KR20020086126A - Power amplifier having impedance matching circuits of which the base/gate voltage is varied, terminal for mobile communication using the same, and method for improving efficiency relating thereto - Google Patents

Abstract

PURPOSE: A power amplifier having a base/gate voltage variation type impedance correction circuit, a mobile communication terminal using the same, and a method for improving efficiency of the same are provided to vary a base/gate voltage according to an RF signal level and improve efficiency the power amplifier by using an MEMS(Micro Electro Mechanical System) switch type variable impedance. CONSTITUTION: A plurality of base/gate direct current bias voltage supply portions(24-26,26') apply dynamic direct current bias voltage to an active element(23) according to a varied RF input signal. An input and an output switching control signal generation portion(27,27') are connected with the base/gate direct current bias voltage supply portions(24-26,26') to generate control signals(a1.a2 or a1',a2') to any one of an input and an output impedance correction circuit. An input and an output impedance matching portion(28,29,Z1,Z2,or 28',29',Z1',Z2') perform impedance matching operations by receiving a control signal from any one of the input and the output switching control signal generation portions(27,27') and varying an impedance.

Description

POWER AMPLIFIER HAVING IMPEDANCE MATCHING CIRCUITS OF WHICH THE BASE / GATE VOLTAGE IS VARIED, TERMINAL FOR MOBILE COMMUNICATION USING THE SAME, AND METHOD FOR IMPROVING EFFICIENCY RELATING THERETO}

The present invention relates to a device and a method for improving the efficiency of a high output amplifier used in a conventional mobile communication terminal, in particular a circuit for the correction of the matching circuit according to the impedance change of the base / gate voltage change type active element and the movement using the same The present invention relates to a communication terminal and a method for improving efficiency thereof.

RF power amplifiers used in mobile communications using CDMA multiplexing require high linearity to limit modulation accuracy and frequency reproduction. In order to minimize distortion caused by nonlinearity, the power amplifier is operated in class A or class AB. When the power amplifier is operated in class A or class AB, if the power output is lower than the maximum power, the efficiency is also reduced.

However, the output power of the terminal is changed in order to adapt to a variable distance between the CDMA base station and the terminal, multipath and shadow fading. The RF output of the terminal is controlled by using active feedback control in order to limit battery life and interference effects in a wireless communication system. In this case, the probability distribution of the output power of the terminal was recently published as shown in FIG. In this case, the efficiency decreases to 0.1% in the case of Class A with decreasing output, and decreases to 2% in the case of Class AB because it is inversely proportional to the square root.

The present invention relates to a high efficiency power amplifier for overcoming the inefficiency of such a battery, and is described in a paper by Gary Hanington et al. , No. 8, August 1999, pp. 1471-1476). The power amplifier disclosed in the paper shifts the operating point to the left side as the DC bias value is changed as shown in FIG. 2 of the paper when low power is output from the terminal. This is possible because the supply voltage is reduced by a DC-DC converter as shown in FIG. 3 of the paper. When the output power of the terminal is reduced, the DC voltage and the current are appropriately changed, thereby reducing the DC bias power, so that the efficiency of the amplifier can be maintained relatively high. Such an amplifier is called an envelope tracking amplifier.

A circuit having an envelope tracking amplifier supplied with a variable bias DC voltage by the DC-DC converter 1 will be described with reference to FIG.

After the RF input is input from the RF signal input terminal 7 and amplified by the power amplifier 10, the amplified RF output is output through the antenna 8. Meanwhile, the power amplifier 10 includes a MESFET 13, and is connected to an RF input terminal through a terminal P1 and an antenna through a terminal P2. In addition, the terminal P1 is connected to the input matching circuit 11. It is connected to the terminal P4 and the antenna.

An input matching circuit 11 is connected to the gate of the MESFET 13 and an output matching circuit 12 is connected to the drain side of the MESFET 13, and the gate and the drain of the MESFET 13 simultaneously connect the terminal P3. Vgg voltage supply 6 (Vbb voltage supply for bipolar transistors) to supply a Vgg bias voltage via Vdd voltage supply 1 (Vcc voltage for bipolar transistors) to supply Vdd bias voltage through terminal P2. Supply unit). It is preferable that AC blocking inductors L1 and L2 are inserted between the Vgg voltage supply part 6 and the Vdd voltage supply part 1 and the terminals P3 and P2, respectively.

On the other hand, a directional coupler 4 is inserted between the RF signal input terminal 7 and the terminal P1 to detect the RF input signal, and the detected input signal is detected by the envelope detector 5. Vdd DC current dependent on the magnitude of the detected envelope signal PD is input as a bias voltage to the drain side of the MESFET 13. The supply 1 of the variable Vdd voltage comprises a DC-DC converter 2, a voltage source 3 therefor, an amplifier, and a plurality of resistor and capacitor elements as shown in FIG. 3.

Therefore, when the output power of the terminal decreases, as shown in FIG. 3, the DC bias power is reduced by appropriately changing the DC voltage and the current, thereby moving the operating point from the point A to the point C, and conversely, the output power of the terminal increases. The operating point moves from point C to point A to improve the efficiency of the terminal.

In addition, as the demand for personal communication devices using wireless communication, such as mobile communication and satellite communication, expands gradually, the quality of wireless communication services is also required to be miniaturized, diversified, wideband, and high quality. The biggest problem with this evolving wireless service is the short battery life. In addition, the size and capacity of the battery is limited compared to the miniaturized terminal. Currently, high power amplifiers (PAMs) within a terminal are known to consume 60% to 70% of the terminal's total DC power. In particular, when the CDMA signal is operated at a low point to increase efficiency, ACPR (Adjacent Channel Power Ratio) characteristics deteriorate drastically due to so-called spectral regrowth, and modulation accuracy is a secondary effect. Tends to fall. In general, since IMT-2000 uses CDMA technology for both W-CDMA and CDMA2000, the amplifier circuit is designed to operate at operating point AB to satisfy ACPR characteristics and efficiency.

On the other hand, when the RF signal output from the terminal arrives at the base station, the output is automatically adjusted in the terminal to always arrive at a constant signal. In addition, due to the changing distance between the terminal and the base station, shadow fading, etc., it is reported that the output level output from the terminal is around 0 dBm, and the probability of outputting the maximum output is about 1%. Recently, the probability distribution function of this output level has been published. Currently used power amplifiers are more likely to output low power, but in practice they have a high loss of efficiency because their operating point is fixed by a high bias voltage. The envelope tracking amplifier as described above attempts to prolong the battery life by increasing the efficiency at low power levels by adjusting the bias voltage low when output at such a low power level. In the high power amplifier of the third generation mobile communication terminal such as IMT-2000, both CDMA2000 and W-CDMA are operated in Class AB using CDMA, so the envelope tracking amplifier is very interesting in that it will dramatically increase the efficiency in the future. It is thought to turn off.

However, due to the dynamic bias of the envelope tracking amplifier, the input and output impedance of the amplifier change according to the magnitude of the RF power signal. This change in impedance reduces the gain of the envelope tracking amplifier, reducing efficiency, worsening VSWR, and worsening stability, causing frequent breakage or damage of the power amplifier. Moreover, the DC-DC converter has a disadvantage in that the ground characteristics are not good and the size and power loss are large.

That is, as shown in Figure 2, when the RF input signal is applied, the signal is input to the envelope detector (Envelope Detector) and the power amplifier, respectively by the coupler. The RF signal entering the envelope detector is converted to direct current. Because of its small size, these DC signals cannot drive direct power amplifiers. The next stage, the DC-DC converter, converts the power amplifier to a dynamic bias that can drive it. In other words, the appropriate bias operating point is adjusted using the DC-DC converter according to the power size. However, if the amplifier's matching point is set at a low power level, a mismatch occurs for the high power level. This mismatch at high power results in lower efficiency and lower gain in high power signals. In addition, when a DC-DC converter is used in an existing envelope tracker, the DC-DC converter uses pulse width modulation (PWM), which causes many features. In other words, if the RF power is largely output, the internal transistor of the DC-DC converter causes a saturation state to be a pulse wave, so that the DC-DC conversion efficiency is theoretically 100%. However, when a low output, which is the RF signal power, which is most frequently used, is output, the internal transistor is not converted to a saturation state and loses the shape of the pulse wave, which tends to drastically reduce the conversion efficiency. In addition, since a signal having a strong modulation frequency is output together with the output DC signal, a low pass filter is required at the output terminal. In this case, the size of the lowpass filter is too large. Even if the DC signal passes through the filter, the output DC signal of the DC-DC converter is too large, so that a weak modulation frequency still exists, which deteriorates the ACPR characteristic of the power amplifier. do. In addition, the DC-DC converter itself is expensive and the grounding problem is serious because it must go through a semiconductor process such as a power amplifier.

The present invention is to solve the above problems, preferably by using a method using a MEMS switch type variable impedance, by changing the base / gate voltage according to the RF signal level without using a DC-DC converter This is to improve the efficiency of amplifier by using base / gate voltage change type amplifier which improves efficiency of power amplifier.

Further objects and effects of the present invention will become more apparent from the following detailed description of the invention described with reference to the accompanying drawings.

1 shows an actual probability distribution of output power levels of a first conventional mobile communication terminal.

2 is a circuit diagram of an envelope tracking amplifier having a DC-DC converter for improving efficiency of a second conventional mobile communication terminal.

3 illustrates a change in operating point according to a change in DC bias of a second conventional RF amplifier and the RF amplifier according to the present invention.

4 is a circuit for correcting a matching circuit according to an impedance change of a base / gate voltage varying type active device according to an exemplary embodiment of the present invention.

FIG. 5 is a structural diagram of a microelectromechanical system (MEMS) switch of FIG. 4. FIG. 5A shows a switch 'off' state and FIG. 5B shows a switch 'on' state.

FIG. 6 is another embodiment of the input or output impedance changer of FIG. 4.

7 is a circuit for correcting a matching circuit according to a change in impedance of a base / gate voltage varying type active element according to another exemplary embodiment of the present invention.

8 is an example of a power amplifier module (PAM) used for measurement.

9 is an equivalent circuit diagram for impedance measurement of an amplifier according to the present invention using the PAM of FIG. 8.

FIG. 10 is a graph of gain characteristics for output power measured according to FIG. 9.

FIG. 11 is a graph of efficiency characteristics for output power measured according to FIG. 9.

12 is a graph of dissipated DC power and probability distribution function for the output power measured according to FIG. 9.

FIG. 13 is a graph of weighted consumed DC power versus the output power using PDF of Motorola measured according to FIG. 9.

FIG. 14 is a graph of the weighted consumed DC power versus output power using a CDG (Cellular Data Group) measured according to FIG. 9.

<Description of the symbols for the main parts of the drawings>

1: Vdd voltage supply unit 2: DC-DC converter

3: voltage source 4: directional coupler

5: envelope detector 6: Vgg voltage supply

7: RF signal input terminal 8: antenna

10: power amplifier

11 input matching circuit 12 output matching circuit

13: MESFET

21: input matching circuit 22: output matching circuit

23 active element 24 directional coupler

25: envelope detector 26, 26 ': voltage regulator

27, 27 ': switch control signal generator

28, 29: switch for first and second input side impedance correction circuit

28 ', 29': switch for first and second output impedance correction circuit

31: actuator 32: pull-down electrode

33: RF transmission line 34: Gain control signal input terminal

36: dynamic bias voltage circuit 35: reference voltage generator

38, 39: third and fourth input side impedance correction circuit switch

L1, L2: AC Blocking Inductors

A power amplifier having a base / gate voltage variable impedance correction circuit, which is an aspect of the present invention, includes a base / gate DC bias voltage supply unit 24 that applies a dynamic DC bias voltage to an active element 23 with respect to a changing RF input signal. -26, 26 ', 34-36, 36'); And a control signal a1, a2 or a1 ', a2' to at least one of the input and output impedance correction circuits, respectively, connected to the DC bias voltage supply units 24-26, 26 ', 34-36, 36'. An input side switching control signal generator 27, an output side switching control signal generator 27 ', or an input / output side switching control signal generator 27, 27'; And an input impedance matching unit 28, 29, Z1, which receives impedance control signals from at least one of the input switching control signal generator 27 and the output switching control signal generator 27 ′, and performs impedance matching by varying impedance. Z2), output impedance matching units 28 ', 29', Z1 ', Z2' or input / output side impedance matching units 28, 29, Z1, Z2 or 28 ', 29', Z1 ', Z2'; It characterized by having a base / gate voltage change type impedance correction circuit for dynamically changing the operating point while matching the impedance of the active element to generate an RF output with improved efficiency.

Preferably, the input impedance matching unit 28, 29, Z1, Z2, output impedance matching unit 28 ', 29', Z1 ', Z2' or input / output side impedance matching unit 28, 29, Z1. , Z2 or 28 ', 29', Z1 ', and Z2' each have at least one impedance Z1, Z2 or Z1 ', Z2' to the input switching control signal generator 27 or the output switching control signal. Switch 28, 29 for impedance correction circuit which is switched in response to switching control signals a1, a2 or a1 ', a2' from generator 27 'or input / output side switching control signal generators 27, 27'. Or 28 ', 29', which is connected to the base / gate of the active element 23. More preferably, the impedance correction circuit switch is a MEMS element.

Also preferably, the DC bias voltage supply unit includes: means for extracting the RF input or output signal; A detector (25) for detecting an envelope signal from the signal extracted by the RF signal extraction means (24); And voltage regulators 26 and 26 'for adjusting the magnitude of the detected signal.

Also preferably, the DC bias voltage supply unit may include: a reference voltage generator 35; And a dynamic bias voltage circuit 36 for generating a bias voltage by comparing the signal of the gain control signal terminal 34 with the reference signal from the reference voltage generator.

On the other hand, the mobile communication terminal which is another aspect of the present invention is characterized by improving the efficiency by using the power amplifier.

Furthermore, another aspect of the present invention provides a method for improving the efficiency of a power amplifier, comprising: (a) a base / gate DC bias voltage supplying step of applying a dynamic DC bias voltage to an active element 23 for a changing RF input signal; (b) issuing a control signal (a1, a2 or a1 ', a2') to at least one of the input and output impedance correction circuits respectively by the bias voltage in the voltage supply step; And (c) performing impedance matching by varying an input side, an output side, or an input / output side impedance by being controlled according to the issued control signal. By including, by varying the operating point while matching the impedance of the active element is characterized in that for generating an RF output with improved efficiency.

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

First, an amplifier having a base / gate voltage varying impedance correction circuit according to the present invention, unlike a conventional envelope tracking amplifier, uses a directional coupler 24 and an envelope detector 25 on the base / gate side without using a DC-DC converter. Are connected to the voltage regulators 26 and 26 '. Therefore, as shown in FIG. 3, the DC voltage proportional to the value according to the power level is used by using the directional coupler 24 and the envelope detector 25 to extract the DC voltage proportional to the signal. To derive This DC voltage is applied to the appropriate bias voltage by the voltage regulator 26 to supply a base / gate by supplying a DC voltage proportional to the changing RF power signal through the coupling inductor L1 to the gate of the MOSFET 23. By changing the current, the power consumption of the PAM is reduced.

In this case, the base / gate voltage change ranges from 2.7V to 3.0V for the products currently used commercially (the highest domestic market share in the case of 'Conexant' RM914: CDMA method). That is, when the RF signal power is low, the base / gate voltage is operated at 2.7V, and when the RF signal power is high, it is operated at 3.0V. It can be used to prevent unnecessary power consumption when low power is output.

However, even in this case, the change in the impedance of TR due to the change in the power of the RF signal should be corrected. In the present invention, as shown in FIG. On the side, change to Z ₁ and Z _2, and on the output side to Z ₁ 'and Z ₂ ' to correct the impedance.

Specifically, the input first impedance Z1 and the second impedance Z2 are respectively connected to the gate terminal P3 of the MOSFET 23 through the switches 28 and 29 for the first and second input side impedance correction circuits, respectively. The output side first impedance Z1 'and the second impedance Z2' are connected to the output terminal of the MOSFET 23 through the switches 28 'and 29' for the first and second output side impedance correction circuits, respectively. P4). The control terminals of the switches 28 and 29 for the first and second input side impedance correction circuits are connected to the input side switch control signal generator 27, and the control signals a1 and a2 is authorized. Similarly, the control terminals of the switches 28 'and 29' for the first and second output-side impedance correction circuits are connected to the output-side switch control signal generator 27 'from the output-side switch control signal generator 27'. The control signals a1 'and a2' are applied. The input side switch control signal generator 27 and the output side switch control signal generator 27 'are connected to voltage regulators 26 and 26', respectively, and voltage-regulated DC voltage signals Pc and Pc 'are input.

Therefore, when the RF input signal is changed, the gate bias voltage of the MOSFET 23 is adjusted by the first voltage-regulated signal Pc proportional to the RF input signal so as to reduce power consumption. In this case, the input and output side switch control signal generators 27 and 27 'are controlled by the first and second voltage-regulated signals Pc and Pc' proportional to the RF input signal. The control signals a1, a2 and (a1 ', a2') are output to the input side impedance correction circuit switches 28 and 29 and the output side impedance correction circuit switches 28 'and 29', respectively. By turning on / off, the input / output side impedance is adjusted.

The input matching circuit 21 and the output matching circuit 22 are not necessarily required, but are preferably present to simplify the input / output side impedance correction circuit. In addition, a bias voltage Vcc having a fixed magnitude is applied to the drain terminal P2 of the MOSFET 23 through the coupling inductor L2.

Meanwhile, the input / output side impedance correction circuit may be formed as a semiconductor device such as a varistor diode, but is preferably made of MEMS technology. The advantages of MEMS switching devices are that semiconductor devices are known to deteriorate ACPR characteristics due to spectral regrowth problems in CDMA signals due to a sharp drop in IMD characteristics when more than 100mW of power is applied. However, since the MEMS device is a passive device, it is reported that the nonlinear characteristic does not appear. Second, the size of MEMS is known to be extremely small: several hundred micrometers × several hundred micrometers × several micrometers. Third, semiconductor devices such as varistor diodes have a mesa process, which is expensive to manufacture and requires many processing steps. Fourth, semiconductor devices such as varactor diodes have a very limited range of variable capacitance when they are used as variable capacitance. The higher the frequency, the faster the rate of change, and the less the change in the fourth generation mobile communication frequency. . On the other hand, MEMS variable capacitances are reported to vary considerably in the range from 30 to 40 GHz. Fifth, the Q value of the semiconductor device is around 10, but the Q value of the MEMS variable capacitance is reported to be excellent around 100. This means that the device itself consumes very little power.

5A and 5B show a cantilever type structure as an example of a MEMS switching element. FIG. 5A shows a switch 'off' state and FIG. 5B shows a switch 'on' state. It consists of a thin metal strip and a dielectric which at least one end is fixed and the rest over free space. When the bias voltage of the control signal C1 is applied between the actuator 31 and the pull-down electrode 32, electric charges are distributed in the same way as a constant power is generated therebetween. Regardless, the applied voltage causes the actuator 31 to move towards the pull-down electrode 32, where the repulsive force is generated as the structure is bent. When the applied voltage reaches a certain threshold value Vth, the repulsive force can no longer be balanced with the electrostatic force and the cantilever as the actuator suddenly falls to the pull-down electrode and shorts with the RF transmission line 33. On the other hand, when the magnitude of the voltage decreases, when the cantilever returns, this occurs at a voltage much lower than the threshold value Vth. Of course, the MEMS switch can be used in many other forms, such as an air bridge type or a membrane type. This is described in detail in, for example, the paper "RF-MEMS Switches for Reconfigurable Integrated Circuits" (IEEE Transactions on Microwave Theory and Techniques, Vol. 46, No. 11, November 1998) by Elliott R. Brown.

Meanwhile, Z1 and Z2 are not necessarily used as the input / output side impedance correction circuit. As shown in FIG. 6, Z ₁ , Z ₂ , Z ₃ , and Z ₄ have different impedances. Switching banks are used, in particular the switching banks of Z ₁ , Z ₂ , Z ₃ and Z ₄ are four switches 28, 29, 38, and binary binary banks of C ₁ , 2C ₁ , 4C ₁ and 8C ₁ . It is also possible to switch to 39. In this way, much more precise impedance matching is possible.

7 shows a second embodiment of the present invention in which the base / gate bias voltage adjustment is performed using the dynamic bias voltage circuit 36. As shown in FIG.

In this embodiment, the dynamic bias voltage circuit 36 receives a gain control signal from a main control circuit (not shown) of a base station or a terminal through an input terminal 34 from a modem, and from a reference voltage generator 35. The regulated bias DC voltage is applied to the gate terminal P3 of the MOSFET 23 through the inductor L1 to adjust the voltage, and the regulated voltage controls the input and output switches. It is applied to the signal generators 27 and 27 'to perform impedance matching as in the first embodiment.

Therefore, according to the present invention, it is possible to adjust the operating point according to the RF power of the amplifier in a simple manner with a base / gate voltage adjuster without using a DC-DC converter, and also to perform impedance matching with respect to the impedance change generated accordingly. You can do it.

8 is an example of a power amplifier used in the present invention described above, and has a structure of 'RM912' manufactured by 'Conexant'. The structure of the RM912 is an RFIC circuit consisting of two amplifiers. The middle stage of the RFIC cannot insert a variable capacitor. Therefore, matching circuit using varistor diode is connected to input and output of power amplifier. This is possible because mismatches in the middle of the power amplifier are reflected in the input and output parts.

Now, the circuit is configured as shown in FIG. 9 to measure the input and output gain of the power amplifier. First, tuner 1 and tuner 2 are connected to the input and output terminals so that the best gain is obtained when a low RF signal is applied, and the optimum impedance is determined so that the overall gain is the highest. Tuner 1 and tuner 2 are also adjusted to maximize gain for high signals. The reason for using the tuner is that it can be seen that the effect of the MEMS switch variable capacitance, such as the circuit of FIG.

That is, FIG. 9 is an equivalent circuit diagram for impedance measurement of an amplifier according to the present invention using the PAM of FIG. 8, FIG. 10 is a gain characteristic graph for the output power measured according to FIG. 9, and FIG. FIG. 12 is a graph of dissipated DC power and probability distribution function for the output power measured according to FIG. 9, and FIG. 13 is a Motorola measured according to FIG. 9. (Motorola) is a graph of the weighted consumption DC power of the output power using the PDF, Figure 14 is a graph of the weighted consumption DC power of the output power using the CDG (Cellular Data Group) measured according to FIG.

As shown in FIG. 10, when the output power of the power amplifier is less than approximately 15 dBm, the gain of the envelope tracking amplifier (marked in blue ▼) matched at 2.7V is higher than the gain of the general power amplifier (marked in black). On the contrary, the gain of the envelope tracking amplifier becomes lower than 15 dBm. This is because the input and output impedance matching is not more than 15 dBm.

Conversely, the gain of a 3V-matched envelope tracking amplifier (indicated by green ▲) is higher than the gain of a typical power amplifier above approximately 15 dBm, but for the same reason the gain of the envelope tracking amplifier is lower below 15 dBm.

However, in the case of the amplifier according to the present invention (indicated by red ●), the gain acts as an envelope tracking amplifier matched at 2.7V at less than approximately 15 dBm and as an envelope trace amplifier matched at 3V on the contrary above 15 dBm. In this case, matching is achieved in any case, so that the gain is always higher than that of the general power amplifier, and the problem of damage to the device due to RF reflection can be solved.

In addition, the amplifier of the present invention, as shown in Figure 11, in the case of the envelope tracking amplifier matched to 2.7V can avoid the problem that the efficiency is lowered due to mismatch at about 25dBm or more.

Fig. 12 compares the probability distribution of the output power of the conventional envelope tracking amplifier with the amplifier according to the present invention and your consumed direct current power.

In the portion with the highest probability distribution (about -5 dBm to 5 dBm for CDG (indicated by black ■) and around 7 dBm for Motorola amplifier (indicated by red)), the power consumption of the amplifier according to the invention (blue) Denoted by ▼, is only one half of the power consumption of the conventional power amplifier (indicated by the green ▲). On the other hand, when the output power is 10 dBm or more, the power consumption of the amplifier matched at 2.7V (indicated by purple +) can also be seen that the DC power consumption is larger than that of the amplifier according to the present invention due to mismatch.

In terms of power consumption in consideration of the weight applied with Motorola, as shown in Fig. 13, the power consumption of the amplifier according to the present invention (indicated by turquoise + and red ●) is the lowest except for some intervals, and the average value thereof is also the general power. 70% of the power consumption (indicated by black ■) of the amplifier is the lowest.

Also, from the viewpoint of power consumption considering the weight applied with CDG, as shown in FIG. 14, the power consumption (indicated by yellow × and green ▲) of the amplifier according to the present invention is the lowest except for some intervals, and the average value thereof is also It is the lowest as 59.5% of the power consumption (indicated by black ■) of the general power amplifier.

In the present specification, the FET as an active element has been described as an example, but the active element may be applied as it is in the case of a bipolar transistor, in which case Vcc represents a collector bias voltage, and a voltage regulator 26 and a dynamic bias voltage circuit ( 36) adjusts the base bias voltage.

In addition, since the RF input corresponds to the RF output, instead of extracting the RF input signal and performing impedance correction, the same result can be obtained by extracting the RF output signal and performing impedance correction. It will be appreciated by one of ordinary skill in the art that the RF signal can be extracted using other devices, such as a power divider instead of the directional coupler.

Although the present invention has been described above with reference to one embodiment shown in the accompanying drawings, the present invention is not limited thereto, and various modifications may be made within a range easily understood by those skilled in the art. Therefore, the limitation of the present invention should be limited only by the following claims.

As described above, in the conventional mobile communication terminal using the envelope tracking amplifier circuit, there are various problems since the DC-DC converter of the actual mobile communication terminal has been used, and even in the case of a terminal changing the base voltage, the supply varies. Due to the mismatch of the input and output terminals of the power amplifier caused by the voltage has a bad effect on the overall efficiency of the terminal, in the case of the present invention, by adding the input and output impedance matching circuit of a simple configuration, the overall efficiency is reduced due to the impedance matching effect In addition, the battery life is increased by about two times, and the matching coefficient is improved due to the impedance matching, so that the amplifier is stabilized, and the terminal can be made compact.

Claims (7)

Base / gate DC bias voltage supplies 24-26, 26 ', 34-36, 36' for applying a dynamic DC bias voltage to the active element 23 for varying RF input signals; And a control signal a1, a2 or a1 ', a2' to at least one of the input and output impedance correction circuits, respectively, connected to the DC bias voltage supply units 24-26, 26 ', 34-36, 36'. An input side switching control signal generator 27, an output side switching control signal generator 27 ', or an input / output side switching control signal generator 27, 27'; And Input side impedance matching units 28, 29, Z1, and Z2 which receive impedance control signals from at least one of the input side switching control signal generator 27 and the output side switching control signal generator 27 'to perform impedance matching. ), An output impedance matching unit 28 ', 29', Z1 ', Z2') or an input / output side impedance matching unit 28, 29, Z1, Z2 or 28 ', 29', Z1 ', Z2'; And a base / gate voltage varying impedance correction circuit for dynamically changing an operating point while performing impedance matching of the active element to generate an RF output having improved efficiency. The method of claim 1, The input impedance matching unit 28, 29, Z1, Z2, the output impedance matching unit 28 ', 29', Z1 ', Z2' or the input / output side impedance matching unit 28, 29, Z1, Z2 or 28 ', 29', Z1 'and Z2' each have at least one impedance Z1, Z2 or Z1 'and Z2', respectively, in the input switching control signal generator 27 or in the output switching control signal generator 27. ', Or an impedance correction circuit switch 28, 29 or 28' switched in response to the switching control signals a1, a2 or a1 ', a2' from the input / output side switching control signal generators 27, 27 ', 29 ') connected to the base / gate of the active element (23). The method of claim 2, The power amplifier for the impedance correction circuit, characterized in that the MEMS device. The method of claim 1, The DC bias voltage supply unit, Means (24) for extracting the RF input or output signal; A detector (25) for detecting an envelope signal from the signal extracted by the RF signal extraction means (24); And And a voltage regulator (26, 26 ') for adjusting the magnitude of the detected signal. The method of claim 1, The DC bias voltage supply unit, A reference voltage generator 35; And And a bias voltage circuit (36) for generating a dynamic bias voltage based on information obtained from the signal of the gain control signal terminal (34). A mobile communication terminal for improving efficiency by using the power amplifier according to any one of claims 1 to 5. (a) supplying a base / gate direct current bias voltage for applying a dynamic direct current bias voltage to the active element 23 with respect to a changing RF input signal; (b) issuing a control signal (a1, a2 or a1 ', a2') to at least one of the input and output impedance correction circuits respectively by the bias voltage in the voltage supply step; And (c) performing impedance matching by controlling an input side, an output side, or an input / output side impedance by controlling according to the issued control signal; By including The method of improving the efficiency of a power amplifier, characterized in that to generate an RF output having an improved efficiency by dynamically changing the operating point while matching the impedance of the active element.