KR20180065930A - A multi-stage amplifier in which a power supply voltage is adaptively supplied - Google Patents

Abstract

Disclosed is a multi-stage amplifier to which power supply voltage is adaptively supplied. The multi-stage amplifier to which the power supply voltage is adaptively supplied comprises: a plurality of power amplifiers sequentially amplifying and outputting an input signal through a plurality of steps; a detector detecting an output of the power amplifier belonging to the selected step among the plurality of steps; and a voltage controller adaptively supplying the voltage applied to the power amplifier belonging to one of the previous step of the final step of the plurality of steps according to the output detected by the detector. Therefore, linearity and power efficiency of the power amplifier can be improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a multi-stage amplifier that improves linearity and efficiency by applying an adaptive power supply voltage.

The present invention relates to a multi-stage amplifier to which a power supply voltage is adaptively applied, and more particularly, to a multi-stage amplifier in which a power supply voltage is adaptively applied to a power amplifier located at the previous stages of a final stage in a multi- To a multi-stage amplifier that improves linearity and efficiency by applying a Darlington circuit.

As the mobile communication technology continues to evolve, the demand for a power amplifier that increases the efficiency while satisfying the linearity standard required by the system continues to increase. Here, in order to solve the exponentially increasing use of mobile data, 5G mobile communication is expected to use frequencies above 20GHz. An important part of developing a power amplifier suitable for 5G mobile communications is that it must operate linearly up to the average output power of the power amplifier. Also, the power amplifier efficiency becomes important for low power operation.

In general, a multi-stage amplifier refers to an amplifier having a structure in which a plurality of amplifiers are connected in series to each other, and the output of the front-end amplifier is input to the rear-end amplifier.

In this case, the multi-stage amplifier may be configured in a two-stage or three-stage configuration depending on its use. As described above, it is possible to prevent the amplifier efficiency from being reduced due to power consumption and to satisfy the linearity .

However, the conventional multi-stage amplifier has a problem that the power efficiency is lowered and linearity is lowered by providing a fixed power supply voltage to the power supply voltage applied to each stage of the power amplifier.

In order to solve the above problems, an object of the present invention is to provide a multi-stage amplifier to which a power supply voltage is adaptively supplied.

According to an aspect of the present invention, there is provided a multi-stage amplifier to which a power supply voltage is adaptively supplied.

Here, a multi-stage amplifier to which a power supply voltage is adaptively supplied includes a plurality of power amplifiers for sequentially amplifying and outputting input signals through a plurality of stages, a plurality of power amplifiers And a voltage controller for adaptively supplying a voltage to be applied to the power amplifier belonging to one of the last stages of the plurality of stages according to the output detected by the detector.

Here, the detector can detect the output of the power amplifier belonging to the final stage.

Here, the detector can detect the output of the power amplifier belonging to the immediately preceding stage of the final stage.

Here, the voltage controller may adaptively supply the voltage applied to the power amplifier immediately before the final stage.

Here, the detector can detect the current flowing in the emitter of the transistor constituting the power amplifier belonging to the selected step.

Here, the detector can detect the voltage applied to the emitter of the transistor constituting the power amplifier belonging to the selected step.

Here, the detector may short-circuit the emitter of the transistor constituting the power amplifier belonging to the selected stage and detect the voltage applied to the base.

Wherein the voltage controller may adaptively change the voltage applied to the power amplifier belonging to one of the last stages of the plurality of stages to correspond to the waveform of the output signal detected by the detector.

The multi-stage amplifier may further include a plurality of bias circuits for setting operating points for at least one of the power amplifiers belonging to the plurality of stages.

Here, the bias circuit for setting the operating point of the power amplifier belonging to the first stage of the plurality of bias circuits may be a Darlington circuit connected with two transistors of the same polarity.

In the case of using the multi-stage amplifier adaptively supplied with the power supply voltage according to the present invention as described above, the power consumption can be minimized while satisfying the linearity of the power amplifier.

Particularly, the present invention can have a greater effect in an RF system used in mobile communication, and can be applied directly to a power amplifier implemented in an integrated circuit or a power amplifier manufactured in a hybrid configuration.

1 is a block diagram of a multi-stage amplifier including two stages.
2 is a graph comparing the ET (Envelope Tracking) technique for varying the supply voltage according to the output waveform envelope to the case of using a fixed supply voltage.
FIG. 3A is a graph illustrating the efficiency of the multi-stage power amplifier when the supply voltage VCC2 for the second stage power amplifier is fixed and the supply voltage VCC1 for the first stage power amplifier is changed in FIG.
FIG. 3B is an enlarged graph of the graph of FIG. 3A. FIG.
4 is an exemplary diagram for explaining the concept of ACLR (Adjacent Channel Leakage Power Ratio).
5 is a graph showing ACLR characteristics derived from the same environment as the circuit environment from which the results of FIG. 3 are derived.
6 is an exemplary block diagram of a multi-stage amplifier to which a power supply voltage is adaptively supplied.
FIG. 7 illustrates a circuit that may be configured in a first stage power amplifier of a multi-stage amplifier according to an embodiment of the present invention.
FIG. 8 is a circuit diagram in which a Darlington circuit is applied to the bias circuit in FIG. 7; FIG.
FIG. 9 is a graph of a simulation test result in which the circuits of FIG. 7 and FIG. 8 are compared with each other.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing.

The terms first, second, A, B, etc. may be used to describe various elements, but the elements should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a multi-stage amplifier including two stages.

1, an exemplary configuration of a multi-stage amplifier (multistage amplifier), the input matching circuit, the amplifier of the first stage has a (input matching circuit, input MC) (1 st Stage), the amplifier of the first stage (1 ^st Stage) output (2 ^nd Stage) having an input of the intermediate matching circuit (Inter MC) as an input, an intermediate matching circuit (Inter MC) connected between the input of the second stage (2 ^nd stage) ^And an output matching circuit (Output MC) connected to the output of the second stage amplifier (2nd stage). In this case, although a two-stage power amplifier is taken as an example in FIG. 1, it can be applied to a power amplifier having more stages according to a desired application field.

The first stage (1 ^st stage) is a driver amplifier (DA), which can deliver a RF signal (radio frequency signal) level suitable for a power amplifier (PA) with high gain have. In addition, the first stage power amplifier (1 ^st stage) can operate as a Class A amplifier in order to have a linear characteristic.

Where an A class amplifier may refer to an amplifier biased to operate across the transistor active region. Specifically, an A-class amplifier can exhibit an in-phase or inverted (180 °) phase difference with the input, and an operating point is set in the active region (or linear region) of the AC load line so that the input signal can be amplified and output without distortion have. Therefore, since the class A amplifier is sufficiently supplied with the current under a specific power supply voltage condition, the linearity of the amplifier can be well maintained.

The second stage amplifier (2 ^nd stage) is a power amplifier (PA) that can produce the high power required by the system.

The amplifier of the first stage (1 ^st stage) and the amplifier of the second stage (2 ^nd stage) can be operated by the applied power supply voltages (VCC1, VCC2) and reference voltages (Vref1, Vref2) .

Meanwhile, the power amplifier efficiency (Power Amplifier Efficiency) can be expressed by the following equation (1).

Referring to Equation (1), it can be seen that the efficiency of the power amplifier can be improved by reducing the applied power voltage (P _DC ). In this case, since the final stage of the multi-stage amplifier consumes the most power, the power supply voltage of the final stage is changed to a different power supply voltage according to the operation range of the power amplifier, or the power supply voltage of the final stage is changed in real- The efficiency of the amplifier can be improved.

Referring to FIG. 1, since the final stage is the second stage, the power supply voltage VCC2 of the amplifier at the second stage is changed according to the operation range (for example, one of 2V, 3V, 4V, It can be changed according to the output RF signal. At this time, it is possible to change the power supply voltage in real time by using a switch or a power supply voltage, or by using envelope tracking (ET) technology as a means or means for changing.

2 is a graph comparing the ET technique for varying the supply voltage according to the output waveform boundary Envelope to the case of using a fixed supply voltage.

A graph 2a shown on the left side of FIG. 2 shows a transmitted RF signal transmitted when a fixed voltage (Fixed PA Supply Voltage) is applied to the power amplifier. Here, the remaining portion except for the RF signal transmitted at the fixed supply voltage may be dissipated as heat.

A graph (2b) shown on the right side of FIG. 2 is a graph when the tracking amplifier changes the supply voltage (Tracking PA Supply Voltage) according to the waveform of an output signal (Transmitted RF Signal). Compared with the graph on the left, we can see that the dissipated as heat, which is the remainder (shown in red) except for the RF signal transmitted from the supply voltage, is much reduced.

Therefore, if the supply voltage supplied to the power amplifier at the final stage is changed according to the envelope of the output waveform, the efficiency of the power amplifier can be maximized.

On the other hand, unlike the final stage power amplifier, the amplifiers in the first stage (or the front stages of the final stage) which are operating in a sufficiently linear manner generally use a fixed supply voltage. This is because the power amplifier of the first stage (or the front stage of the final stage) uses an A class amplifier to ensure the linearity of the power amplifier located at the rear end of the first stage (or the front ends of the final stage). However, since the system becomes more complicated and is required to handle multifunction, the front end of the final stage, which is not the final stage, consumes about 1/2 of the current of the final stage, . In particular, the ratio of the quiescent current at the front end of the final stage to the quiescent current at the final stage may become larger.

Therefore, in order to improve the efficiency of the additional power amplifier, the present invention proposes a method of applying a power source voltage that is not fixed to the amplifier located at the ends of the final stage but is changed in some cases. For example, the power supply voltage VCC1 of the power amplifier at the first stage of FIG. 1 can be operated at a lower power supply voltage than a fixed power supply voltage, and the resulting graph will be described below.

FIG. 3A is a graph illustrating the efficiency of the multi-stage power amplifier when the supply voltage VCC2 for the second stage power amplifier is fixed and the supply voltage VCC1 for the first stage power amplifier is changed in FIG. FIG. 3B is an enlarged graph of the graph of FIG. 3A. FIG.

Referring to Figure 3a, the second stage of the amplifier (2 ^nd stage) for applying a power supply voltage (VCC2) fixed at 5V in and by changing the power supply voltage applied to the amplifier of the first stage (VCC1) efficiency of the power amplifier of Figure 1 (PAE). Specifically, when the power supply voltage (VCC2) applied to the amplifier of the second stage is fixed to 5 V and the power supply voltage (VCC1) applied to the amplifier of the first stage is changed to 2.5 V, 3.4 V and 5.0 V, ≪ / RTI > is the power amplifier efficiency (PAE). As can be seen from the graph, the power amplifier efficiency increases as the output power increases. And the power amplifier efficiency is about 40% at the maximum output power. At this time, when the power supply voltage VCC1 applied to the amplifier of the first stage is 2.5 V, it is confirmed that the efficiency is limited to 40% or less due to the limitation of the maximum power. At this time, since a general mobile communication terminal is not used at a maximum output point, efficiency at an average power is more important.

Thus, referring to FIG. 3B, the efficiency can be compared at an average output power of 25 dBm output. Specifically, the power amplifier efficiency (PAE) is 17.8%, 17.1% when the power supply voltage VCC1 applied to the amplifier of the first stage is 2.5V, 3.4V, 5V (DA2.5V, DA3.4V, DA5V) , And 14.9%, respectively.

4 is an exemplary diagram for explaining the concept of ACLR (Adjacent Channel Leakage Power Ratio).

To verify the linearity characteristics of the power amplifier, it is necessary to check the Adjacent Channel Leakage power Ratio (ACLR) value. The ACLR characteristic is obtained by applying an LTE (Long Term Evolution) signal to an RF input signal and then analyzing an RF signal output from the power amplifier through a signal analyzer to compare RF channel signals of a desired band with signals of adjacent bands .

Referring to FIG. 4, in the RF input spectrum for the input signal, there may be a Ref channel, an upper adjacent channel, and a lower adjacent channel. When the input signal passes through the power amplifier, adjacent channels (Upper adjacent channel) in the RF output spectrum may exist on both sides of the reference channel. Here, if the power in the bandwidth of the reference channel is P _ref and the power in the bandwidth of the adjacent channel is P _adj , the ACLR value can be derived as shown in Equation (2).

Here, since the adjacent channels are located above and below, there are also two powers within the bandwidth of the adjacent channel. Therefore, if ACLR_upper is derived from the ACLR derived by substituting the power in the bandwidth of the above adjacent channel into P _ref , and the power within the bandwidth of the adjacent channel below is substituted into P _ref , the resulting ACLR is denoted by ACLR_lower. May be the result of averaging ACLR_upper and ACLR_lower.

Hereinafter, the ACLR value in the two-stage multi-stage amplifier as shown in FIG. 1 is checked based on the ACLR calculation process.

5 is a graph showing ACLR characteristics derived from the same environment as the circuit environment from which the results of FIG. 3 are derived.

3, the ACLR value for the two-stage multi-stage amplifier as shown in FIG. 1 was confirmed. At this time, the VCC2 voltage was fixed to 5 V and the VCC1 voltage was measured while changing the voltage to 2.5 V, 3.4 V, and 5.0 V .

Referring to FIG. 5, when VCC1 is 5 V and the output power is 25 dBm or less, the ACLR value is -48 dBc or less. On the other hand, when VCC1 is 2.5 V and the output power is more than 24 dBm, the ACLR value increases sharply. In addition, although it is not shown in the drawing, it was confirmed that as VCC1 is lower than 2.5 V, ACLR values rapidly increase to -40 dBc, -30 dBc, and -20 dBc. When VCC1 is 3.4V, the ACLR value has a value between when VCC1 is 2.5V and when VCC1 is 5V.

5, when the output power of the power amplifier is 24 dBm, the power supply voltage VCC1 applied to the first stage power amplifier is 2.5 V, and the output power It is confirmed that applying 3.4V at 24dBm to 25dBm and 5.0V at 25dBm or more are effective in terms of power amplifier efficiency and linearity maintenance.

That is, if the power supply voltage applied to the power amplifier located at the front end of the power amplifier located at the final stage is changed based on the output power, the efficiency and linearity of the power amplifier can be improved.

6 is an exemplary block diagram of a multi-stage amplifier to which a power supply voltage is adaptively supplied.

Referring to FIG. 6, a multi-stage amplifier according to an embodiment of the present invention includes a plurality of power amplifiers 101 and 102 for sequentially amplifying and outputting input signals through a plurality of stages, A detector 111 for detecting an output of the power amplifier belonging to a selected stage of the plurality of stages, and a controller 111 for adjusting a voltage applied to the power amplifier belonging to one of the previous stages of the plurality of stages And a voltage controller 122 for supplying the voltage to the power source. At this time, in FIG. 6, two stages of amplifiers are shown, but the present invention is not limited thereto.

6, FIG. 1 shows a configuration in which a detector 111 and a voltage regulator (or a DC voltage regulator, 121 to 122) are additionally provided in the multi-stage power amplifiers 101 and 102 having two stages in FIG. . In addition, bias circuits (1 ^st Bias Circuit, 2 ^nd Bias Circuit, 131 - 132) are configured to set the respective operating points of the power amplifier 101 of the first stage and the power amplifier 102 of the second stage . 1, the multi-stage amplifier includes an input matching circuit 141 for transmitting an input signal to the first stage power amplifier, an intermediate matching circuit 142 for transmitting the output of the first stage power amplifier to the second stage power amplifier 142 And an output matching circuit 143 for receiving and outputting the output of the second stage power amplifier.

Here, the voltage controller 122 may be a voltage regulator (or a DC regulator) as shown in FIG. 6, but may be a DC / DC converter. The voltage controller 122 adjusts the voltage applied to the power amplifier belonging to the immediately preceding stage or the first stage 101 of the final stage (corresponding to the stage 102 because the stage is two stages in the drawing) according to the output detected by the detector 111, . In addition, the voltage controller 122 may adaptively change the voltage applied to the power amplifier belonging to one of the previous stages of the final stage, corresponding to the waveform of the output signal detected by the detector 111 (At this time, the ET technique described in FIG. 2 can be applied). Here, when the voltage controller 122 is a DC regulator, a power supply voltage can be selected and supplied using a switching circuit among various power supply voltages such as VDD1, VDD2,..., VDDN.

The detector 111 may detect the RF output power at the output matching circuit (Output MC, 143) located at the final output stage of the multi-stage amplifier. The power supply voltage applied to the power amplifier 101 in the first stage (or the front stages of the final stage) in the DC regulator can be changed by referring to the RF output power obtained from the detector 111. [ Here, the detector 111 may be configured in various forms. Thus, the linearity and efficiency of the multi-stage amplifier can be improved by changing the power supply voltage applied to the power amplifier located at the front ends of the final stage with reference to the RF output power.

It is to be noted that the detector 111 detects the RF output power at the final stage output circuit 143. However, if the detector 111 is connected to the output stage 143 at the final stage, There is a possibility that the output becomes lower. Therefore, the RF output power can be detected at a stage other than the final stage (for example, the front ends of the final stage), and when the RF output power is detected at a stage other than the final stage, You can set it differently. For example, the detector 111 can detect the output of the power amplifier belonging to the final stage. The detector 111 may also detect the output of the power amplifier belonging to the immediately preceding stage of the final stage.

Hereinafter, a method of detecting an output signal for the first stage power amplifier in a two-stage multi-stage amplifier as one of several examples of detecting output signals at the front ends of the final stage will be described.

FIG. 7 illustrates a circuit that may be configured in a first stage power amplifier of a multi-stage amplifier according to an embodiment of the present invention.

7, the power amplifier of the first stage of the multi-stage amplifier includes an input matching circuit 141 for transmitting an input signal to a transistor amplifier, a bias circuit (Bias circuit 131a And a transistor amplifier Q1. Here, the transistor amplifier Q1 is a common emitter amplifier in which the emitter of the transistor is grounded. However, the present invention is not limited thereto, and various amplifiers such as a cascade amplifier and the like can be applied.

At this time, since the output OUT of the transistor amplifier Q1 is located in the collector, the output from the collector can be detected. At this time, instead of directly detecting the output current I _C at the collector, the emitter current I _E and the collector current I _C are approximately equal to each other (in the common emitter amplifier circuit of FIG. 7, When the current I _E flowing through the emitter of the transistor amplifier Q 1 is detected using the sum of the current and the collector current as the emitter current and the base current is very small, I _C ).

The current I _E flowing in the emitter can be monitored by monitoring the voltage V _E applied to the resistor R _Det1 connected to the emitter. Therefore, it is also possible to detect the output from the collector by detecting the voltage V _E applied to the emitter.

It is also possible to use a method capable of predicting the output current I _C by monitoring the base voltage V _Det1 of the transistor amplifier Q1.

It is also possible to short the resistor R _Det1 connected to the emitter of FIG. 7 and to monitor the base voltage V _Det1 to detect the output current I _E.

On the other hand, the operating point of the transistor amplifier Q1 can be set by stably supplying a voltage to the base voltage V _Det1 through the bias circuit 131a. As shown in Fig. 7, the three transistors Q2, Q3 and Q4 ) And an RC circuit can be used to supply a voltage corresponding to a desired operating point to the base voltage. However, as described above with reference to FIG. 3, if the power supply voltage of the first stage is fixed to 2.5 V, the final output may be limited and a linearity problem may arise. Therefore, by providing the Darlington circuit to the bias circuit 131a, the linearity problem can be solved. Because the Darlington circuit can supply a large current with high current amplification, the current supplied to the transistor amplifier Q1 can also greatly increase.

Hereinafter, a configuration in which the Darlington circuit is applied to the bias circuit will be described.

FIG. 8 is a circuit diagram in which a Darlington circuit is applied to the bias circuit in FIG. 7; FIG.

Referring to FIG. 8, the bias circuit 131b to which the Darlington circuit is applied can be configured by changing to a Darlington circuit to which two transistors of the same polarity are connected to the transistors Q2 to Q4 of FIG. That is, the bias circuit 131b in which the transistor Q2 in FIG. 7 is changed to Q2 and Q2 ', the transistor Q3 in FIG. 7 is changed to Q3 and Q3', and the transistor Q4 in FIG. 7 is changed to Q4 and Q4 ' .

Hereinafter, the experimental results of comparing the differences between the bias circuit 131a in FIG. 7 and the bias circuit 131b using the Darlington circuit in FIG. 8 will be described.

FIG. 9 is a graph of a simulation test result in which the circuits of FIG. 7 and FIG. 8 are compared with each other.

Referring to FIG. 9, after the resistor R _Det1 connected to the emitter of FIG. 7 is short-circuited, the output (V _Det1 ) of the transistor amplifier Q1 is applied to the base of the transistor amplifier Q1 OUT) the current generated in the collector (I _conv) and a current generated at the output of the collector of the transistor amplifier (Q1) by the voltage (V _be1) is applied to the base of the transistor amplifier (Q1) in Fig. 8 (I _dar ) Are compared with each other.

At this time, the left graph 9a of FIG. 9 shows the collector current obtained through the circuit of FIG. 7, and the right graph 9b shows the collector current obtained through the circuit of FIG.

(Horizontal axis) where the output power changes from 0 dBm to 24 dBm, the collector current in the left graph 9a is changed from 84 mA to 98 mA, and the collector current in the right graph 9b is changed from 78 mA to 103 mA I could confirm.

That is, according to the right graph (9b) to which the Darlington circuit is additionally applied, the linearity can be sufficiently secured since the output power has a smaller output current than the left graph (9a) in a small region of 18 dBm or less.

According to the right graph 9b, the output current is larger than the left graph 9a in a large region where the output power is 24 dBm or more. Therefore, even if the voltage supplied to the power amplifier (for example, the voltage VCC1 supplied to the power amplifier at the first stage) is lowered as shown in FIG. 7, a larger output current can be output at the front end of the final stage. The linearity can be prevented from being lowered.

As a result, even if the power supply voltage of the first stage circuit is lowered, the output power can be supplied to the first main transistor larger than 24 dBm. This can improve the linearity or the maximum output given above.

In addition, the circuit of Fig. 8 can be modified in various ways. The Darlington circuit shown in FIG. 8 can be applied to some of the Darlington circuits, and some of the other transistors can be used as a general transistor. Also, the main transistor may be configured as a Darlington circuit, or may be a cascade type transistor.

Using the multi-stage amplifier to which the adaptive power supply voltage according to the present invention is supplied, the power consumption can be minimized while satisfying the linearity required in the system. The effect of the present invention can be clearly shown in an RF system used in mobile communication. In particular, the present invention can be directly applied to a power amplifier implemented in an integrated circuit or a power amplifier manufactured in a hybrid configuration. In addition, although only bipolar transistors are mainly described in the drawings, the same effect can be applied to FET transistors.

The methods according to the present invention can be implemented in the form of program instructions that can be executed through various computer means and recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions recorded on the computer readable medium may be those specially designed and constructed for the present invention or may be available to those skilled in the computer software.

Examples of computer-readable media include hardware devices that are specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions may include machine language code such as those produced by a compiler, as well as high-level language code that may be executed by a computer using an interpreter or the like. The hardware devices described above may be configured to operate with at least one software module to perform the operations of the present invention, and vice versa.

Also, the above-described method or apparatus may be implemented by combining all or a part of the configuration or function, or may be implemented separately.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

Claims (1)

In a multi-stage amplifier adaptively supplied with a power supply voltage,
A plurality of power amplifiers for sequentially amplifying and outputting an input signal through a plurality of steps;
A detector for detecting an output of a power amplifier belonging to a selected one of the plurality of steps; And
And a voltage controller adapted to adaptively supply a voltage to be applied to the power amplifier belonging to one of the last stages of the plurality of stages in accordance with the output detected by the detector.

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