KR101049649B1 - Multipath Doherty Amplifier and its Control Method - Google Patents

Abstract

The present invention provides a multipath Doherty amplifier and a control method thereof, comprising: a multiple input switch configured to receive and switch a plurality of input signals; A carrier amplifier for carrier amplifying the signal of the multiple input switch; A first 90 degree phase shifter for shifting the output of the carrier amplifier 90 degrees; Second to N-th 90 degree phase shifters which respectively phase shift the signals of the multiple input switch; First to N-th peak amplifying units configured to receive the outputs of the second to N-th 90 degree phase shifters and to respectively amplify the peaks; A multiple output switch configured to receive and switch outputs of the first 90 degree phase shifter and the first through N-th peak amplification parts to an antenna; And a gate bias control unit configured to control the second to Nth 90 degree phase shifters such that the outputs of the first to Nth peak amplifiers are equal to the gate biases of the carrier amplifier. And Doherty amplification in multiple paths.

Description

Multipath doherty amplifier and its control method {Apparatus and control method for multi path doherty amplifier}

1 is a block diagram of a conventional Doherty amplifier,

2 is a block diagram of a conventional multi-input Doherty amplifier,

3 is a block diagram of a conventional multiple input and multiple output Doherty amplifier,

4 is a block diagram of a multi-path Doherty amplifier according to an embodiment of the present invention.

5 is a block diagram of a multi-path Doherty amplifier according to another embodiment of the present invention,

6 is a flowchart illustrating a control method of a multipath Doherty amplifier according to an embodiment of the present invention.

FIG. 7 is a conceptual diagram illustrating an application example of the present invention when supporting three sectors in FIG. 5;

FIG. 8 is a conceptual diagram illustrating an application example of the present invention when supporting the 4-path smart antenna in FIG. 5.

Explanation of symbols on the main parts of the drawings

100: carrier amplification unit 210 ~ 240: 90 degree phase shift unit                 

310 to 330: peak amplifier 400 to 430: multiple input switch

500 to 530: Multiple output switch 600: Gate bias control

700 to 740: antenna

TECHNICAL FIELD The present invention relates to a multipath Doherty amplifier and a control method thereof, and more particularly, to a multipath Doherty amplifier and a control method thereof, which are suitable for simultaneously supporting Doherty amplification in a single path and a multipath through switch control.

In general, power amplifiers used in mobile communication systems and mobile communication terminals based on code division multiple access (CDMA) require high linearity and high efficiency. In addition, the high efficiency of the battery occupies an important position in solving the problem of heat generation, which increases the use time of the battery in the terminal and causes considerable inconvenience to the user.

In addition, mobile communication terminals use low output power in most cases, and are increasingly important in efficiently managing and increasing the efficiency thereof.

Among the amplifiers having such high efficiency, the Doherty amplifier is recognized as the most suitable power amplifier for the mobile communication system.

The Doherty amplifier is one of the amplifiers used in the high efficiency modulation scheme of a high power transmitter. The Doherty amplifier improves efficiency by a combination of a class B amplifier, a class C amplifier, and an impedance inversion circuit. Such Doherty amplifiers use a quarter wave transformer (λ / 4 line) to connect a carrier amplifier and a peak or peaking amplifier in parallel.

The peak amplifier (or peaking amplifier) of the Doherty amplifier increases the efficiency by adjusting the load line impedance of the carrier amplifier by varying the amount of current supplied to the load according to the power level.

Ultra-high frequency Doherty amplifier was W. in 1936. H. Proposed by WH Doherty, the early ultra-high frequency Doherty amplifiers are known as Amplitude Modulation (AM) transmitters for broadcast equipment using high-output long-frequency (LF) tubes or high-output medium-frequency (MF) tubes. transmitter).

Since the high frequency Doherty amplifier has been applied to an amplitude modulation transmitter, there have been various proposals for using the high frequency Doherty amplifier in a solid-state high power transmitter, and several schemes have been proposed for practical implementation.

1 is a block diagram of a conventional Doherty amplifier.

Here, reference numeral 10 is a carrier amplifier, 21 and 22 are a plurality of phase shifts of 90 degrees, 31 is a peak amplifier.

Thus, the Doherty amplifier uses a transmission line to connect the carrier amplifier 10 and the peak amplifier 31 in parallel.

The amount of current output from the peak amplifier 31 to the load is changed according to the power level.

Accordingly, the load impedance of the carrier amplifier 10 is adjusted to increase the efficiency. However, Doherty amplifiers are relatively poor in linearity, and their linearity is inversely proportional to the amplifier's efficiency.

Referring to the operation of the conventional Doherty amplifier as follows.

First, the input signal is input to the Doherty amplifier, one of two signals is input to the carrier amplifier 10 and the other signal is a peak amplifier through a second 90 degree phase shifter 22, which is a transmission line. It is input to (31).

At this time, the second 90 degree phase shifter 22, which is a transmission line, compensates the delay time difference with the signal input to the carrier amplifier 10 by delaying the signal input to the peak amplifier 31 by 90 degrees.

The first 90 degree phase shifter 21 delays the signal output from the carrier amplifier 10 by 90 degrees to compensate for the difference between the signal input to the peak amplifier 31 and the delay time.

Accordingly, the output signals from the carrier amplifier 10 and the peak amplifier 31 are combined and output at the common node.

2 is a block diagram of a conventional multiple input Doherty amplifier.

Here, reference numeral 10 is a carrier amplification unit, 21 to 24 are a plurality of 90 degrees phase shift unit, 31 to 33 are a plurality of peak amplification unit.

Thus, the input signal is input to the carrier amplifier 10 and the second to Nth 90 degree phase shifters 22 to 24.

The output of the carrier amplifier 10 is input to the first 90 degree phase shifter 21 and time delayed. The outputs of the second to Nth 90 degree phase shifters 22 to 24 are input to the first to N-1th peak amplifiers 31 to 33, respectively.

The outputs of the first 90-degree phase shifter 21 and the first through N-th peak amplification units 33 are combined and output as one.

3 is a block diagram of a conventional multiple input and multiple output Doherty amplifier.

This shows that a plurality of multiple input Doherty amplifiers of FIG. 2 are connected.

Accordingly, as shown in FIG. 3, the multi-input Doherty amplifier of FIG. 2 is installed as necessary for multiple input and multiple output.

However, this conventional technology has the following problems.

A conventional Doherty amplifier can be configured with a plurality of peak amplification units and a 90 degree phase shifter, but since it has one input and one output, it is necessary to purchase another Doherty amplifier to support multiple paths. There was a problem to be increased.

In particular, when the base station of the mobile communication system upgrades the structure to transmit diversity or smart antenna, the cost increases linearly because an amplifier must be purchased for the number of antennas.

In the case of a smart antenna, at least four antennas can exhibit proper performance. In the case of using the prior art, four or more Doherty amplifiers are required, and the upgrade cost is also increased by four times or more.

 Accordingly, the present invention has been proposed to solve the above-mentioned general problems, and an object of the present invention is to provide a multipath Doherty amplifier capable of simultaneously supporting Doherty amplification in a single path and a multipath through a switch control, and a control method thereof. To provide.

In order to achieve the above object, the multipath Doherty amplifier according to an embodiment of the present invention,

A multiple input switch configured to receive and switch a plurality of input signals; A carrier amplifier for carrier amplifying the signal of the multiple input switch; A first 90 degree phase shifter for shifting the output of the carrier amplifier 90 degrees; Second to N-th 90 degree phase shifters which respectively phase shift the signals of the multiple input switch; First to N-th peak amplifying units configured to receive the outputs of the second to N-th 90 degree phase shifters and to respectively amplify the peaks; A multiple output switch configured to receive and switch the outputs of the first 90 degree phase shifter and the first through N-th peak amplification units to output signals switched by a plurality of antennas; And a gate bias control unit configured to control the second to N-th 90 degree phase shifters such that the outputs of the first to N-1 peak amplifiers are equal to the gate biases of the carrier amplifiers. .

In order to achieve the above object, the control method of the multi-path Doherty amplifier according to an embodiment of the present invention,

Selecting a multi-path input signal; A second step of performing carrier amplification and peak amplification and phase-aligning the selected input signal after the first step; And a third step of outputting the signals switched by the plurality of antennas by switching the amplified power in the multipath after the second step.

Hereinafter, an embodiment according to the present invention, a multipath Doherty amplifier, and a control method thereof will be described with reference to the accompanying drawings.

4 is a block diagram of a multipath Doherty amplifier according to an embodiment of the present invention, and FIG. 5 is a block diagram of a multipath Doherty amplifier according to another embodiment of the present invention.

As shown therein, a multiple input switch 400 for receiving and switching a plurality of input signals; A carrier amplifying unit (100) for receiving carrier signals from the multiple input switch (400) and amplifying carriers; A first 90 degree phase shifter (210) for shifting the output of the carrier amplifier (100) by 90 degrees; Second to Nth 90 degree phase shifters 220 to 240 for phase shifting the signal of the multiple input switch 400 by 90 degrees, respectively; First to N-th peak amplifying units (310 to 330) receiving peaks of the second to N 90 degree phase shifters (220 to 240) and amplifying the peaks; A multiple output switch 500 for receiving and switching the outputs of the first 90 degree phase shifter 210 and the first to N-th peak amplification units 310 to 330 to output an antenna; The second to N th 90 degree phase shifters 220 to 240 are controlled so that the outputs of the first to N-1 peak amplifiers 310 to 330 are equal to the gate bias of the carrier amplifier 100. It is configured to include a gate bias control unit 600.                     

The multiple output switch 500 is characterized in that for outputting a signal switched to a plurality of smart antenna, respectively.

6 is a flowchart illustrating a control method of a multipath Doherty amplifier according to an embodiment of the present invention.

As shown therein, a first step ST10 of selecting an input signal input through a multipath; A second step (ST20) of performing carrier amplification and peak amplification and phase-aligning the selected input signal after the first step; And a third step (ST30) of switching and outputting the amplified power in the multi-path after the second step.

In the third step, the amplified power is switched to multiple paths and output to the plurality of smart antennas, respectively.

The operation of the multi-path Doherty amplifier and its control method according to the present invention configured as described above will be described in detail with reference to the accompanying drawings.

First, the present invention intends to simultaneously support Doherty amplification in a single path and multiple paths through switch control.

Therefore, the carrier amplifier 100 and the peak amplifiers 310 to 330 which are two power amplifiers saturated at different input power levels are used.

This allows one amplifier to reach saturation and peak efficiency before the other amplifier arrives.

Because a power amplifier with a higher output load impedance saturates at a lower output power level, dynamic loading of another power amplifier by one amplifier can change the power output level, at which the loading is saturated and peaked. Efficiency is reached. This characteristic operates the amplifier in saturated mode over the range of output power because the output power increases as the load impedance decreases.

The higher impedance provided to the carrier amplification unit 100 saturates the Doherty amplifier earlier with an optimal load impedance.

When the peak amplification sections 310 to 330 are activated, the finite output impedance of the amplifier is maintained until the carrier and peak amplification sections 100 to 310 to 330 deliver the same power as their respective local load impedances. The load impedance of the carrier amplifier 100 is reduced.

The effects of the carrier amplification unit 100 and the peak amplification unit 310 to 330 delivering the same is that these amplifiers provide more than a decibel (dB) output power than a single amplifier, so that the carrier amplification unit 100 It is intended to saturate earlier than a decibel (dB), so that the efficiency remains at nearly peak saturated efficiency over a range of power ranges.

Meanwhile, the multiple input switch 400 receives and switches a plurality of input signals.

In addition, the multiple output switch 500 receives and outputs the outputs of the first 90 degree phase shifter 210 and the first to N-th peak amplification units 310 to 330 to output them to the antenna. In this case, the antennas 700 to 740 may use a smart antenna.

The gate bias control unit 600 includes the second through N-th 90 degree phase shifters 220 through 330 such that the outputs of the first through N-1 peak amplifiers 310 through 330 are equal to the gate bias of the carrier amplifier 100. 240).

7 is a conceptual diagram illustrating an application example of the present invention when supporting three sectors in FIG. 5, and FIG. 8 is a conceptual diagram illustrating an application example of the present invention when supporting a four-path smart antenna in FIG. 5.

The operation of the present invention will be described in the order of time as follows.

First, the multi-input switch 400 selects a required signal from input signals input through multi-paths.

In addition, the carrier amplifying unit 100 amplifies the power signal input from the multiple input switch 400.

The first 90 degree phase shifter 210 allows the output of the carrier amplification unit 100 to be in phase with the outputs of the first to N-th peak amplification units 310 to 330.

The second to Nth 90 degree phase shifters 220 to 240 receive the respective signals selected and output from the multiple input switch 400 and are controlled by the gate bias controller 600 to control the first to N-1th. The phase shift is performed so that the outputs of the peak amplifiers 310 to 330 are in phase with the outputs of the carrier amplifier 100.

In this case, the gate bias control unit 600 controls the gate bias of the peak amplifiers 310 to 330 to be the same as the gate bias of the carrier amplifier 100.

Then, the first to N-th peak amplification units 310 to 330 receive signals from the second to N-th 90 degree phase shifters 220 to 240, and perform peak amplification.                     

When Doherty power amplification is performed, the multiple output switch 500 outputs the amplified power by switching to the multipath. At this time, the antenna that receives the output signal may use a smart antenna, it can be connected to the smart antenna with only one multi-path Doherty amplifier according to the present invention.

As such, the present invention is to simultaneously support Doherty amplification in single-path and multi-path through switch control.

Although preferred embodiments of the present invention have been described above, the present invention may use various changes, modifications, and equivalents. It is clear that the present invention can be applied in the same manner by appropriately modifying the above embodiments. Accordingly, the above description does not limit the scope of the invention as defined by the limitations of the following claims.

As described above, the multi-path Doherty amplifier and its control method according to the present invention can be used as a power amplifier having a high output at the same time when the base station supports a single path, and when upgrading the base station to multi-path Switch control alone can support the smart antenna or diversity scheme.

In addition, when the multi-path support, the output of each power amplifier can be reduced by the number of paths than the output when supporting a single path, and when using a smart antenna, the output can be reduced in proportion to the square of the number of paths, There is also an advantage that the conventional Doherty amplifier can overcome the disadvantages of output overspec inevitably in multipath support.

In addition, since the additional cost of manufacturing a Doherty amplifier using the technique according to the present invention only costs a switch, the cost may also be much lower than that of supporting a multipath with a conventional structure.

Claims (4)

A multi-input switch configured to receive a plurality of input signals and selectively switch signals in a single or multi-path by selecting necessary signals; A carrier amplifier for carrier amplifying the signal of the multiple input switch; A first 90 degree phase shifter for shifting the output of the carrier amplifier 90 degrees; Second to N-th 90 degree phase shifters which respectively phase shift the signals of the multiple input switch; First to N-th peak amplifying units configured to receive the outputs of the second to N-th 90 degree phase shifters and to respectively amplify the peaks; A multiple output switch configured to receive the outputs of the first 90 degree phase shifter and the first to N-th peak amplification sections, selectively switch the output signals switched by a single or a plurality of antennas; And a gate bias control unit configured to control the second to N-th 90 degree phase shifters such that the outputs of the first to N-1 peak amplifiers are equal to the gate biases of the carrier amplifiers. . The method of claim 1, wherein the multiple output switch, A multi-path Doherty amplifier, characterized in that for outputting a signal switched by a plurality of smart antenna, respectively. A first step of receiving a signal through a multipath and selecting a required signal and switching to a single or multipath; A second step of performing carrier amplification and peak amplification and phase-aligning the selected input switched signal after the first step; And a third step of selectively switching the amplified power after the second step into a single or multipath and outputting a signal switched by a single or a plurality of antennas, respectively. . The method of claim 3, wherein the third step, The control method of the multi-path Doherty amplifier, characterized in that for switching the amplified power in a multi-path to output to each of a plurality of smart antenna.

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