KR102456842B1 - A multi-stage amplifier in which a power supply voltage is adaptively supplied - Google Patents

Abstract

A multi-stage amplifier to which a power supply voltage is adaptively supplied is disclosed. A multi-stage amplifier to which a power supply voltage is adaptively supplied includes a plurality of power amplifiers sequentially amplifying and outputting an input signal through a plurality of stages, and an output of a power amplifier belonging to a selected stage among the plurality of stages. and a voltage controller adaptively supplying a voltage applied to a power amplifier belonging to one of the previous stages of the last stage among the plurality of stages according to the output detected by the detector. Accordingly, the linearity and power efficiency of the power amplifier can be improved.

Description

A multi-stage amplifier with improved linearity and efficiency by applying an adaptive supply voltage.

The present invention relates to a multi-stage amplifier to which a power supply voltage is adaptively supplied, and more particularly, adaptively applying a power supply voltage to a power amplifier located at the front stages of the last stage in the multi-stage amplifier, and to a bias circuit at the front stages. It relates to a multi-stage amplifier with improved linearity and efficiency by applying a Darlington circuit.

As mobile communication technology continues to develop, the demand for a power amplifier that increases 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 a frequency of 20 GHz or higher. An important part in developing a power amplifier suitable for 5G mobile communication is that it should operate linearly up to the average output power of the power amplifier. In addition, the efficiency of the power amplifier becomes important for low-power operation.

On the other hand, in general, a multi-stage amplifier refers to an amplifier having a structure in which a signal initially input is sequentially amplified through a process in which a plurality of amplifiers are connected in series and the output of the front-end amplifier is input to the downstream amplifier.

At this time, the multi-stage amplifier may be configured in the form of two or three stages according to its purpose. it is necessary to do

However, the existing multi-stage amplifier provides a fixed power supply voltage as the power supply voltage applied to each stage of the power amplifier, so there is a problem in that power efficiency is lowered and linearity is lowered.

An object of the present invention for solving the above problems is to provide a multi-stage amplifier to which a power supply voltage is adaptively supplied.

The present invention for achieving the above object provides 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 amplifying and outputting an input signal in series through a plurality of stages, and a power amplifier belonging to a selected stage among the plurality of stages. It may include a detector for detecting an output, and a voltage controller for adaptively supplying a voltage applied to a power amplifier belonging to one of the previous stages of the last stage among the plurality of stages according to the output detected by the detector.

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

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

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

Here, the detector may detect a current flowing through an emitter of a transistor constituting the power amplifier belonging to the selected stage.

Here, the detector may detect a voltage applied to an emitter of a transistor constituting a power amplifier belonging to the selected stage.

Here, the detector may detect the voltage applied to the base by shorting the emitter of the transistor constituting the power amplifier belonging to the selected stage.

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

Here, the multi-stage amplifier may further include a plurality of bias circuits for setting an operating point of 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 among the plurality of bias circuits may be configured as a Darlington circuit in which two transistors of the same polarity are connected.

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

In particular, the present invention has the advantage that it can have a greater effect in the RF system used in mobile communication, and can be directly applied to a power amplifier implemented in an integrated circuit or a power amplifier manufactured in a hybrid form.

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

Since the present invention can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. In describing each figure, like reference numerals have been used for like elements.

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

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It is to be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, 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 a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does 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 composed of two stages.

Referring to FIG. 1 , as an exemplary configuration of a multistage amplifier, the first stage amplifier (1 ^st stage) having an input matching circuit (input MC), the first stage amplifier (1 ^st stage) output and Inter-stage Matching Circuit (Inter MC) connected between the input of the second stage amplifier (2 ^nd Stage) and the second stage amplifier (2 ^nd Stage) having the output of the intermediate matching circuit (Inter MC) as input and an output matching circuit (Output MC) connected to the output of the second stage of the amplifier ( ^2nd Stage) can be described as a two-stage power amplifier. At this time, although a two-stage power amplifier is exemplified in FIG. 1 , it should be interpreted that it can be applied to a power amplifier composed of more stages according to a desired application field.

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

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

The second stage of the amplifier ( ^2nd stage) is a power amplifier (PA) and can generate a high output 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 and VCC2 and the reference voltages Vref1 and Vref2 that can determine the operating point, respectively. .

On the other hand, the power amplifier efficiency (Power Amplifier Effiency) 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 . At this time, since the last 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 depending on the power amplifier operating range, or the power supply voltage of the final stage is changed in real time according to the input RF signal. The efficiency of the amplifier can be improved.

1, since the final stage becomes the second stage, change the power supply voltage (VCC2) of the amplifier of the second stage according to the operating range (eg, select one of 2V, 3V, 4V, 5V), or It can be changed according to the output RF signal. At this time, as a means or method for changing, the power supply voltage can be changed in real time by using a switch, switching the power supply voltage, or using envelope tracking (ET) technology.

FIG. 2 is a graph comparing an ET technique for changing a supply voltage according to an output waveform envelope with a case where a fixed supply voltage is used.

A graph 2a displayed on the left side of FIG. 2 shows a transmitted RF signal when a fixed voltage (Fixed PA Supply Voltage) is applied as a supply voltage to the power amplifier. Here, the remaining portion except for the RF signal transmitted from the fixed supply voltage may be energy lost due to heat (Dissipated As Heat).

The graph 2b displayed on the right side of FIG. 2 is a graph when the tracking PA supply voltage to the power amplifier is changed according to the waveform of the transmitted RF signal. Comparing with the graph on the left, it can be seen that the energy dissipated as heat, which is the remaining part (shown in red) except for the RF signal transmitted from the supply voltage, is much reduced.

Accordingly, if the supply voltage supplied to the last stage of the power amplifier is changed according to the envelope of the output waveform, the efficiency of the power amplifier may be maximized.

On the other hand, unlike the last stage power amplifier, the amplifier of the first stage (or the previous stages of the last stage) that operates sufficiently linearly generally uses a fixed supply voltage. This is because the power amplifier of the first stage (or the front stages of the last stage) uses a class A amplifier in order to ensure the linearity of the power amplifier located at the rear stage of the first stage (or the front stages of the last stage). However, as the system becomes more complex and is required to handle multi-functions, the front stages of the final stage, not the final stage, consume about 1/2 of the current of the final stage, consuming power that is no longer negligible are doing In particular, the ratio of the quiescent current immediately preceding the final stage to the quiescent current of the final stage may be increased.

Therefore, in order to further improve the efficiency of the power amplifier, the present invention proposes a method of applying a changed power supply voltage in some cases, rather than a fixed voltage, to the amplifier located at the front ends of the final stage. For example, the power supply voltage VCC1 of the power amplifier of the first stage of FIG. 1 may be operated at a lower power supply voltage than before, not a fixed power supply voltage, and a graph of the result will be described below.

FIG. 3A is a graph showing the efficiency of a multi-stage power amplifier when the supply voltage VCC2 to the power amplifier of the second stage is fixed and the supply voltage VCC1 to the power amplifier of the first stage is changed in FIG. 1 . 3B is an enlarged graph of the graph according to FIG. 3A.

Referring to FIG. 3A , the power supply voltage ^VCC2 applied to the second stage of FIG. 1 is fixed at 5V and the power supply voltage VCC1 applied to the first stage of the amplifier is changed while changing the efficiency of the power amplifier. (PAE) was confirmed. Specifically, when the voltage of the power supply voltage (VCC2) applied to the amplifier of the second stage is fixed at 5V and the power supply voltage (VCC1) applied to the amplifier of the first stage is changed to 2.5V, 3.4V, and 5.0V, the output power The power amplifier efficiency (PAE) for As can be seen from the graph, it can be seen that the power amplifier efficiency increases as the output power increases. At full output power, it has a power amplifier efficiency of about 40%. At this time, when the power supply voltage VCC1 applied to the amplifier of the first stage is 2.5V, it can be seen that the efficiency is also limited to 40% or less due to the limitation of the maximum power. In this case, since a general mobile communication terminal is not used at the maximum output point, efficiency in average power is more important.

Accordingly, with reference to FIG. 3B , the efficiencies can be compared at an average output power of 25 dBm. Specifically, when the power supply voltage (VCC1) applied to the amplifier of the first stage is 2.5V, 3.4V, or 5V (expressed as DA2.5V, DA3.4V, DA5V), the power amplifier efficiency (PAE) is 17.8%, 17.1% , 14.9% can be seen.

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

In order to check the linearity characteristic of the power amplifier, it is necessary to check the Adjacent Channel Leakage Power Ratio (ACLR) value. ACLR characteristic compares the RF channel signal of the desired band with the signal of the adjacent band by applying the LTE (Long Term Evolution) signal to the RF input signal to the power amplifier and then analyzing the output RF signal through a signal analyzer. .

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

Here, since adjacent channels exist above and below, respectively, two powers within the bandwidth of the adjacent channels may also exist. Therefore, if ACLR derived by substituting power within the bandwidth of the upper adjacent channel to P _ref is ACLR_upper, and ACLR derived by substituting power in the bandwidth of the lower adjacent channel to P _ref is ACLR_lower, ACLR may be a result of averaging ACLR_upper and ACLR_lower.

Hereinafter, the ACLR value of 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 result of FIG. 3 is derived.

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

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

Considering the power amplifier efficiency (PAE) confirmed in FIG. 3 and the linearity confirmed in FIG. 5, the power supply voltage (VCC1) applied to the first stage power amplifier is 2.5V until the output power of the power amplifier is 24dBm, and the output power It can be seen that applying 3.4V between 24dBm and 25dBm and 5.0V at output power of 25dBm or higher is effective in terms of maintaining power amplifier efficiency and linearity.

That is, if the power supply voltage applied to the power amplifier located in the front stage of the power amplifier located in the last stage is changed based on the output power, the efficiency and linearity of the booster amplifier may 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 an input signal through a plurality of stages, the plurality of Adapting the voltage applied to the detector 111 for detecting the output of the power amplifier belonging to the selected stage among the steps of It may include a voltage controller 122 that supplies the power. At this time, although illustrated as a two-stage amplifier in FIG. 6 , the present invention is not limited thereto.

Comparing FIG. 6 with FIG. 1, the detector 111 and the voltage regulator (or DC voltage regulator, DC regulator, 121 to 122) are additionally configured in the multi-stage power amplifier 101 and 102 composed of two stages in FIG. that can be checked In addition, the first stage power amplifier 101 and the second stage power amplifier 102 have bias circuits (1 ^st Bias Circuit, 2 ^nd Bias Circuit, 131 to 132) to set their respective operating points. can In addition, as in FIG. 1 , the multi-stage amplifier includes an input matching circuit 141 for transferring an input signal to the power amplifier of the first stage, and an intermediate matching circuit 142 for transferring the output of the power amplifier of the first stage to the power amplifier of the second stage. ), an output matching circuit 143 for receiving and outputting the output of the power amplifier of the second stage.

Here, the voltage controller 122 may be a voltage regulator (or a DC voltage regulator, a DC regulator) as shown in FIG. 6 , but may also be a DC/DC converter. In addition, the voltage controller 122 adaptively adjusts the voltage applied to the power amplifier belonging to the immediately preceding stage or the first stage 101 of the final stage (102 is the second stage in the drawing) according to the output detected by the detector 111 . can be supplied with 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 last stage among the plurality of stages to correspond to the waveform of the output signal detected by the detector 111 . Yes (in this case, the ET technique described with reference to FIG. 2 may be applied). Here, when the voltage controller 122 is a DC regulator, it is possible to select and supply a power supply voltage by using a switching circuit among various power supply voltages such as VDD1, VDD2, .. , VDDN.

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

On the other hand, although the detector 111 has been described as detecting the RF output power from the output circuit 143 of the final stage, when the detector 111 is connected to the output circuit 143 of the final stage, the final stage due to the detector 111 There is a possibility that the output will be lowered. Accordingly, the RF output power can be detected at a stage other than the final stage (eg, the front stages of the final stage), and when the RF output power is detected from a stage other than the final stage, the detected RF output power is It can be set differently. For example, the detector 111 may detect the output of the power amplifier belonging to the final stage. Also, the detector 111 may detect the output of the power amplifier belonging to the stage immediately preceding the final stage.

Hereinafter, as one of several examples of detecting an output signal from the previous stages of the final stage, a method of detecting an output signal for a power amplifier of the first stage in a multi-stage amplifier composed of two stages will be described.

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

Referring to FIG. 7 , the power amplifier of the first stage of the multi-stage amplifier includes an input matching circuit 141 that transfers an input signal to the transistor amplifier, and a bias circuit 131a that sets an operating point for the transistor amplifier. ) and a transistor amplifier Q1. Here, the transistor amplifier Q1 is illustrated as an example of a common emitter amplifier in which the emitter of the transistor is grounded, but is not limited thereto, and various amplifiers such as a cascade amplifier may be applied.

At this time, since the output OUT of the transistor amplifier Q1 is located at the collector, it may be necessary to detect the output at the collector. 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 (base in the common emitter amplifier circuit of FIG. 7 ). When the current (I _E ) flowing through the emitter of the transistor amplifier (Q1) is detected using the sum of the current and the collector current becomes the emitter current, and the base current is very small), the collector output current ( I _C ) can be detected.

In addition, the current flowing through the emitter (I _E ) can be known by monitoring the voltage (V _E ) applied to the resistor (R _Det1 ) connected to the emitter. Thus, it is also possible to detect the output at the collector by detecting the voltage V _E applied to the emitter.

Also, a method of predicting the output current I _C by monitoring the base voltage V _Det1 of the transistor amplifier Q1 may be used.

In addition, the output current I _E may be detected by shorting the resistor R _Det1 connected to the emitter of FIG. 7 and monitoring the base voltage V _Det1 .

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

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 of FIG. 7 .

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

Hereinafter, experimental results comparing the differences between the bias circuit 131a in FIG. 7 and the bias circuit 131b in FIG. 8 to which the Darlington circuit is additionally applied will be described.

9 is a graph of simulation test results comparing the circuits of FIGS. 7 and 8 with each other.

Referring to FIG. 9 , after shorting the resistor R _Det1 connected to the emitter in FIG. 7 , the output of the transistor amplifier Q1 by the voltage V _Det1 applied to the base of the transistor amplifier Q1 ( OUT), the current (I _conv ) generated in the collector, and the current (I _dar ) generated in the collector, the output of the transistor amplifier (Q1) by the voltage (V _be1 ) applied to the base of the transistor amplifier (Q1) in FIG. ) can be 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. 8 .

Looking at the part (horizontal axis) where the output power changes from 0dBm to 24dBm, the collector current in the left graph (9a) changes from 84mA to 98mA, and the collector current in the right graph (9b) changes from 78mA to 103mA. could check

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

In addition, according to the graph on the right (9b), in a large region where the output power is 24 dBm or more, the output current is larger than that of the graph (9a) on the left. Therefore, even if the voltage supplied to the power amplifier (for example, the voltage supplied to the first stage, VCC1) is adjusted and lowered as shown in FIG. 7, a larger output current can be output from the front stage of the final stage. It becomes possible to prevent the linearity from being deteriorated.

Through this result, even when the power supply voltage of the first-stage circuit is lowered, the output power exceeds 24dBm and a larger current can be supplied to the first-stage main transistor. This can improve the linearity part or the maximum output suggested earlier.

Additionally, the circuit of FIG. 8 may be variously modified. A part of the transistor configured as the Darlington circuit of FIG. 8 may be applied as a Darlington circuit, and the other part may be applied as a general transistor. In addition, the main transistor may also be configured as a Darlington circuit or as a cascade type transistor.

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

The methods according to the present invention may be implemented in the form of program instructions that can be executed by various computer means and recorded in 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 specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software.

Examples of computer-readable media may include hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions may include not only machine language codes such as those generated by a compiler, but also high-level language codes that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as at least one software module to perform the operations of the present invention, and vice versa.

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

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention as set forth in the claims below. You will understand that it can be done.

Claims (10)

In a multi-stage amplifier to which a power supply voltage is adaptively supplied,
a plurality of power amplifiers 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 stage among the plurality of stages;
a voltage controller adaptively supplying a voltage applied to a power amplifier belonging to one of the previous stages of a final stage among the plurality of stages according to the output detected by the detector; and
a plurality of bias circuits for setting an operating point for at least one of the power amplifiers belonging to the plurality of stages;
including,
The bias circuit is
an output circuit for applying a bias current to at least one input node of the power amplifiers belonging to the plurality of stages; and
a reference circuit including a current mirror for controlling an input current of the output circuit;
including,
The output circuit includes a first Darlington circuit to which two transistors of the same polarity are connected,
and the reference circuit comprises a second Darlington circuit to which two transistors of the same polarity are connected, constituting the current mirror. The method according to claim 1,
The detector is
Detecting the output of the power amplifier belonging to the last stage, multi-stage amplifier. The method according to claim 1,
The detector is
A multi-stage amplifier for detecting the output of a power amplifier belonging to a stage immediately preceding the final stage. The method according to claim 1,
The voltage controller is
A multi-stage amplifier for adaptively supplying a voltage applied to a power amplifier belonging to a stage immediately preceding the final stage. The method according to claim 1,
The detector is
A multi-stage amplifier for detecting a current flowing in an emitter of a transistor constituting the power amplifier belonging to the selected stage. The method according to claim 1,
The detector is
A multi-stage amplifier for detecting a voltage flowing through an emitter of a transistor constituting the power amplifier belonging to the selected stage. The method according to claim 1,
The detector is
Short-circuiting the emitter of the transistor constituting the power amplifier belonging to the selected stage and detecting the voltage applied to the base, the multi-stage amplifier. The method according to claim 1,
The voltage controller is
and adaptively changing a voltage applied to a power amplifier belonging to one of the previous stages of a final stage among the plurality of stages to correspond to the waveform of the output signal detected by the detector. delete delete

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