JP2014241488A - Multiband amplifier and signal amplification method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To amplify signals in a plurality of bands with high efficiency and on a small circuit scale.SOLUTION: An input end of a carrier amplifier 4a is connected to an input end of a peak amplifier 9 via a filter 8. An output end of the carrier amplifier 4a is connected to an output end of the peak amplifier 9 via a filter 10. An input end of a carrier amplifier 4b is connected to the input end of the peak amplifier 9 via a filter 11. An output end of the carrier amplifier 4b is connected to the output end of the peak amplifier 9 via a filter 12. The carrier amplifier 4a and the peak amplifier 9 constitute at least part of a Doherty amplifier 20a for amplifying a signal in a first band. The carrier amplifier 4b and the peak amplifier 9 constitute at least part of a Doherty amplifier 20b for amplifying a signal in a second band. The filters 8 and 10 pass the first band and do not pass the second band. The filters 11 and 12 pass the second band and do not pass the first band.

Description

  The present invention relates to a multiband amplifier and a signal amplification method.

  A base station of a radio communication system, for example, a radio base station of a mobile phone system transmits a signal having a large difference between average power and peak power. High power power amplifiers used in such transmitters as base stations are required to reduce power consumption. Therefore, Doherty amplifiers are widely used in order to increase the efficiency of power amplifiers. In the Doherty amplifier, the signal is divided into two by the signal distributor, one signal is always amplified by the carrier amplifier, and the other signal is amplified by the peak amplifier only when the signal exceeds a predetermined level. ing. Hereinafter, the amplifier may be referred to as AMP.

  The Doherty amplifier is disclosed in Non-Patent Document 1, for example. Patent Document 1 discloses an N-way Doherty amplifier including a plurality of stages of peak AMPs. By providing a multi-stage peak AMP, the efficiency of the Doherty amplifier is further improved.

  By the way, in recent wireless communication standards, CA (Carrier Aggregation) technology that transmits and receives one signal using a plurality of frequency bands (bands) is being studied in order to realize higher-speed wireless communication. A wireless communication system employing CA technology requires a transmitter that simultaneously transmits RF (Radio Frequency) signals of a plurality of bands.

JP-T-2006-525751

McMorrow, R.M. J. et al. Upton, D .; M.M. Maloney, P .; R. “The Microwave Doherty Amplifier”, IEEE Microwave International Symposium Digest, 1994, pp1653-1656.

  As described above, the Doherty amplifier requires two types of amplifiers, a carrier AMP and a peak AMP. Therefore, if the same number of Doherty amplifiers as the number of bands are used to realize a transmitter that simultaneously transmits signals of a plurality of bands, there is a problem that the circuit scale increases.

  The present invention has been made to solve such problems, and provides a multiband amplifier and a signal amplification method capable of amplifying signals of a plurality of bands with high efficiency and a small circuit scale. Objective.

  The multi-band amplifier according to the present invention includes a plurality of carrier amplifiers corresponding to a plurality of bands on a one-to-one basis, a plurality of input-side filters corresponding to the plurality of bands on a one-to-one basis, An output-side filter and a shared peak amplifier shared by the plurality of bands. Any one of the plurality of bands is referred to as an arbitrary band. The input terminal of the arbitrary carrier amplifier corresponding to the arbitrary band among the plurality of carrier amplifiers is connected to the input terminal of the shared peak amplifier via the arbitrary input side filter corresponding to the arbitrary band among the plurality of input side filters. Connected to. The output terminal of the arbitrary carrier amplifier is connected to the output terminal of the shared peak amplifier via an arbitrary output side filter corresponding to the arbitrary band among the plurality of output side filters. The arbitrary carrier amplifier and the shared peak amplifier constitute at least a part of a Doherty amplifier that amplifies the signal of the arbitrary band. The arbitrary input side filter and the arbitrary output side filter pass the arbitrary band and do not pass bands other than the arbitrary band among the plurality of bands.

  A multiband amplifier according to the present invention includes a first distributor that distributes a first input signal of a first band, and a bias setting so that the input terminal is connected to one output terminal of the first distributor and always operates. A first carrier amplifier, a second distributor for distributing a second input signal of a second band having a higher center frequency than the first band, and an input terminal connected to one output terminal of the second distributor. A second carrier amplifier biased so as to always operate, and an input terminal connected to the other output terminal of the first distributor and the other output terminal of the second distributor, A shared peak amplifier biased to operate when the amplitude is greater than a first set amplitude and when the amplitude of the second input signal is greater than a second set amplitude; and the output end of the first carrier amplifier and the shared Peak amplifier output A first combining point connected; an output end of the second carrier amplifier; a second combining point connected to the output end of the shared peak amplifier; and the other output end of the first distributor. An input-side low-pass filter provided between the input terminals of a peak amplifier; an input-side high-pass filter provided between the other output terminal of the second distributor and the input terminal of the shared peak amplifier; An output-side low-pass filter provided between the output terminal of the shared peak amplifier and the first synthesis point, and an output-side high-pass filter provided between the output terminal of the shared peak amplifier and the second synthesis point It comprises.

  In the signal amplification method according to the present invention, the first carrier amplifier biased so as to always operate generates the first carrier amplification signal based on the signal obtained by distributing the first input signal of the first band, and always operates. A second carrier amplifier biased to generate a second carrier amplified signal based on a signal obtained by distributing a second input signal of a second band having a higher center frequency than the first band, and the first input The other signals to which the signal is distributed are operated via the input side low-pass filter when the amplitude of the first input signal is larger than the first set amplitude and when the amplitude of the second input signal is larger than the second set amplitude. Output to the shared peak amplifier that is biased so that the other input signal is distributed to the shared peak amplifier via the input side high-pass filter. The peak amplified signal generated by the shared peak amplifier is output to an output side low pass filter and an output side high pass filter, and based on the peak amplified signal component and the first carrier amplified signal that have passed through the output side low pass filter, A first output signal is synthesized, and a second output signal is synthesized based on the component of the peak amplified signal that has passed through the output high-pass filter and the second carrier amplified signal.

  According to the present invention, it is possible to provide a multiband amplifier and a signal amplification method capable of amplifying signals of a plurality of bands with a small circuit scale with high efficiency.

1 is a schematic diagram of a multiband amplifier according to a first exemplary embodiment. FIG. 3 is a waveform diagram of an input signal of the multiband amplifier according to the first embodiment. Pass signal (a) of input-side low-pass filter according to the first embodiment, pass signal (b) of input-side high-pass filter according to the first embodiment, and input signal (c) of shared peak amplifier according to the first embodiment FIG. 6 is a graph showing the relationship between the input signal of the shared peak amplifier according to the first embodiment and the PAPR and CCDF of a normal LTE signal. The output signal (a) of the shared peak amplifier according to the first embodiment, the pass signal (b) of the output-side low-pass filter according to the first embodiment, and the pass signal (c) of the output-side high-pass filter according to the first embodiment. FIG. FIG. 3 is a schematic diagram of a multiband amplifier according to a second exemplary embodiment. 6 is a schematic diagram of a multiband amplifier according to Comparative Example 1. FIG. 6 is a schematic diagram of a multiband amplifier according to Comparative Example 2. FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
First, the multiband amplifier and the signal amplification method according to the first embodiment will be described. The multiband amplifier according to the first embodiment can be used, for example, as an apparatus including a base station amplifier of a wireless communication system, particularly a plurality of high-frequency amplifiers.

  The configuration of the multiband amplifier according to the first embodiment will be described with reference to FIG. The multiband amplifier amplifies signals in two bands of 1.7 GHz band and 2 GHz band. The multiband amplifier includes carriers AMPs 4a and 4b corresponding to two bands on a one-to-one basis, filters 8 and 11 corresponding to two bands on a one-to-one basis, filters 10 and 12 corresponding to two bands on a one-to-one basis, And a peak AMP9 shared by the two bands. The filters 8 and 11 may be referred to as input side filters 8 and 11, respectively. The filters 10 and 12 may be referred to as output side filters 10 and 12, respectively. The peak AMP9 may be referred to as a shared peak AMP9.

  The input end of the carrier AMP 4 a is connected to the input end of the peak AMP 9 through the filter 8. The input end of the carrier AMP 4 b is connected to the input end of the peak AMP 9 through the filter 11. The output end of the carrier AMP 4 a is connected to the output end of the peak AMP 9 through the filter 10. The output terminal of the carrier AMP 4 b is connected to the output terminal of the peak AMP 9 through the filter 12. The carrier AMP4a and the peak AMP9 constitute at least a part of the Doherty amplifier 20a that amplifies a 1.7 GHz band signal. The carrier AMP4b and the peak AMP9 constitute at least a part of the Doherty amplifier 20b that amplifies a signal of 2 GHz band.

  Filters 8 and 10 pass the 1.7 GHz band and do not pass the 2 GHz band. The filters 11 and 12 pass the 2 GHz band and do not pass the 1.7 GHz band.

  Since the Doherty amplifiers 20a and 20b are used for signal amplification, the multiband amplifier according to the first embodiment is highly efficient. Furthermore, since the peak AMP9 is shared by two bands, the circuit scale of the multiband amplifier according to the first embodiment is small. Therefore, the multiband amplifier according to the first embodiment can amplify signals of a plurality of bands with high efficiency and a small circuit scale.

  Furthermore, the filters 8 and 11 ensure the isolation of the two bands in the carriers AMP4a and 4b. The filter 10 prevents the 2 GHz band component included in the output signal of the peak AMP9 from being combined with the output signal of the carrier AMP4a. The filter 12 prevents the 1.7 GHz band component included in the output signal of the peak AMP9 from being combined with the output signal of the carrier AMP4b.

  The multiband amplifier according to the first embodiment preferably includes delay devices 2a and 2b corresponding to two bands on a one-to-one basis. The delay device 2a is provided in series with the carrier AMP4a and in parallel with the carrier AMP4b and the peak AMP9. The delay device 2b is provided in series with the carrier AMP4b and in parallel with the carrier AMP4a and the peak AMP9.

  The component that has passed through the filter 10 in the output signal of the peak AMP 9 is delayed by the filters 8 and 10. Of the output signal of the peak AMP 9, the component that has passed through the filter 12 is delayed by the filters 11 and 12. The delay unit 2a can match the phase of the component of the output signal of the peak AMP9 that has passed through the filter 10 and the output signal of the carrier AMP4a. The delay unit 2b can match the phase of the output signal of the peak AMP9 when the component that has passed through the filter 12 and the output signal of the carrier AMP4b are combined.

  Hereinafter, the multiband amplifier and the signal amplification method according to Embodiment 1 will be described in detail.

  With reference to FIG. 1, the configuration of the multiband amplifier according to the first exemplary embodiment will be described in detail. The multiband amplifier includes a divider 1a, a delay device 2a, a carrier AMP 4a, a λ / 4 transmission line 6a, a synthesis point 13a, a filter 8, a filter 11, a peak AMP 9, a filter 10, a filter 12, a divider 1b, a delay device 2b, A carrier AMP 4b, a λ / 4 transmission line 6b, and a synthesis point 13b are provided. Filters 8 and 10 are low-pass filters. Filters 11 and 12 are high-pass filters.

  One output terminal of the distributor 1a is connected to the input terminal of the carrier AMP 4a via the delay device 2a. The output terminal of the carrier AMP4a is connected to the synthesis point 13a via the λ / 4 transmission line 6a. One output terminal of the distributor 1b is connected to the input terminal of the carrier AMP 4b via the delay device 2b. The output terminal of the carrier AMP4b is connected to the synthesis point 13b via the λ / 4 transmission line 6b.

  The other output terminal of the distributor 1 a is connected to the input terminal of the peak AMP 9 through the filter 8. The other output terminal of the distributor 1 b is connected to the input terminal of the peak AMP 9 through the filter 11. The output terminal of the peak AMP 9 is connected to the synthesis point 13 a via the filter 10 and connected to the synthesis point 13 b via the filter 12.

  Here, it can be interpreted that the multiband amplifier according to the first exemplary embodiment includes the Doherty amplifier 20a that amplifies a 1.7 GHz band signal and the Doherty amplifier 20b that amplifies a 2 GHz band signal. The Doherty amplifiers 20a and 20b are Doherty type high power amplifiers (HPA). The peak AMP9 is shared by the Doherty amplifiers 20a and 20b. That is, the Doherty amplifier 20a includes a distributor 1a, a delay device 2a, a carrier AMP 4a, a λ / 4 transmission line 6a, a combining point 13a, a filter 8, a filter 10, and a peak AMP9. The Doherty amplifier 20b includes a distributor 1b, a delay device 2b, a carrier AMP 4b, a λ / 4 transmission line 6b, a synthesis point 13b, a filter 11, a filter 12, and a peak AMP9. The peak AMP 9 may be referred to as a duplexer (DUP: Duplexer) 9.

  The delay devices 2a and 2b may be referred to as delay circuits 2a and 2b, respectively. The λ / 4 transmission lines 6a and 6b may be referred to as quarter wavelength transmission lines 6a and 6b, respectively. Carriers AMP4a and 4b may be referred to as main AMPs 4a and 4b, respectively. The peak AMP9 may be referred to as auxiliary AMP9 or shared auxiliary AMP9. Since the filters 8 and 11 are provided on the input side of the peak AMP 9, they may be referred to as an input-side filter 8 (input-side low-pass filter 8) and an input-side filter 11 (input-side high-pass filter 11), respectively. Since the filters 10 and 12 are provided on the output side of the peak AMP 9, they may be referred to as an output side filter 10 (output side low pass filter 10) and an output side filter 12 (output side high pass filter 12), respectively.

  Next, the operation of the multiband amplifier according to the first embodiment will be described. The multiband amplifier according to the first embodiment is a multiband amplifier of a radio base station that transmits a 1.7 GHz band LTE (Long Term Evolution) signal and a 2 GHz band LTE signal. The center frequency of the 2 GHz band is higher than the center frequency of the 1.7 GHz band.

  The distributor 1a receives a 1.7 GHz band LTE transmission signal. The 1.7 GHz LTE transmission signal may be referred to as a 1.7 G input signal or a 1.7 G input. The distributor 1a distributes the 1.7G input signal into two. The distributor 1a outputs a signal obtained by distributing the 1.7G input signal to the carrier AMP 4a via the delay unit 2a, and outputs another signal obtained by distributing the 1.7G input signal to the peak AMP 9 via the filter 8. The delay device 2a delays the signal obtained by distributing the 1.7G input signal. The carrier AMP 4a generates a 1.7G carrier amplified signal based on the signal obtained by distributing the 1.7G input signal. The carrier AMP 4a outputs a 1.7G carrier amplified signal to the synthesis point 13a via the λ / 4 transmission line 6a.

  The distributor 1b inputs a 2 GHz band LTE transmission signal. The LTE transmission signal in the 2 GHz band may be referred to as a 2G input signal or a 2G input. The distributor 1b distributes the 2G input signal into two. The distributor 1b outputs a signal obtained by distributing the 2G input signal to the carrier AMP 4b via the delay unit 2b, and outputs another signal obtained by distributing the 2G input signal to the peak AMP 9 via the filter 11. The delay device 2b delays the signal obtained by distributing the 2G input signal. The carrier AMP4b generates a 2G carrier amplified signal based on the signal obtained by distributing the 2G input signal. The carrier AMP4b outputs the 2G carrier amplified signal to the synthesis point 13b via the λ / 4 transmission line 6b.

  The operating points of the carriers AMP4a and 4b are set so that the maximum efficiency is obtained at an average signal level that is about 6 dB lower than the signal peak, like the carrier AMP of a general Doherty amplifier. The output impedances of the carriers AMP4a and 4b change according to the on / off state of the peak AMP9. At a signal level at which the peak AMP 9 does not operate, the output impedance of the λ / 4 transmission line 6a is ½ of the characteristic impedance of the λ / 4 transmission line 6a, and the output impedance of the carrier AMP 4a is the characteristic impedance of the λ / 4 transmission line 6a. The output impedance of the λ / 4 transmission line 6b is ½ of the characteristic impedance of the λ / 4 transmission line 6b, and the output impedance of the carrier AMP4b is twice the characteristic impedance of the λ / 4 transmission line 6b. The carriers AMP 4a and 4b are designed to be efficient at that time.

  FIG. 2 shows the relationship between the amplitude and time of the 1.7G input signal and the 2G input signal. The operation areas 54 of the carriers AMP4a and 4b are set to the entire amplitude ranges of the 1.7G input signal and the 2G input signal, respectively. That is, the carriers AMP4a and 4b are biased so that they always operate. On the other hand, since the peak AMP9 is biased to class C, the operation region 59 of the peak AMP9 is set to an amplitude range larger than the set amplitude 49. That is, the peak AMP9 operates when the amplitude of the 1.7G input signal is larger than the set amplitude 49 and when the amplitude of the 2G input signal is larger than the set amplitude 49, whichever amplitude of the 1.7G input signal and the 2G input signal. Also, the bias is set so as not to operate when the amplitude is smaller than the set amplitude 49. Therefore, the peak AMP9 is designed to be efficient when the amplitude of the 1.7G input signal is larger than the set amplitude 49 and when the amplitude of the 2G input signal is larger than the set amplitude 49.

  Referring to FIG. 3A, the filter characteristic 68 of the filter 8 is set so as to pass the 1.7 GHz band and not pass the 2 GHz band. Therefore, the filter 8 passes other signals obtained by distributing the 1.7G input signal. Referring to FIG. 3B, the filter characteristic 71 of the filter 11 is set so as to pass the 2 GHz band and not pass the 1.7 GHz band. Therefore, the filter 11 passes other signals obtained by distributing the 2G input signal. The signal that has passed through the filter 8 and the signal that has passed through the filter 11 are combined as shown in FIG. This synthesized signal is input to the peak AMP9.

  The peak AMP 9 receives a signal that has passed through the filter 8 (another signal to which the 1.7G input signal is distributed) and a signal that has passed the filter 11 (another signal to which the 2G input signal has been distributed). When the amplitude of the 1.7G input signal is larger than the set amplitude 49 and when the amplitude of the 2G input signal is larger than the set amplitude 49, the peak AMP9 generates a peak amplified signal based on the input signal. The peak AMP 9 outputs a peak amplified signal to the filters 10 and 12. Since there is no correlation between the 1.7G input signal and the 2G input signal, the probability that the peak AMP9 operates simultaneously with signals in the 1.7G band and the 2G band is low.

  FIG. 4 shows the relationship between the input signal of the peak AMP9 and the PAPR (Peak to Average Power Ratio) and CCDF (Complementary Cumulative Distribution Function) of a normal LTE signal. Since the input signal (broken line) of the peak AMP9 is a combined signal of two bands, the probability of occurrence is slightly higher than a normal LTE signal (solid line) that is a signal of one band.

  When PAPR is 6 dB or less, the peak AMP9 does not operate, and thus the probability distribution of the input signal of the peak AMP9 is not affected. When the PAPR is 6 dB or more, the input signal of the peak AMP9 has a higher CCDF than the normal LTE signal. However, when the PAPR is 9 dB or more, since the probability of occurrence for each band is originally very low, even if signals of two bands are combined, the PAPR hardly increases. That is, although the peak AMP9 is shared by two bands, the saturation output of the peak AMP9 is sufficient to be about the same as the saturation output of the peak AMP of a general Doherty amplifier used in one band. The peak AMP9 can be used with power smaller than the combined power of two carriers.

  Referring to FIG. 5A, the peak amplified signal output from peak amplifier 9 includes a 1.7 GHz band component and a 2 GHz band component. Referring to FIG. 5B, the filter characteristic 70 of the filter 10 is set so as to pass the 1.7 GHz band and not pass the 2 GHz band. Therefore, the filter 10 passes the 1.7 GHz band component of the peak amplified signal and does not pass the 2 GHz band component. Referring to FIG. 5C, the filter characteristic 72 of the filter 12 is set so as to pass the 2 GHz band and not pass the 1.7 GHz band. Therefore, the filter 12 passes the 2 GHz band component of the peak amplified signal and does not pass the 1.7 GHz band component.

  When the amplitude of the 1.7G input signal is smaller than the set amplitude 49, the combining point 13a outputs a 1.7G carrier amplified signal that has passed through the λ / 4 transmission line 6a as a 1.7G output signal. When the amplitude of the 1.7G input signal is larger than the set amplitude 49, the combining point 13a is 1 based on the component of the peak amplified signal that has passed through the filter 10 and the 1.7G carrier amplified signal that has passed through the λ / 4 transmission line 6a. The 7G output signal is synthesized, and the synthesized 1.7G output signal is output. The 1.7G output signal may be referred to as a 1.7G output.

  When the amplitude of the 2G input signal is smaller than the set amplitude 49, the combining point 13b outputs the 2G carrier amplified signal that has passed through the λ / 4 transmission line 6b as the 2G output signal. When the amplitude of the 2G input signal is larger than the set amplitude 49, the synthesis point 13b synthesizes the 2G output signal based on the component of the peak amplified signal that has passed through the filter 10 and the 2G carrier amplified signal that has passed through the λ / 4 transmission line 6b. Then, the synthesized 2G output signal is output. The 2G output signal may be referred to as 2G output.

  Here, by designing the filters 10 and 12 so that the 2 GHz band side is totally reflected from the 1.7 GHz band side and the 1.7 GHz band side is totally reflected from the 2 GHz band side, the influence during synthesis can be reduced. .

  Hereinafter, in order to further clarify the effects of the multiband amplifier and the signal amplification method according to the present embodiment, the multiband amplifier according to the present embodiment is compared with the multiband amplifier according to the comparative example.

(Comparative Example 1)
A multiband amplifier according to Comparative Example 1 will be described with reference to FIG. The multiband amplifier according to Comparative Example 1 includes two systems of Doherty amplifiers 120a and 120b in order to amplify signals of two bands. The Doherty amplifier 120a amplifies a 1.7 GHz band signal. The Doherty amplifier 120b amplifies a 2 GHz band signal.

  The Doherty amplifier 120a includes a distributor 103a, a carrier AMP 104a, a λ / 4 transmission line 106a, a combining point 113a, and a peak AMP 105a. One output terminal of the distributor 103a is connected to the input terminal of the carrier AMP 104a. The output terminal of the carrier AMP 104a is connected to the synthesis point 113a via the λ / 4 transmission line 106a. The other output terminal of the distributor 103a is connected to the input terminal of the peak AMP 105a. The output end of the peak AMP 105a is connected to the synthesis point 113a.

  The distributor 103a receives the 1.7G input signal and distributes it into two. The carrier AMP 104a always amplifies the signal obtained by distributing the 1.7G input signal to generate a carrier amplified signal. The carrier AMP 104a outputs the carrier amplified signal to the synthesis point 113a via the λ / 4 transmission line 106a. When the amplitude of the 1.7G input signal is larger than the set amplitude, the peak AMP 105a amplifies other signals to which the 1.7G input signal is distributed to generate a peak amplified signal, and outputs the peak amplified signal to the synthesis point 113a. . When the amplitude of the 1.7G input signal is smaller than the set amplitude, the combining point 113a outputs the carrier amplified signal that has passed through the λ / 4 transmission line 106a as a 1.7G output signal. When the peak AMP 105a is operating, the synthesis point 113a synthesizes the 1.7G output signal based on the carrier amplified signal and the peak amplified signal that have passed through the λ / 4 transmission line 106a, and outputs the synthesized 1.7G output signal. To do.

  The Doherty amplifier 120b includes a distributor 103b, a carrier AMP 104b, a λ / 4 transmission line 106b, a combining point 113b, and a peak AMP 105b. The connection relation and operation of the elements of the Doherty amplifier 120b are the same as the connection relation and operation of the elements of the Doherty amplifier 120a. However, the Doherty amplifier 120b receives a 2G input signal and outputs a 2G output signal.

(Comparison between Comparative Example 1 and Embodiment 1)
In the multiband amplifier according to the first comparative example, the Doherty amplifier 120a that amplifies the 1.7 GHz band signal includes the peak AMP 105a, and the Doherty amplifier 120b that amplifies the 2 GHz band signal includes the peak AMP 105b. That is, carrier AMPs 104a and 14b are provided for each band, and peaks AMPs 105a and 105b are provided for each band. Although the peak AMPs 5a and 5b require a device size that matches the maximum amplitude of the input signal, they operate only when the amplitude of the input signal is large, so that the time availability is low.

  On the other hand, in the multiband amplifier according to the first embodiment, the Doherty amplifier 20a that amplifies the 1.7 GHz band signal and the Doherty amplifier 20b that amplifies the 2 GHz band signal share the peak AMP9. That is, the carriers AMP4a and 4b are provided for each band, but the peak AMP9 is shared by the two bands. Since only one peak AMP is required, the circuit scale of the multiband amplifier according to the first embodiment can be reduced, and the cost can be reduced. Furthermore, since the peak AMP9 is shared by the two bands, the time availability of the peak AMP9 is increased.

(Comparative Example 2)
With reference to FIG. 8, the multiband amplifier concerning the comparative example 2 is demonstrated. The multiband amplifier according to Comparative Example 2 is configured to amplify signals of two bands using one system of Doherty amplifier 220. The Doherty amplifier 220 amplifies the 1.7 GHz band signal and the 2 GHz band signal.

  The Doherty amplifier 220 includes a low-pass filter 208, a high-pass filter 211, a distributor 203, a carrier AMP 204, a peak AMP 205, a λ / 4 transmission line 206, a synthesis point 213, a low-pass filter 210, and a high-pass filter 212. Low-pass filters 208 and 210 pass the 1.7 GHz band and do not pass the 2 GHz band. The high-pass filters 211 and 212 pass the 2 GHz band and do not pass the 1.7 GHz band.

  The input end of the distributor 203 is connected to the output end of the low pass filter 208 and the output end of the high pass filter 211. One output terminal of the distributor 203 is connected to the input terminal of the carrier AMP 204. The output terminal of the carrier AMP 204 is connected to the synthesis point 213 via the λ / 4 transmission line 206. The other output terminal of the distributor 203 is connected to the input terminal of the peak AMP 205. The output terminal of the peak AMP 205 is connected to the synthesis point 213. The synthesis point 213 is connected to the input end of the low pass filter 210 and the input end of the high pass filter 212.

  The distributor 203 receives a combined signal of the 1.7 G input signal that has passed through the low pass filter 208 and the 2 G input signal that has passed through the high pass filter 211. The distributor 203 distributes the combined signal into two. The carrier AMP 204 always amplifies the signal obtained by distributing the combined signal to generate a carrier amplified signal. The carrier AMP 204 outputs the carrier amplified signal to the synthesis point 213 via the λ / 4 transmission line 206. When the amplitude of the 1.7G input signal or the 2G input signal is larger than the set amplitude, the peak AMP 205 amplifies other signals to which the synthesized signal is distributed to generate a peak amplified signal, and outputs the peak amplified signal to the synthesis point 213 To do.

  When both of the 1.7 G input signal and the 2 G input signal are smaller than the set amplitude, the synthesis point 213 outputs the carrier amplified signal that has passed through the λ / 4 transmission line 206 to the low pass filter 210 and the high pass filter 212 as an output signal. . When the amplitude of the 1.7G input signal or the 2G input signal is larger than the set amplitude, the combining point 213 combines the output signal based on the carrier amplified signal and the peak amplified signal that have passed through the λ / 4 transmission line 206, and combined output The signal is output to the low pass filter 210 and the high pass filter 212. The low pass filter 210 outputs a 1.7 GHz band component of the output signal of the synthesis point 213 as a 1.7 G output signal. The high pass filter 212 outputs a 2 GHz band component of the output signal of the synthesis point 213 as a 2G output signal.

(Comparison between Comparative Example 2 and Embodiment 1)
In the multiband amplifier according to the comparative example 2, the distributor 203, the carrier AMP 204, the peak AMP 205, the λ / 4 transmission line 206, and the synthesis point 213 are shared by two bands. However, since the λ / 4 transmission line 206 has high frequency dependence, it is difficult to increase the bandwidth. Further, when one system is compatible with multiband, the signal level is doubled, so that it is necessary to select a device having a saturated output that is twice as AMP, resulting in a large amplifier.

  On the other hand, in the multiband amplifier according to the first embodiment, only the peak AMP9 needs to be widened, and it is not necessary to widen the λ / 4 transmission lines 6a and 6b. Therefore, it is relatively easy to realize the multiband amplifier according to the first embodiment.

(Embodiment 2)
Next, a multiband amplifier and a signal amplification method according to the second embodiment will be described. In the following, description of matters common to the first embodiment may be omitted.

  The configuration of the multiband amplifier according to the second embodiment will be described with reference to FIG. The multiband amplifier amplifies signals in two bands of 1.7 GHz band and 2 GHz band. The multiband amplifier includes carriers AMPs 4a and 4b corresponding to two bands on a one-to-one basis, filters 8 and 11 corresponding to two bands on a one-to-one basis, filters 10 and 12 corresponding to two bands on a one-to-one basis, A peak AMP9 shared by the two bands and peaks AMP5a and 5b corresponding to the two bands on a one-to-one basis are provided.

  The carrier AMP4a, the peak AMP5a, and the peak AMP9 constitute at least a part of an N-way Doherty amplifier 30a that amplifies a 1.7 GHz band signal. The carrier AMP4b, the peak AMP5b, and the peak AMP9 constitute at least a part of an N-way Doherty amplifier 30b that amplifies a signal of 2 GHz band.

  In the multiband amplifier according to the second exemplary embodiment, each of the Doherty amplifiers 30a and 30b is provided with a two-stage peak AMP. Peaks AMP5a and 5b, which are first-stage peak AMPs, are provided corresponding to the 1.7 GHz band and the 2 GHz band, respectively. The peak AMP9 that is the second-stage peak AMP is shared by the two bands. That is, the peak AMP9 which is the peak AMP in the upper stage than the peaks AMP5a and 5b is shared by the two bands.

  Hereinafter, the multiband amplifier and the signal amplification method according to the second embodiment will be described in detail.

  The configuration of the multiband amplifier according to the second embodiment will be described in detail with reference to FIG. The multiband amplifier includes a distributor 1a, a delay device 2a, a distributor 3a, a carrier AMP 4a, a peak AMP 5a, a λ / 4 transmission line 7a, a combining point 14a, a λ / 4 transmission line 6a, a combining point 13a, a filter 8, and a filter 11. , Peak AMP9, filter 10, filter 12, divider 1b, delay device 2b, divider 3b, carrier AMP4b, peak AMP5b, λ / 4 transmission line 7b, synthesis point 14b, λ / 4 transmission line 6b, synthesis point 13b Prepare.

  One output terminal of the distributor 1a is connected to the input terminal of the distributor 3a via the delay device 2a. One output terminal of the distributor 3a is connected to the input terminal of the carrier AMP4a. The output end of the carrier AMP 4a is connected to the synthesis point 14a via the λ / 4 transmission line 7a. The synthesis point 14a is connected to the synthesis point 13a via the λ / 4 transmission line 6a. The other output terminal of the distributor 3a is connected to the input terminal of the peak AMP 5a. The output end of the peak AMP 5a is connected to the synthesis point 14a.

  One output terminal of the distributor 1b is connected to the input terminal of the distributor 3b via the delay device 2b. One output terminal of the distributor 3b is connected to the input terminal of the carrier AMP4b. The output terminal of the carrier AMP4b is connected to the synthesis point 14b via the λ / 4 transmission line 7b. The synthesis point 14b is connected to the synthesis point 13b via the λ / 4 transmission line 6b. The other output terminal of the distributor 3b is connected to the input terminal of the peak AMP 5b. The output terminal of the peak AMP 5b is connected to the synthesis point 14b.

  The other output terminal of the distributor 1 a is connected to the input terminal of the peak AMP 9 through the filter 8. The other output terminal of the distributor 1 b is connected to the input terminal of the peak AMP 9 through the filter 11. The output terminal of the peak AMP 9 is connected to the synthesis point 13 a via the filter 10 and connected to the synthesis point 13 b via the filter 12.

  Here, the multiband amplifier according to the second embodiment can be interpreted as including a Doherty amplifier 30a that amplifies a 1.7 GHz band signal and a Doherty amplifier 30b that amplifies a 2 GHz band signal. The Doherty amplifiers 30a and 30b are Doherty-type high power amplifiers having two-stage peak AMPs. The peak AMP9 is shared by the Doherty amplifiers 30a and 30b. That is, the Doherty amplifier 30a includes a distributor 1a, a delay device 2a, a distributor 3a, a carrier AMP 4a, a peak AMP 5a, a λ / 4 transmission line 6a, a λ / 4 transmission line 7a, a combining point 13a, a combining point 14a, a filter 8, A filter 10 and a peak AMP9 are provided. The Doherty amplifier 30b includes a distributor 1b, a delay device 2b, a distributor 3b, a carrier AMP 4b, a peak AMP 5b, a λ / 4 transmission line 6b, a λ / 4 transmission line 7b, a combining point 13b, a combining point 14b, a filter 11, and a filter 12. , Peak AMP9.

  The carriers AMP4a and 4b are biased so as to always operate. The peak AMP9 operates when the amplitude of the 1.7G input signal is larger than the set amplitude 49 and when the amplitude of the 2G input signal is larger than the set amplitude 49, and both the amplitudes of the 1.7G input signal and the 2G input signal are set. The bias is set so as not to operate when the amplitude is smaller than 49. The peak AMP 5a operates when the amplitude of the 1.7G input signal is larger than the 1.7G side set amplitude smaller than the set amplitude 49, and does not operate when the amplitude of the 1.7G input signal is smaller than the 1.7G side set amplitude. As shown, the bias is set. The peak AMP 5b is biased so that it operates when the amplitude of the 2G input signal is larger than the 2G side set amplitude smaller than the set amplitude 49, and does not operate when the amplitude of the 2G input signal is smaller than the 2G side set amplitude. .

  The λ / 4 transmission lines 7a and 7b may be referred to as quarter wavelength transmission lines 7a and 7b, respectively. Peaks AMP5a and 5b may be referred to as auxiliary AMPs 5a and 5b, respectively.

  Next, the operation of the multiband amplifier according to the second exemplary embodiment will be described. The multiband amplifier according to the second exemplary embodiment is a multiband amplifier of a radio base station that transmits a 1.7 GHz band LTE signal and a 2 GHz band LTE signal.

  The distributor 1a distributes the 1.7G input signal into two. The distributor 1a outputs a signal obtained by distributing the 1.7G input signal (hereinafter referred to as a 1.7G distributed signal) to the distributor 3a via the delay unit 2a, and outputs another signal obtained by distributing the 1.7G input signal. Output to the peak AMP 9 via the filter 8. The delay device 2a delays the 1.7G distribution signal. The distributor 3a distributes the 1.7G distribution signal into two. The distributor 3a outputs a signal obtained by distributing the 1.7G distribution signal to the carrier AMP 4a, and outputs another signal obtained by distributing the 1.7G distribution signal to the peak AMP 5a.

  The carrier AMP 4a generates a 1.7G carrier amplification signal based on the signal obtained by distributing the 1.7G distribution signal. The carrier AMP 4a outputs a 1.7G carrier amplified signal to the synthesis point 14a via the λ / 4 transmission line 7a. When the amplitude of the 1.7G input signal is larger than the 1.7G side set amplitude, the peak AMP 5a generates a 1.7G peak amplified signal based on the other signal obtained by distributing the 1.7G distribution signal, and the 1.7G peak. The amplified signal is output to the synthesis point 14a.

  When the amplitude of the 1.7G input signal is smaller than the 1.7G side set amplitude, the synthesis point 14a outputs the 1.7G carrier amplified signal that has passed through the λ / 4 transmission line 7a as the 1.7G intermediate signal. When the amplitude of the 1.7 G input signal is larger than the 1.7 G side set amplitude, the synthesis point 14 a is 1. based on the 1.7 G carrier amplified signal and the 1.7 G peak amplified signal that have passed through the λ / 4 transmission line 7 a. The 7G intermediate signal is synthesized, and the synthesized 1.7G intermediate signal is output. The synthesis point 14a outputs the 1.7G intermediate signal to the synthesis point 13a via the λ / 4 transmission line 6a.

  The distributor 1b distributes the 2G input signal into two. The distributor 1b outputs a signal obtained by distributing the 2G input signal (hereinafter referred to as a 2G distributed signal) to the distributor 3b via the delay device 2b, and peaks other signals obtained by distributing the 2G input signal via the filter 11. Output to AMP9. The delay device 2b delays the 2G distribution signal. The distributor 3b distributes the 2G distribution signal into two. The distributor 3b outputs a signal obtained by distributing the 2G distribution signal to the carrier AMP4b, and outputs another signal obtained by distributing the 2G distribution signal to the peak AMP5b.

  The carrier AMP4b generates a 2G carrier amplification signal based on the signal obtained by distributing the 2G distribution signal. The carrier AMP 4b outputs the 2G carrier amplified signal to the synthesis point 14b via the λ / 4 transmission line 7b. When the amplitude of the 2G input signal is larger than the set amplitude on the 2G side, the peak AMP 5b generates a 2G peak amplified signal based on the other signal to which the 2G distributed signal is distributed, and outputs the 2G peak amplified signal to the synthesis point 14b.

  When the amplitude of the 2G input signal is smaller than the 2G side set amplitude, the synthesis point 14b outputs the 2G carrier amplified signal that has passed through the λ / 4 transmission line 7b as the 2G intermediate signal. When the amplitude of the 2G input signal is larger than the setting amplitude on the 2G side, the combining point 14b combines the 2G intermediate signal based on the 2G carrier amplified signal and the 2G peak amplified signal that have passed through the λ / 4 transmission line 7b, and combined 2G Output intermediate signal. The synthesis point 14b outputs the 2G intermediate signal to the synthesis point 13a via the λ / 4 transmission line 6b.

  The peak AMP 9 receives a signal that has passed through the filter 8 (another signal to which the 1.7G input signal is distributed) and a signal that has passed the filter 11 (another signal to which the 2G input signal has been distributed). When the amplitude of the 1.7G input signal is larger than the set amplitude 49 and when the amplitude of the 2G input signal is larger than the set amplitude 49, the peak AMP9 generates a peak amplified signal based on the input signal. The peak AMP 9 outputs a peak amplified signal to the filters 10 and 12. The filter 10 passes the 1.7 GHz band component of the peak amplified signal and does not pass the 2 GHz band component. The filter 12 passes the 2 GHz band component of the peak amplified signal and does not pass the 1.7 GHz band component.

  When the amplitude of the 1.7G input signal is smaller than the set amplitude 49, the synthesis point 13a outputs a 1.7G intermediate signal that has passed through the λ / 4 transmission line 6a as a 1.7G output signal. When the amplitude of the 1.7G input signal is larger than the set amplitude 49, the synthesis point 13a is 1. based on the component of the peak amplified signal that has passed through the filter 10 and the 1.7G intermediate signal that has passed through the λ / 4 transmission line 6a. The 7G output signal is synthesized, and the synthesized 1.7G output signal is output.

  When the amplitude of the 2G input signal is smaller than the set amplitude 49, the synthesis point 13b outputs the 2G intermediate signal that has passed through the λ / 4 transmission line 6b as the 2G output signal. When the amplitude of the 2G input signal is larger than the set amplitude 49, the synthesis point 13b synthesizes the 2G output signal based on the peak amplified signal component that has passed through the filter 12 and the 2G intermediate signal that has passed through the λ / 4 transmission line 6b. The synthesized 2G output signal is output.

  When the two-stage peak AMP is provided in each of the Doherty amplifiers 120a and 120b included in the multiband amplifier according to the comparative example 1, the circuit scale becomes very large. In addition, the first-stage peak AMP is biased so as to operate when the amplitude of the input signal of the Doherty amplifier is larger than the first set amplitude, and the amplitude of the input signal of the Doherty amplifier is larger than the first set amplitude. The second stage peak AMP is biased so as to operate when it is larger than the second set amplitude. Therefore, the time availability of the second stage peak AMP is lower than the time availability of the first stage peak AMP.

  According to the second embodiment, since the peak AMP9 that is the second-stage peak AMP is shared by the two bands, the circuit scale of the multiband amplifier according to the second embodiment is reduced, and the second-stage peak AMP is reduced. The hourly utilization rate increases. It is effective to share the upper level peak AMP among a plurality of bands.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, the multiband amplifier and the signal amplification method according to the present invention may be a multiband amplifier and a signal amplification method for amplifying signals of three or more bands. A multiband amplifier that amplifies signals of two bands may be referred to as a dual band amplifier. The multiband amplifier and signal amplification method according to the present invention may be a multiband amplifier and signal amplification method provided with N stages (N is an integer of 3 or more) of peak AMPs. In this case, it is preferable that the N-th peak AMP is shared by a plurality of bands.

  In the above embodiment, the peak AMP 9 is biased so as to operate when the amplitude of the 1.7 G input signal is larger than the set amplitude 49 and when the amplitude of the 2 G input signal is larger than the set amplitude 49. The set amplitude for the 7G input signal and the set amplitude for the 2G input signal are the same. The set amplitude for the 1.7G input signal may be different from the set amplitude for the 2G input signal.

1a, 1b, 3a, 3b Distributor 2a, 2b Delay device (delay circuit)
4a, 4b Carrier amplifier (carrier AMP)
8, 10, 11, 12 Filters 5a, 5b, 9 Peak amplifier (peak AMP)
13a, 13b, 14a, 14b Composite points 20a, 20b, 30a, 30b Doherty amplifier 49 Setting amplitude

Claims (9)

A plurality of carrier amplifiers corresponding one-to-one to a plurality of bands;
A plurality of input side filters corresponding one-to-one to the plurality of bands;
A plurality of output-side filters corresponding one-to-one to the plurality of bands;
A shared peak amplifier shared by the plurality of bands,
Any one of the plurality of bands is referred to as an arbitrary band,
The input terminal of the arbitrary carrier amplifier corresponding to the arbitrary band among the plurality of carrier amplifiers is connected to the input terminal of the shared peak amplifier via the arbitrary input side filter corresponding to the arbitrary band among the plurality of input side filters. Connected to
An output terminal of the arbitrary carrier amplifier is connected to an output terminal of the shared peak amplifier via an arbitrary output side filter corresponding to the arbitrary band among the plurality of output side filters,
The arbitrary carrier amplifier and the shared peak amplifier constitute at least part of a Doherty amplifier that amplifies the signal of the arbitrary band,
The arbitrary input side filter and the arbitrary output side filter are multiband amplifiers that pass the arbitrary band and do not pass bands other than the arbitrary band among the plurality of bands. A plurality of delay circuits corresponding one-to-one to the plurality of bands;
An arbitrary delay circuit corresponding to the arbitrary band among the plurality of delay circuits is connected in series to the arbitrary carrier amplifier, and a carrier amplifier other than the arbitrary carrier amplifier and the shared peak amplifier among the plurality of carrier amplifiers. The multiband amplifier according to claim 1, wherein the multiband amplifier is provided in parallel. A plurality of peak amplifiers corresponding one-to-one with the plurality of bands;
The arbitrary carrier amplifier, the arbitrary peak amplifier corresponding to the arbitrary band among the plurality of peak amplifiers, and the shared peak amplifier constitute at least a part of an N-way Doherty amplifier that amplifies the signal of the arbitrary band. ,
3. The multiband amplifier according to claim 1, wherein in the N-way Doherty amplifier that amplifies the signal of the arbitrary band, the shared peak amplifier is a peak amplifier at a higher stage than the arbitrary peak amplifier. 4. A first distributor for distributing the first input signal of the first band;
A first carrier amplifier having an input terminal connected to one output terminal of the first distributor and biased so as to always operate;
A second distributor for distributing a second input signal of a second band having a higher center frequency than the first band;
A second carrier amplifier having an input terminal connected to one output terminal of the second distributor and biased so as to always operate;
The input terminal is connected to the other output terminal of the first distributor and the other output terminal of the second distributor, and when the amplitude of the first input signal is larger than the first set amplitude and the second input signal A shared peak amplifier biased to operate when the amplitude is greater than the second set amplitude;
A first combining point connected to an output terminal of the first carrier amplifier and an output terminal of the shared peak amplifier;
A second combining point connected to the output end of the second carrier amplifier and the output end of the shared peak amplifier;
An input-side low-pass filter provided between the other output terminal of the first distributor and the input terminal of the shared peak amplifier;
An input-side high-pass filter provided between the other output terminal of the second distributor and the input terminal of the shared peak amplifier;
An output-side low-pass filter provided between the output terminal of the shared peak amplifier and the first synthesis point;
A multiband amplifier comprising: an output-side high-pass filter provided between the output terminal of the shared peak amplifier and the second synthesis point. A first delay circuit provided between the one output terminal of the first distributor and the input terminal of the first carrier amplifier;
The multiband amplifier according to claim 4, further comprising a second delay circuit provided between the one output terminal of the second distributor and the input terminal of the second carrier amplifier. A third distributor having an input terminal connected to the one output terminal of the first distributor and one output terminal connected to the input terminal of the first carrier amplifier;
The input terminal is connected to the other output terminal of the third distributor, the output terminal is connected to the first synthesis point, and the amplitude of the first input signal is larger than the third set amplitude smaller than the first set amplitude. A first peak amplifier biased to operate in case
A fourth distributor having an input terminal connected to the one output terminal of the second distributor and one output terminal connected to the input terminal of the second carrier amplifier;
The input terminal is connected to the other output terminal of the fourth distributor, the output terminal is connected to the second synthesis point, and the amplitude of the second input signal is larger than the fourth set amplitude smaller than the second set amplitude. The multiband amplifier according to claim 4, further comprising a second peak amplifier biased to operate in some cases. A first carrier amplifier biased to operate constantly generates a first carrier amplified signal based on a signal obtained by distributing the first input signal of the first band;
A second carrier amplifier biased so as to always operate generates a second carrier amplified signal based on a signal obtained by distributing a second input signal of a second band having a higher center frequency than the first band;
The other signals to which the first input signal is distributed are passed through an input-side low-pass filter when the amplitude of the first input signal is greater than the first set amplitude and the amplitude of the second input signal is greater than the second set amplitude. Output to a shared peak amplifier that is biased to work when large,
The other signal obtained by distributing the second input signal is output to the shared peak amplifier via an input side high-pass filter,
The peak amplification signal generated by the shared peak amplifier is output to the output side low pass filter and the output side high pass filter,
Based on the component of the peak amplified signal that has passed through the output-side low pass filter and the first carrier amplified signal, a first output signal is synthesized,
A signal amplification method for synthesizing a second output signal based on the component of the peak amplified signal that has passed through the output high-pass filter and the second carrier amplified signal. Delaying the signal to which the first input signal has been distributed;
The signal amplification method according to claim 7, wherein the signal obtained by distributing the second input signal is delayed. A signal obtained by distributing the signal obtained by distributing the first input signal is output to the first carrier amplifier;
A first peak amplifier biased to operate when the amplitude of the first input signal is greater than a third set amplitude that is less than the first set amplitude distributed the signal that has distributed the first input signal Generating a first peak amplified signal based on other signals;
A signal obtained by distributing the signal obtained by distributing the second input signal is output to the second carrier amplifier;
A second peak amplifier biased to operate when the amplitude of the second input signal is greater than a fourth set amplitude that is less than the second set amplitude distributed the signal from which the second input signal was distributed Generating a second peak amplified signal based on other signals;
The first output signal is further synthesized based on the first peak amplified signal;
The signal amplification method according to claim 7, wherein the second output signal is further synthesized based on the second peak amplification signal.

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