capacitor Cb is closer to the power amplifier PA 1 than the supply modulator 105 . In this way, the performance of ripple suppression or interference (e.g. adjacent channel leakage ratio) suppression can be further improved.

Further, in other implementation, the power amplifier PA 1 and switch SW 1 may be implemented within the integrated circuit chip, and the bypass capacitor Cb may be configured to be externally connected to the integrated circuit chip. That is, the capacitor Cb is not encapsulated within such integrated circuit chip. FIG. 2 shows a modification embodiment of circuit module 100 as shown on FIG. 1 . As shown on FIG. 2 , the dotted line indicates the chip boundary of such integrated circuit chip, and the bypass capacitor Cb is not included within the chip boundary. It is noted that in this embodiment the bypass capacitor Cb is closer to the power amplifier PA 1 than the supply modulator 105 when the switch SW 1 is turned on. Similarly, the performance of ripple suppression or interference (e.g. adjacent channel leakage ratio) suppression can be further improved.

Further, in other implementation, the power amplifier PA 1 is implemented within the integrated circuit chip, and the switch SW 1 and bypass capacitor Cb can be configured to be externally connected to the integrated circuit chip. That is, the bypass capacitor Cb and switch SW 1 are not encapsulated within such integrated circuit chip. FIG. 3 shows another modification embodiment of circuit module 100 as shown on FIG. 1 . As shown on FIG. 3 , the dotted line indicates the chip boundary of such integrated circuit chip, and the switch SW 1 and bypass capacitor Cb are not included within the chip boundary. The bypass capacitor Cb is closer to the power amplifier PA 1 than the supply modulator 105 when the switch SW 1 is turned on. Similarly, the performance of ripple suppression or interference (e.g. adjacent channel leakage ratio) suppression can be further improved.

In other embodiments, the circuit module may be formed by multiple-stage power amplifiers. FIG. 4 is a diagram of a circuit module 400 according to a second embodiment of the invention. As shown on FIG. 4 , the circuit module 400 comprises multiple-stage power amplifiers connected in series at plurality of stages. For example, the circuit module 400 comprises the power amplifier PA 1 at the output stage and at least one power amplifier PA 2 at the input stage. The power amplifiers PA 1 and PA 2 are encapsulated within an integrated circuit chip, and the dotted line on FIG. 4 indicates the chip boundary of such integrated circuit chip.

The signal input node of power amplifier PA 2 is coupled to the input signal SIN, and its output node is coupled to the signal input node of power amplifier PA 1 . The power input node of power amplifier PA 2 is coupled to the supply output signal VSP of supply modulator 105 via a port P 2 of the integrated circuit chip. An internal capacitor C 1 is encapsulated within the integrated circuit chip and is placed and coupled between the power input node of power amplifier PA 2 and the ground level. An external capacitor C 2 is externally coupled to the port P 2 of such integrated circuit chip and is placed and coupled between the port P 2 and the ground level. For example, the internal capacitor C 1 and external capacitor C 2 may be configured to be closer to the power input node of power amplifier PA 2 and port P 2 , respectively.

The signal input node of power amplifier PA 1 is coupled to the output node of power amplifier PA 2 , and the power amplifier PA 1 generates the output signal SOUT at its signal output node. The power input node of power amplifier PA 1 is coupled to the supply output signal VSP of supply modulator 105 via a port P 1 of the integrated circuit chip. An internal capacitor C 1 is encapsulated within the integrated circuit chip and is placed and coupled between the power input node of power amplifier PA 1 and the ground level. An external capacitor C 2 is externally coupled to the port P 1 of such integrated circuit chip and is placed and coupled between the port P 1 and the ground level. For example, the internal capacitor C 1 and external capacitor C 2 may be configured to be closer to the power input node of power amplifier PA 1 and port P 1 , respectively. The internal capacitors C 1 are used as voltage stabilizer elements for circuit element(s) within the integrated circuit chip, and the external capacitors C 2 are used as voltage stabilizer elements for circuit element(s) externally connected to the integrated circuit chip; the capacitors C 1 and C 2 may be optional.

The supply modulator 105 is configured to convert a system power into the supply output signal VSP for the power amplifiers PA 1 and PA 2 . The supply modulator 105 may include a DC-DC converter, an envelope tracking modulator, or a pulse width modulator.

The bypass capacitor Cb is coupled to the power input node of power amplifier PA 1 via the switch SW 1 and a port Pb of the integrated circuit chip. The bypass capacitor Cb is closer to the port Pb.

Similarly, the circuit module 400 is a dual-mode wideband circuit module in which the power amplifiers PA 1 and PA 2 can be regarded as dual-mode wideband power amplifiers. The circuit module 400 has two modes and operates under different modes for different signal bandwidths, i.e. a hybrid circuit module. For example, the circuit module 400 operates under a first mode when the supply modulator 105 operates at a first signal bandwidth such as a small signal bandwidth. In the first mode, the switch SW 1 is turned off to become open when the supply modulator 105 operates at the small signal bandwidth, and the power input node of power amplifier PA 1 is electrically disconnected from the bypass capacitor Cb. Also, the power input node of power amplifier PA 2 at the input stage is electrically disconnected from the bypass capacitor Cb. In this situation, the bypass capacitor Cb is not seen by the power amplifiers PA 1 and PA 2 . Equivalently, for power amplifiers PA 1 and PA 2 , the bypass capacitor Cb is removed. The supply modulator 105 is arranged to track the envelope of the signal outputted by or inputted to the power amplifiers to modulate and provide the supply output signal VSP for the power amplifiers PA 1 and PA 2 , and the power amplifiers PA 1 and PA 2 are used as envelope tracking amplifiers. This can be achieved by providing the supply modulator 105 with the information of envelope of the transmitted signal in either digital form or analog form. Moreover, since the switch SW 1 is turned off, the capacitor loading can be reduced.

Additionally, the circuit module 400 operates under a second mode when the supply modulator 105 operates at a second signal bandwidth such as a large signal bandwidth larger than the first signal bandwidth. In the second mode, the switch SW 1 is turned on to become closed when the supply modulator 105 operates at the larger signal bandwidth, and the power input node of power amplifier PA 1 is electrically connected to the bypass capacitor Cb. Also, the power input node of power amplifier PA 2 is electrically connected to the bypass capacitor Cb. The bypass capacitor Cb is seen by the power amplifiers PA 1 and PA 2 . The circuit distance from the power input node of power amplifier PA 2 to the bypass capacitor Cb may be longer than that from the power input node of power amplifier PA 1 to the bypass capacitor Cb. The bypass capacitor Cb is still closer to the power amplifiers PA 1 and PA 2 than the supply modulator 105 . The power supply signal VSP is fixed at the minimum voltage requirement of the power amplifiers (e.g. fixed at a level corresponding to the maximum of the transmitted envelope waveform plus a margin) in order to support the transmitted waveform. The power amplifiers PA 1 and PA 2 are used as average power tracking amplifiers. Since the switch SW 1 is turned on and the bypass capacitor Cb is seen, the supply output signal VSP for the power amplifiers PA 1 and PA 2 can be regulated.

For example (but not limited), if the supply modulator 105 is configured to operate under a large signal bandwidth from zero to the maximum frequency, then the circuit module 400 operates under the second mode, and the switch SW 1 is turned on to become closed. The power amplifiers PA 1 and PA 2 are used as average power tracking amplifiers. Additionally, if the supply modulator 105 is configured to operate under a small signal bandwidth from zero to a threshold frequency lower than the maximum frequency, then the circuit module 400 operates under the first mode, and the switch SW 1 is turned off to become open. The power amplifiers PA 1 and PA 2 are used as envelope tracking amplifiers. In some examples, the threshold frequency corresponds to the bandwidth that the supply modulator 105 can operate. In some examples, the threshold frequency is around 60 MHz.

Further, for implementation, the capacitance of bypass capacitor Cb may be configured to be one thousand times more than the capacitances of capacitors C 1 and C 2 . For example, the capacitance of bypass capacitor Cb may be configured as a value of the order of μF, and the capacitances of capacitors C 1 and C 2 are configured as the values of the order of pF. For instance, the capacitances of capacitors C 1 and C 2 may be designed as 10-100 pF (but not limited).

FIG. 5 is a diagram showing a modification 500 of the circuit module based on the embodiment of FIG. 4 . As shown by FIG. 5 , the power input node of power amplifier PA 2 is coupled to another distinct bypass capacitor Cb′ via the switch SW 2 and the port Pb′ of integrated circuit chip. Identically, the power input node of power amplifier PA 2 is coupled to the supply output signal VSP of supply modulator 105 via the port P 2 of the integrated circuit chip. Identically, the circuit module 500 is a dual-mode wideband circuit module in which the power amplifiers PA 1 and PA 2 can be regarded as dual-mode wideband power amplifiers. The circuit module 500 has two modes and operates under different modes for different signal bandwidths, i.e. a hybrid circuit module. For example, the circuit module 500 operates under a first mode when the supply modulator 105 operates at a first signal bandwidth such as a small signal bandwidth. In the first mode, the switches SW 1 and SW 2 are turned off to become open respectively when the supply modulator 105 operates at the small signal bandwidth, and the power input nodes of power amplifiers PA 1 and PA 2 are electrically disconnected from the bypass capacitors Cb and Cb′, respectively. The bypass capacitors Cb and Cb′ are not seen by the power amplifiers PA 1 and PA 2 . For power amplifiers PA 1 and PA 2 , the bypass capacitors Cb and Cb′ are removed in this situation. The supply modulator 105 is arranged to track the envelope of the signal provided by or inputted to the power amplifiers to modulate and provide the supply output signal VSP for the power amplifiers PA 1 and PA 2 , and the power amplifiers PA 1 and PA 2 are used as envelope tracking amplifiers. This can be achieved by providing the supply modulator 105 with the information of envelope of the transmitted signal in either digital form or analog form. Moreover, since the switches SW 1 and SW 2 are turned off, the capacitor loading can be reduced.

Additionally, the circuit module 500 operates under a second mode when the supply modulator 105 operates at a second signal bandwidth such as a large signal bandwidth larger than the first signal bandwidth. In the second mode, the switches SW 1 and SW 2 are turned on to become closed respectively when the supply modulator 105 operates at the larger signal bandwidth, and the power input nodes of power amplifiers PA 1 and PA 2 are electrically connected to the bypass capacitors Cb and Cb′, respectively. The bypass capacitors Cb and Cb′ are seen by the power amplifiers PA 1 and PA 2 . The circuit distance from bypass capacitor Cb to power amplifier PA 1 is shorter than that from bypass capacitor Cb to supply modulator 105 , and also the circuit distance from bypass capacitor Cb′ to power amplifier PA 2 is shorter than that from bypass capacitor Cb′ to supply modulator 105 . That is, the bypass capacitors Cb and Cb′ are closer to the power amplifiers PA 1 and PA 2 than the supply modulator 105 . In this mode, the power supply signal VSP is fixed at the minimum voltage requirement of the power amplifier (e.g. fixed at a level corresponding to the maximum of the transmitted envelope waveform plus a margin) in order to support the transmitted waveform. The power amplifiers PA 1 and PA 2 are used as average power tracking amplifiers. Since the switches SW 1 and SW 2 are turned on and the bypass capacitors Cb and Cb′ are seen, the supply output signal VSP for the power amplifiers PA 1 and PA 2 can be regulated.

FIG. 6 is a diagram showing a modification 600 of a circuit module according to the embodiment of FIG. 4 . As shown on FIG. 6 , the circuit module 600 comprises multiple power amplifiers connected in series at plurality of stages. For example, the circuit module 600 comprises the power amplifier PA 1 at the output stage and the power amplifier PA 2 at the input stage. The power amplifiers PA 1 and PA 2 are encapsulated or packaged within an integrated circuit chip, and the dotted line on FIG. 6 indicates the chip boundary of such integrated circuit chip. The bypass capacitor Cb is coupled to the power input node of power amplifier PA 1 via the switch SW 1 and the port Pb of the integrated circuit chip. In addition, the power input node of power amplifier PA 2 is coupled to the power input node of power amplifier PA 1 and the supply output signal VSP via the node P 1 .

Identically, the circuit module 600 is a dual-mode wideband circuit module in which the power amplifiers PA 1 and PA 2 can be regarded as dual-mode wideband power amplifiers. The circuit module 600 has two modes and operates under different modes for different signal bandwidths, i.e. a hybrid circuit module. For example, the circuit module 600 operates under a first mode when the supply modulator 105 operates at a first signal bandwidth such as a small signal bandwidth. In the first mode, the switch SW 1 is turned off to become open when the supply modulator 105 operates at the small signal bandwidth, and the power input nodes of power amplifiers PA 1 and PA 2 are electrically disconnected from the bypass capacitor Cb, respectively. The bypass capacitor Cb is not seen by the power amplifiers PA 1 and PA 2 . The bypass capacitor Cb is equivalently removed. In this mode, the supply modulator 105 is arranged to track the envelope of the signal provided by or inputted to the power amplifiers to modulate and provide the supply output signal VSP for the power amplifiers PA 1 and PA 2 , and the power amplifiers PA 1 and PA 2 are used as envelope tracking amplifiers. This can be achieved by providing the supply modulator 105 with the information of envelope of the transmitted signal in either digital form or analog form. Moreover, since the switch SW 1 is turned off, the capacitor loading can be reduced.

Additionally, the circuit module 600 operates under a second mode when the supply modulator 105 operates at a second signal bandwidth such as a large signal bandwidth larger than the first signal bandwidth. In the second mode, the switch SW 1 is turned on to become closed when the supply modulator 105 operates at the larger signal bandwidth, and the power input nodes of power amplifiers PA 1 and PA 2 are electrically connected to the bypass capacitor Cb respectively. The bypass capacitor Cb is seen by the power amplifiers PA 1 and PA 2 . The bypass capacitor Cb is closer to the power amplifiers PA 1 and PA 2 than the supply modulator 105 . In this mode, the power supply signal VSP is fixed at the minimum voltage requirement of the power amplifiers (e.g. fixed at a level corresponding to the maximum of the transmitted envelope waveform plus a margin) in order to support the transmitted waveform. The power amplifiers PA 1 and PA 2 are used as average power tracking amplifiers. Since the switch SW 1 is turned on and the bypass capacitor Cb is seen, the supply output signal VSP for the power amplifiers PA 1 and PA 2 can be regulated. Other functions and operations are similar and not detailed for brevity.

In other embodiments, the power amplifier PA 2 at the input stage may be an average power tracking amplifier instead of a hybrid power amplifier so as to reduce the implementation complexity. FIG. 7 is a diagram showing another modification 700 of a circuit module according to the embodiment of FIG. 4 . As shown on FIG. 7 , the circuit module 700 comprises multiple power amplifiers connected in series at plurality of stages. For example, the circuit module 700 comprises the power amplifier PA 1 at the output stage and the power amplifier PA 2 at the input stage. The power amplifiers PA 1 and PA 2 are encapsulated or packaged within an integrated circuit chip, and the dotted line on FIG. 7 indicates the chip boundary of such integrated circuit chip. The bypass capacitor Cb is coupled to the power input node of power amplifier PA 1 via the switch SW 1 and the port Pb of the integrated circuit chip. The power input node of power amplifier PA 1 is coupled to a supply output signal VSP 1 of supply modulation 705 , and the power input node of power amplifier PA 2 is coupled to another supply output signal VSP 2 of supply modulator 705 via the port P 2 . The supply modulator 705 is arranged to provide the distinct supply output signals VSP 1 and VSP 2 which can be identical or different.

The circuit module 700 is a dual-mode wideband circuit module in which the power amplifier PA 1 is regarded as dual-mode wideband power amplifier and the power amplifier PA 2 is regarded as an average power tracking amplifier. The circuit module 700 has two modes and operates under different modes for different signal bandwidths, i.e. a hybrid circuit module. For example, the circuit module 700 operates under a first mode when the supply modulator 705 operates at a first signal bandwidth such as a small signal bandwidth. In the first mode, the switch SW 1 is turned off to become open when the supply modulator 705 operates at the small signal bandwidth, and the power input node of power amplifier PA 1 is electrically disconnected from the bypass capacitor Cb. The bypass capacitor Cb is not seen by the power amplifier PA 1 , and equivalently the bypass capacitor Cb is removed for the power amplifier PA 1 . The power input node of power amplifier PA 2 is electrically connected to the supply output signal VSP 2 via the port P 2 of the integrated circuit chip. In this mode, the supply modulator 705 is arranged to track the envelope of the signal provided by or inputted to the power amplifiers to modulate and provide the supply output signal VSP 1 for the power amplifier PA 1 , and the power amplifier PA 1 is used as an envelope tracking amplifier. The switch SW 1 is turned off, and the capacitor loading can be reduced. In addition, the supply modulator 705 is arranged to generate the supply output signal VSP 2 for the power amplifier PA 2 based on the minimum voltage requirement of the power amplifier (e.g. a level corresponding to the maximum of the transmitted envelope waveform plus a margin), and the power amplifier PA 2 is used as an average power tracking amplifier. The supply output signal VSP 1 in this mode is different from the supply output signal VSP 2 .

Additionally, the circuit module 700 operates under a second mode when the supply modulator 705 operates at a second signal bandwidth such as a large signal bandwidth larger than the first signal bandwidth. In the second mode, the switch SW 1 is turned on to become closed when the supply modulator 705 operates at the larger signal bandwidth, and the power input node of power amplifier PA 1 is electrically connected to the bypass capacitor Cb. The bypass capacitor Cb in this situation is seen by the power amplifier PA 1 . The bypass capacitor is closer to the power amplifier PA 1 than the supply modulator 705 . In this mode, the supply modulator 705 is arranged to generate the supply output signal VSP 1 for the power amplifier PA 1 based on the minimum voltage requirement of the power amplifier (e.g. a level corresponding to the maximum of the transmitted envelope waveform plus a margin) in order to support the transmitted waveform, and the power amplifier PA 1 is used as an average power tracking amplifier. The supply output signal VSP 1 in this mode may be different from or equal to the supply output signal VSP 2 . Since the switch SW 1 is turned on and the bypass capacitor Cb is seen, the supply output signal VSP 1 for the power amplifier PA 1 can be regulated. Other functions and operations are similar and not detailed for brevity.

Although the switch SW 1 is shown inside the chip boundary and the bypass capacitors Cb and Cb′ are shown outside the chip boundary in FIG. 4 - FIG. 7 , it is not meant to be a limitation. The power amplifier circuit modules 400 - 700 can be modified in similar ways shown in FIG. 1 - FIG. 3 . That is, the switch SW 1 can be encapsulated or packaged within the integrated circuit chip or externally coupled to the integrated circuit chip (e.g. not encapsulated within such integrated circuit chip). The bypass capacitors Cb and Cb′ can be encapsulated or packaged within the integrated circuit chip or externally coupled to the integrated circuit chip (e.g. not encapsulated within such integrated circuit chip). The circuit modules 400 - 700 may have two or more stages of power amplifiers.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.