JP2012004821A - Radio-frequency amplifier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an envelope tracking radio-frequency amplifier that can suppress gain degradation even if an envelope of an input modulation signal has a wide dynamic range.SOLUTION: A modulation power supply circuit 100 comprises: a modulation power supply 120 which adjusts an output voltage according to a modulation power supply control signal corresponding to an envelope signal; a first radio-frequency device 140 that operates optimally in a first voltage region where the output voltage is high; a second radio-frequency device 150 that operates optimally in a second voltage region where the output voltage is lower than the first voltage region; an input RF switch 160 and an output RF switch 170 that switch one of channels and output signals of the first radio-frequency device 140 or the second radio-frequency device 150; a signal generation part 112 that generates a switching signal capable of controlling the input RF switch 160 and the output RF switch 170.

Description

  The present invention relates to a high frequency amplifier, and more particularly to improvement of gain in an ET (Envelope Tracking) type high frequency power amplifier.

  In recent years, there has been a strong demand for higher efficiency of high-frequency high-power amplifiers typified by base station amplifiers for mobile communications. As one method of this solution, a high-frequency amplifier configured by an envelope tracking method has been studied.

  The envelope tracking method is a technique related to high efficiency of a high frequency amplifier. In the envelope tracking method, the power supply voltage supplied to the high-frequency device is changed in accordance with the envelope of the input modulated wave to eliminate useless power and increase the operation efficiency of the high-frequency device.

  FIG. 1 is a diagram showing a basic configuration of an envelope tracking system.

  As shown in FIG. 1, an envelope tracking type high-frequency amplifier 10 includes an envelope signal generation unit 11a, a baseband signal processing unit 11 that generates an RF modulation signal and an envelope signal, and an output voltage according to the envelope signal. A variable modulation power supply 12, a high frequency device 13 driven by an output voltage from the modulation power supply 12, and an RF output terminal 14 are provided.

  Note that the operation principle of the normal envelope tracking method is well known to those skilled in the art from documents such as Non-Patent Document 1, and detailed description thereof will be omitted.

  As is generally known, a high-frequency device has a unique voltage range for optimal operation. If the power supply voltage is raised above that voltage range, the device may be destroyed, and if it is lowered, the gain is greatly reduced.

  FIG. 2 is a diagram illustrating gain characteristics due to voltage fluctuations of the high-frequency device.

  Due to these characteristics, when the dynamic range of the envelope of the input modulation signal is large and the voltage of the high-frequency device is lowered to a voltage that is less than the optimum operating voltage range that can keep the gain constant, it is natural that the operation of the high-frequency device The gain is greatly reduced. The gain reduction of the high frequency device increases the linear distortion of the device. Furthermore, the saturation output required for the drive amplifier is increased, and the power rank of the high-frequency device used for the drive amplifier is increased, resulting in an increase in the cost of the apparatus.

  To solve this problem, for example, as shown in Non-Patent Document 2, the high frequency device is operated in an envelope tracking operation in a voltage range higher than a certain threshold voltage, and the power supply voltage has a good linear characteristic in a low voltage region where the gain of the high frequency device decreases. An envelope tracking operation that is fixed to a class A or class AB bias has been proposed.

  FIG. 3 is a diagram showing a characteristic curve of the supply voltage in the envelope tracking method.

  According to this envelope tracking method, since the voltage range in which the gain of the high-frequency device decreases is not used, an envelope tracking operation with a small gain decrease is possible.

Andrew Grebennikov, “RF and Microwave Power Amplifier Design”, McGRAW-HILL p361-365 Timo Rautoo, Henri Harju, Simo Hietakagans and Timo Rahkoen. Effects of Differentiate VDD-drives in ET & EER Transmitters. In Norchip Conference, 2007.25th, Page 1-4, Nov. 2007.

  However, according to the technique described in Non-Patent Document 2, although a decrease in gain of the high-frequency amplifier can be suppressed, the dynamic range of the envelope of the input modulation signal is large, and the threshold voltage is less than or equal to the threshold voltage operating in class A or class AB. When the operating time increases, there is a problem that wasteful power consumption increases and the apparatus efficiency deteriorates.

  That is, in the conventional envelope tracking method, there is no recognition of the problem that the gain of the high-frequency amplifier decreases when the power supply voltage is set to a low voltage, and no countermeasure is taken. For this reason, there are the following problems.

  (1) The gain of the PA (power amplifier) decreases during low voltage operation.

  (2) Low voltage operation has low gain and poor isolation. This leads to distortion degradation.

  (3) When the gain decreases, the power rank of the drive stage needs to be increased.

  An object of the present invention is to provide an envelope tracking type high frequency amplifier capable of suppressing a decrease in gain even when the dynamic range of an envelope of an input modulation signal is large.

  The high-frequency amplifier of the present invention is an envelope tracking type high-frequency amplifier that varies a power supply voltage supplied to a high-frequency device according to an envelope of an input modulated wave, and fixes the voltage in a voltage region where the gain of the high-frequency device decreases. A modulation power source that varies an output voltage in response to a modulation power source control signal corresponding to an envelope signal, a first high-frequency device that operates optimally in a first voltage region in which the output voltage from the modulation power source is high, and the modulation Device switching for switching between a second high-frequency device that operates optimally in a second voltage region in which an output voltage from a power supply is lower than the first voltage region, and the first high-frequency device and the second high-frequency device And a switching signal generating means for generating a switching signal for switching control of the device switching means.

  According to the present invention, even when the dynamic range of the envelope of the input modulation signal is large, it is possible to select a high-frequency device that operates optimally in accordance with the output voltage range of the modulation power supply, and an envelope that suppresses a decrease in gain. A tracking-type high-frequency amplifier can be realized.

The figure which shows the basic composition of the conventional envelope tracking system Diagram showing gain characteristics due to voltage fluctuations of conventional high-frequency devices The figure which shows the characteristic curve of the supply voltage in the conventional envelope tracking system The figure which shows the structure of the high frequency amplifier which concerns on Embodiment 1 of this invention. The figure which shows the gain versus voltage characteristic in the high frequency device structure from which the high frequency amplifier which concerns on the said Embodiment 1 differs The figure which shows an example which segments the voltage area | region of the envelope of the high frequency amplifier which concerns on the said Embodiment 1. The figure explaining the timing which switches the power supply of the high frequency amplifier which concerns on the said Embodiment 1 The figure which shows an example of a structure of the input RF switch of the high frequency amplifier which concerns on the said Embodiment 1. The figure which shows an example of the input RF distribution ratio of the high frequency amplifier which concerns on the said Embodiment 1. The figure which shows the structure of the high frequency amplifier which concerns on Embodiment 2 of this invention. The figure which shows the gain vs. voltage characteristic in the different high frequency device structure of the high frequency amplifier which concerns on the said Embodiment 2. The figure which shows an example which segments the voltage area | region of the envelope of the high frequency amplifier which concerns on the said Embodiment 2.

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

(Embodiment 1)
FIG. 4 is a diagram showing the configuration of the high-frequency amplifier according to Embodiment 1 of the present invention. The present embodiment is applicable to an envelope tracking type high frequency power amplifier.

  As shown in FIG. 4, the high-frequency amplifier 100 includes a baseband signal processing unit 110, a modulation power source 120, a drive amplifier 130, a first high-frequency device 140, a second high-frequency device 150, an input RF switch 160, and an output RF switch 170. And an RF output terminal 180. The drive amplifier 130, the first high frequency device 140, the second high frequency device 150, the input RF switch 160, and the output RF switch 170 constitute an RF amplifier 190.

  The baseband signal processing unit 110 includes an envelope signal generation unit 111 and a switching signal generation unit 112.

  The baseband signal processing unit 110 generates an RF modulation signal based on the input modulation signal and outputs the RF modulation signal to the RF amplifier 190. The envelope signal generation unit 111 generates a modulated power supply control signal based on the input modulation signal and outputs the modulated power supply control signal to the modulated power supply 120.

  The switching signal generator 112 generates an RF switch control signal based on the input modulation signal, and outputs the RF switch control signal to the input RF switch 160 and the output RF switch 170 via the modulation power source 120. The RF switch control signal is a switching signal that controls the input RF switch 160 and the output RF switch 170 to switch the high-frequency device. The switching signal generation unit 112 generates an RF switch control signal (switching signal) for switching to the second high frequency device 150 having a low operating voltage in a low voltage region where the gain of the first high frequency device 140 decreases.

  In FIG. 4, the baseband signal processing unit 110 is configured to include the switching signal generation unit 112, but the modulation power source 120 may be configured to include the switching signal generation unit 112.

  The modulation power supply 120 amplifies the envelope signal to the power supply voltage of the high frequency device. The modulation power source 120 is controlled by a modulation power source control signal corresponding to the envelope signal, and supplies an output voltage variable according to the modulation power source control signal to the high frequency device (the first high frequency device 140 or the second high frequency device 150). .

  The drive amplifier 130 amplifies the power of the RF modulation signal output from the baseband signal processing unit 110.

  The first high-frequency device 140 operates optimally in the first voltage region where the output voltage from the modulation power supply 120 is high.

  The second high-frequency device 150 operates optimally in the second voltage region where the output voltage from the modulation power source 120 is lower than the first voltage region.

  The first high-frequency device 140 and the second high-frequency device 150 are high-frequency devices having different operating voltages. In general, different device structures have different operating voltages. For example, the first high-frequency device 140 is a GaN device, and the second high-frequency device 150 is an LDMOS (Laterally Diffused MOS). Even in the same device structure, the optimum operating voltage range can be changed by matching adjustment. GaN (gallium nitride) is also called gallium nitride.

  The input RF switch 160 switches the passage path of the RF modulation signal output from the baseband signal processing unit 110 to the first high frequency device 140 or the second high frequency device 150.

  The output RF switch 170 selects the output signal of either the first high frequency device 140 or the second high frequency device 150.

  For the RF switches 160 and 170, it is preferable to use RF-MEMS (Micro Electro Mechanical Systems) with low loss and high isolation.

  Hereinafter, the operation of the high-frequency amplifier 100 configured as described above will be described.

  First, the basic concept of the present invention will be described.

  In the envelope tracking method, the power supply voltage is varied at a voltage equal to or higher than a certain threshold value, and the voltage is fixed in a voltage region where the gain of the high-frequency device decreases. Generally, the gain of the device is lowered when the power supply voltage is lowered, and therefore the gain at the time of fixed low voltage operation is low.

  In addition, the optimum voltage of the high-frequency power device varies depending on the element. For example, 12V is generally known for GaAs devices, 28V for LDMOS, and 50V for GaN devices.

  In the present embodiment, in the envelope tracking method, switching to a high-frequency device with a low operating voltage is performed in a low-voltage region where the gain of the high-frequency device decreases.

  Specifically, the high-frequency amplifier 100 includes a first high-frequency device 140 that supports high-voltage operation, a second high-frequency device 150 that supports low-voltage operation, and the first high-frequency device 140 or the second high-frequency device. An input RF switch 160 and an output RF switch 170 (device switching means) for switching one of the passage paths and output signals of the device 150, and a switching signal generation for generating a switching signal for switching control of the input RF switch 160 and the output RF switch 170 Unit 112. The switching signal generation unit 112 generates an RF switch control signal (switching signal) for switching to the second high frequency device 150 having a low operating voltage in a low voltage region where the gain of the first high frequency device 140 decreases.

  Next, the operation of the high frequency amplifier 100 based on the above basic concept will be described.

  The basic configuration and operation of the modulation power supply circuit 100 according to the present embodiment are the same as those of the conventional modulation power supply circuit of the envelope tracking system.

  As shown in FIG. 4, the baseband signal processing unit 110 generates a modulated power supply control signal, an RF switch control signal, and an RF modulated signal based on the input modulated signal. The switching signal generation unit 112 of the baseband signal processing unit 110 generates an RF switch control signal (switching signal) by analog monitoring of the power supply voltage.

  The RF modulation signal output from the baseband signal processing unit 110 is power-amplified by the drive amplifier 130 constituting the RF amplifier 190 and input to the input RF switch 160.

  The modulation power source 120 is controlled by a modulation power source control signal corresponding to the envelope signal from the baseband signal processing unit 110, and the output voltage changed according to the modulation power source control signal is changed to the first high frequency device 140 or the second high frequency device. Supply to device 150.

  FIG. 5 is a diagram showing gain versus voltage characteristics in different high-frequency device structures. FIG. 6 is a diagram illustrating an example of dividing the voltage region of the envelope.

  As shown in FIG. 5, the gain characteristics of the high-frequency device are the optimum voltage 12V for the GaAs device and the optimum voltage 28V for the LDMOS, and the power supply voltage range in which the gain is constant is different.

  In the present embodiment, the first high-frequency device 140 is a GaN device, and the second high-frequency device 150 is an LDMOS. As shown in FIG. 6, the second high frequency device 150 is operated in the low voltage operation, and the first high frequency device 140 is operated in the high voltage operation.

  As is generally known, high-frequency amplifiers composed of different device structures, such as GaN devices and LDMOS devices, are very difficult to align delay time and phase characteristics even if they are adjusted to circuits that obtain the same gain. is there. Therefore, even if the operation of switching the two devices continuously with the same gain can be realized in this embodiment, the delay time and the phase characteristic may be discontinuous, which may degrade the performance such as the distortion characteristic of the system. .

  With regard to this problem, as for the delay time, a delay circuit may be inserted into a circuit of a device having a short delay time to align the delay times of both devices. The discontinuity of the phase characteristic is solved by providing distortion compensation such as digital distortion compensation.

  The modulation power source 120 switches between the input RF switch 160 and the output RF switch 170 based on the RF switch control signal from the baseband signal processing unit 110. The modulation power supply 120 switches between the input RF switch 160 and the output RF switch 170 so as to drive the first high-frequency device 140 in the high voltage region and the second high-frequency device 150 in the low voltage region. .

  The input RF switch 160 switches the passage path of the RF modulation signal output from the baseband signal processing unit 110 to one of the first high-frequency device 140 and the second high-frequency device 150, and the output RF switch 170 The output signal of either the first high-frequency device 140 or the second high-frequency device 150 is selected. The RF modulated signal will pass through the path of the selected high frequency device.

  By the way, when a plurality of high-frequency devices are switched and used, the switching cannot be performed with a constant gain unless the device startup is completed instantaneously, and it is difficult to obtain a sufficient effect of the present embodiment.

  With regard to this problem, for example, by providing an overlap time at the switching timing between the high voltage operation power source and the low voltage operation power source output from the modulation power source 120, it is possible to ignore unstable operation at the time of device startup. it can.

  FIG. 7 is a diagram for explaining the timing of switching the power supply, and shows an example of the switching timing of the power supply.

  As shown in FIG. 7, with reference to the time for switching between the input RF switch 160 and the output RF switch 170, the timing between the ON / OFF switching of the low voltage power supply and the timing of the ON / OFF switching of the high voltage power supply is between , Tdelay overlap time is given. If this Tdelay is set to be longer than the time from when the first high-frequency device and the second high-frequency device are stably operated, the gain does not fluctuate due to switching between the two devices.

  Further, as another example of the method, the input RF switch 160 can be solved by adopting the configuration shown in FIG.

  FIG. 8 is a diagram illustrating an example of the configuration of the input RF switch 160.

  As shown in FIG. 8, the input RF switch 160 includes a circulator 161 and an RF attenuator 162 that can adjust return loss steplessly using, for example, a Pin diode controlled by an RF switch control signal.

  FIG. 9 is a diagram illustrating an example of an input RF distribution ratio of the input RF switch 160 of FIG.

  As shown in FIG. 9, the input RF switch 160 continuously controls the distribution ratio of the input RF signal according to the control signal.

  Here, instead of the switch forcibly switching the path, the output RF switch 170 of FIG. 4 uses an RF synthesizer that always synthesizes RF power from both input terminals, such as a Wilkinson type or a coupling type. In this case, the control signal for the output RF switch may not be used.

  By adopting such a configuration, the ratio of the RF modulation signal passing through the circulator 161 and the power reflected back to the circulator 161 continuously varies in accordance with the amplitude voltage level of the envelope. That is, since the ratio of the power distributed to the input to the first high-frequency device and the input to the second high-frequency device is adjusted in a stepless manner, the operations of both devices are rapidly switched. There is no point, and it is possible to obtain an RF output in which the gain characteristic change when the device is switched is smoothly synthesized.

  In addition to the power supply switching timing shown in FIG. 7, the configuration of the RF signal path shown in FIG. 8 may be used.

  As described above in detail, according to the present embodiment, the modulation power supply circuit 100 includes the modulation power supply 120 that varies the output voltage in accordance with the modulation power supply control signal corresponding to the envelope signal, and the high output voltage. A first high-frequency device 140 that operates optimally in one voltage region; a second high-frequency device 150 that operates optimally in a second voltage region in which the output voltage is lower than the first voltage region; The input RF switch 160 and the output RF switch 170 for switching the passing path and the output signal of either the high-frequency device 140 or the second high-frequency device 150, and the switching signal for switching the input RF switch 160 and the output RF switch 170 are generated. And a switching signal generation unit 112.

  With the above configuration, even when the dynamic range of the envelope of the input modulation signal is large, it is possible to select a high-frequency device that operates optimally according to the output voltage range of the modulation power supply.

  For example, by making the low voltage region correspond to the second high frequency device 150 that is driven at a low voltage, it is possible to suppress a decrease in gain of the high frequency amplifier 100 in the low voltage region. As a result, the average gain can be improved in the ET operation. The linearity of voltage and gain is improved, and distortion compensation is facilitated. By improving the gain, the isolation of the PA (power amplifier) is improved. By improving the gain, the power rank of the preamplifier can be reduced.

  Further, the cost increase of the member mainly including the addition of the high frequency device according to the present embodiment is much smaller than the reduction amount of the running cost of the apparatus. Even if peripheral components other than the high-frequency device are taken into consideration, the service life of the base station high-frequency amplifier is generally about 10 years, and the amount of reduction in running cost is far greater than the increase in cost of parts.

  Furthermore, as described above, the average operating gain can be improved in this embodiment. If the operating gain is improved by 3 dB, and the rank of the high-frequency device in the preamplifier stage can be lowered from the 3W class to the 1W class, cost reduction can be expected in this respect as well.

  As described above, it is possible to realize an envelope tracking type high-frequency amplifier that suppresses a decrease in gain.

(Embodiment 2)
FIG. 10 is a diagram showing the configuration of the high-frequency amplifier according to Embodiment 2 of the present invention. In the description of the present embodiment, the same components as those in FIG.

  As shown in FIG. 10, the high frequency amplifier 200 includes a baseband signal processing unit 110, a modulation power source 220, a drive amplifier 130, a first high frequency device 140, a second high frequency device 150, an input RF switch 160, and an output RF switch 170. And an RF output terminal 180.

  The modulation power supply 220 amplifies the envelope signal to the power supply voltage of the high frequency device. The modulation power supply 220 is controlled by a modulation power supply control signal corresponding to the envelope signal, and supplies an output voltage variable according to the modulation power supply control signal to the high frequency device (the first high frequency device 140 or the second high frequency device 150). .

  The modulation power source 220 includes a plurality of (four) DC / DC power sources 221 to 224 that amplify the envelope signal to the power source voltage of the high frequency device. Specifically, the modulation power source 220 includes a high voltage DC / DC power source 221 that supplies an output voltage in a high voltage region, a medium and high voltage DC / DC power source 222 that supplies an output voltage in a medium and high voltage region, and a medium and low voltage region. A low-voltage DC / DC power supply 223 that supplies a low-voltage region output voltage, and a low-voltage DC / DC power supply 224 that supplies an output voltage in a low-voltage region.

  Hereinafter, the operation of the high-frequency amplifier 200 configured as described above will be described.

  FIG. 11 is a diagram showing gain versus voltage characteristics in different high-frequency device structures.

  As shown in FIG. 11, it is known that the gain characteristics of a high-frequency device differ depending on the device structure. For example, when a GaN-HEMT (High Electron Mobility Transistor) is used alone as a high-frequency device, the power supply voltage range in which the gain is constant is 25 to 50V. In addition, when the LDMOS is used alone as a high frequency device, the power supply voltage range in which the gain is constant is up to 10 to 25 V, and when the GaAs-HEMT is used as a single high frequency device, the power supply voltage becomes constant. The range is 0-10V. For this reason, when it is desired to achieve an output power of 25 V or less, a configuration for class A or class AB operation may be adopted.

  FIG. 12 is a diagram illustrating an example of dividing the voltage region of the envelope.

  The modulation power source 220 includes a high voltage DC / DC power source 221 that supplies an output voltage in the high voltage region shown in FIG. 12a, a medium / high voltage DC / DC power source 222 that supplies an output voltage in the middle and high voltage region shown in FIG. A medium / low voltage DC / DC power source 223 that supplies an output voltage in the middle / low voltage region shown in FIG.

  As shown in FIG. 12, the modulation power source 220 drives the first high-frequency device 140 when the output voltage is in the middle-high voltage region shown in FIGS. Further, the modulation power source 220 drives the second high-frequency device 150 when the output voltage is in the low voltage region shown in FIG.

  The baseband signal processing unit 110 includes an input RF switch 160 and an output RF so that the modulation power source 220 drives the first high-frequency device 140 in the medium-high voltage region and the second high-frequency device 150 in the low-voltage region. An RF switch control signal for switching the switch 170 is output.

  In the present embodiment, the first high-frequency device 140 is a GaN-HEMT and the second high-frequency device 150 is an LDMOS, so that the power supply voltage range in which the gain of the apparatus is constant is expanded to 5 to 50 V. A high-frequency amplifier 200 of the type can be realized.

  Here, in the case of the middle-high voltage region shown in FIGS. 12a to 12c, the first high-frequency device 140 is a GaN-HEMT, and in the case of the low-voltage region shown in FIG. 12d, the second high-frequency device 150 is an LDMOS. However, the first high-frequency device 140 and the second high-frequency device 150 may be a combination of other device structures that can compensate for a decrease in gain due to voltage fluctuation.

  For example, there is a combination in which the first high frequency device 140 is a GaN device (high voltage operation) and the second high frequency device 150 is an LDMOS (low voltage operation). Further, there is a combination in which the first high-frequency device 140 is a GaN device (high voltage operation) and the second high-frequency device 150 is a GaAs device (low voltage operation). Further, there is a combination in which the first high frequency device 140 is an LDMOS (high voltage operation) and the second high frequency device 150 is a GaAs device (low voltage operation). In addition, the same effect can be obtained by combining devices having different operating voltages.

  Further, the combination of GaN-HEMT and GaAs-HEMT has an advantage that Vgs can be shared.

  The above description is an illustration of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this.

  In each of the above embodiments, an example in which a compound semiconductor device is used as the MESFET (Metal Semiconductor FET) or the transistor has been described, but any transistor may be used. For example, a MIS (Metal Insulated Semiconductor) or MOS (Metal Oxide Semiconductor) transistor may be used. The MIS transistor may be a MIS transistor formed on a silicon substrate having an SOI (Silicon on Insulator) structure. Furthermore, HEMT, BT (Bipolar Transistor), or a combination thereof may be used. However, it goes without saying that compound semiconductor devices are advantageous in terms of power gain in a high frequency range.

  In each of the above embodiments, the first high-frequency device 140 and the second high-frequency device 150 have been described by taking transistors having different device structures as an example, but the same structure in which the optimum operating voltage range is changed by matching adjustment. A combination of high frequency devices may be used.

  In each of the above embodiments, the switching operation is performed in two stages using two high-frequency devices. However, n high-frequency devices are used, and the input RF switch 160 and the output RF switch 170 are configured by n contacts. The high frequency device may be configured and operated in multiple stages. With this configuration, it is possible to realize an envelope tracking type high-frequency amplifier having a wider constant gain operation range.

  In each of the above embodiments, the baseband signal processing unit 110 includes the switching signal generation unit 112. However, the RF switch control signal for controlling the input RF switch 160 and the output RF switch 170 is the modulation power source 120. , 220.

  In FIG. 10, the modulation power source 220 is shown as an example of four DC / DC power sources 221 to 224, but other configurations having the same function may be used. In addition, the number and the voltage region are arbitrary.

  In each of the above embodiments, the name “high frequency amplifier” is used. However, this is for convenience of explanation, and may be an RF power amplifier, a high frequency power amplifier, or the like.

  Furthermore, each circuit unit constituting the high-frequency amplifier, for example, the type of the RF switch, the type and the number of stages of the high-frequency device, are not limited to the above-described embodiment. Of course, various compensation circuits may be added to the high-frequency amplifier.

  The high-frequency amplifier according to the present invention is useful in an envelope tracking type high-frequency power amplifier. In addition to the envelope tracking type high frequency amplifier, it is also effective for a circuit configuration in which a plurality of rated output electric devices such as an electric motor are switched in accordance with a required output.

DESCRIPTION OF SYMBOLS 100,200 High frequency amplifier 110 Baseband signal processing part 120,220 Modulation power supply 130 Drive amplifier 140 1st high frequency device 150 2nd high frequency device 160 Input RF switch 161 Circulator 162 RF attenuator 170 Output RF switch 180 RF output terminal 190 RF Amplifier 221 High voltage DC / DC power supply 222 Medium high voltage DC / DC power supply 223 Medium low voltage DC / DC power supply 224 Low voltage DC / DC power supply

Claims (10)

A high-frequency amplifier of an envelope tracking system that varies a power supply voltage supplied to a high-frequency device according to an envelope of an input modulation wave, and fixes the voltage in a voltage region where the gain of the high-frequency device decreases,
A modulation power supply that varies the output voltage according to the modulation power supply control signal corresponding to the envelope signal;
A first high-frequency device that operates optimally in a first voltage region where the output voltage from the modulation power supply is high;
A second high-frequency device that operates optimally in a second voltage region in which an output voltage from the modulation power supply is lower than the first voltage region;
Device switching means for switching between the first high-frequency device and the second high-frequency device;
A switching signal generating means for generating a switching signal for switching control of the device switching means;
A high frequency amplifier comprising:   2. The high-frequency amplifier according to claim 1, wherein the switching signal generation unit generates a switching signal for switching to the second high-frequency device having a low operating voltage in a low-voltage region where the gain of the first high-frequency device decreases. The second high-frequency device includes a plurality of devices having different operating voltages,
The high-frequency amplifier according to claim 1, wherein the device switching unit switches between the first high-frequency device and the plurality of devices. With a baseband signal processor,
The switching signal generation means includes an input RF switch that switches a passage path of an RF modulation signal output from the baseband signal processing unit to the first high-frequency device or the second high-frequency device;
An output RF switch that extracts an output signal of either the first high-frequency device or the second high-frequency device;
A high-frequency amplifier according to claim 1.   The high-frequency amplifier according to claim 1, wherein the first high-frequency device and the second high-frequency device have different device structures.   The high-frequency amplifier according to claim 1, wherein the first high-frequency device and the second high-frequency device have the same device structure in which an optimum operating voltage range is changed by matching adjustment.   The high-frequency amplifier according to claim 1, wherein the first high-frequency device is a GaN device, and the second high-frequency device is an LDMOS.   The high-frequency amplifier according to claim 1, wherein the first high-frequency device is a GaN device, and the second high-frequency device is a GaAs device.   The high-frequency amplifier according to claim 1, wherein the first high-frequency device is an LDMOS, and the second high-frequency device is a GaAs device.   The high-frequency amplifier according to claim 1, wherein the first high-frequency device is a GaN-HEMT, and the second high-frequency device is an LDMOS or a GaA-HEMT.

Images