JP2005073061A - Gain control method, gain control circuit, radio transmitter, radio receiver, and radio measurement equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gain control circuit and a gain control method using the same, etc. with a simple circuit configuration, having a smooth phase variation produced in an input signal when adjusting the gain, and a small phase variation amount thereof. <P>SOLUTION: A controller 116 obtains and retains respective characteristics of an ATT 112a through an ATT 112m in regard to the phase variation amount against an input signal attenuation amount; and calculates the combination of the input signal attenuation amount of the ATT 112a through the ATT 112m, which makes the least phase variation amount generated in the input signal when adjusting the gain of the gain control circuit 100, using an arithmetic circuit based on the characteristics. The controller 116 then inputs a set signal 115a through a set signal 115m to the ATT 112a to the ATT 112m, respectively, according to the combination of the calculated input signal attenuation amount. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a gain control method, a gain control circuit, and a radio transmission apparatus, radio reception apparatus, and radio measurement apparatus using the circuit.

  Conventionally, an automatic gain control circuit that keeps the gain and phase between the input and output of the automatic gain control circuit constant is known (see, for example, Patent Document 1).

FIG. 5 is a block diagram showing the configuration of the gain control circuit described in Patent Document 1. In FIG. The conventional gain control circuit includes a directional coupler 52 a that outputs the input signal 10 from the input terminal 51 to the level adjuster 53 and distributes it to the delay line 59, and a control signal 60 from the control circuit 56. And a directional coupling that distributes the signal amplified by the amplifier 54 to the output signal 70 to the output terminal 57 and the signal to the synthesizer 61. 52b. This conventional gain control circuit attenuates the amplified output of the amplifier 54 with the same attenuation factor as the amplification factor, and the level adjuster 53 and the phase adjuster so that the level difference between the attenuated output and the input signal becomes zero. The level and phase of the signal are kept constant by alternately controlling the signal 58 and the signal 58.
Japanese Patent Laid-Open No. 9-64673 (page 4, FIG. 1)

  However, the gain control circuit described in Patent Document 1 has a problem that the number of parts is large and the circuit configuration becomes complicated.

  The present invention has been made in view of the above points, and has a simple circuit configuration, a phase change that occurs in an input signal when a gain is changed, and a gain control circuit having a small amount of phase change. An object of the present invention is to provide a gain control method using this circuit.

  The gain control method according to the present invention includes an acquisition step of acquiring characteristics of each of a plurality of digitally controlled attenuators connected in series with respect to a phase change amount with respect to an attenuation amount of an input signal, and an input signal according to the acquired characteristics. A setting step for setting the attenuation amount of each input signal of the digital control attenuator in a range where the phase change amount with respect to the attenuation amount is flat; an attenuation step for attenuating the input signal by the attenuation amount set by the digital control attenuator; It was made to comprise.

  According to this method, the attenuation amount of the input signal of each digital control attenuator is set according to the characteristics of each of the plurality of digital control attenuators. Therefore, the attenuation of the input signal in the entire plurality of digital control attenuators connected in series. The phase change amount with respect to the amount can be smoothly changed, and the phase change amount generated in the input signal can be reduced.

  According to the phase control method of the present invention, in the above invention, in the setting step, the phase change amount of the input signal in all of the plurality of digital control attenuators connected in series according to the acquired characteristics is the minimum. A combination of attenuation amounts of the input signals of the digital control attenuators is calculated, and an attenuation amount of the input signals of the digital control attenuators is set according to the calculated combination.

  According to this method, in addition to the effects of the present invention, the attenuation amount of the input signal of each digital control attenuator is set so that the amount of phase change of the input signal in the entire plurality of digital control attenuators connected in series is minimized. Therefore, it is possible to reduce the risk of an error when an input signal attenuated by a plurality of digital control attenuators is output.

  A gain control circuit according to the present invention includes a plurality of serially connected digital control attenuators for attenuating an input signal by a set attenuation amount, and characteristics of the digital control attenuator with respect to a phase change amount with respect to the attenuation amount of the input signal. And a control means for setting the attenuation amount of each input signal of the digital control attenuator in a range where the phase change amount with respect to the attenuation amount of the input signal is flat.

  According to this configuration, since the attenuation amount of the input signal of each digital control attenuator is set according to the characteristics of each of the plurality of digital control attenuators, the attenuation of the input signal in the entire plurality of digital control attenuators connected in series. The phase change amount with respect to the amount can be smoothly changed, and the phase change amount generated in the input signal can be reduced. Further, according to this configuration, it is only necessary to connect the digital control attenuators in series, so that the configuration of the gain control circuit can be simplified.

  The gain control circuit according to the present invention employs a configuration including an amplifier that amplifies the input signal attenuated by the digital control attenuator in the invention.

  According to this configuration, in addition to the effect of the present invention, the input signal attenuated by the digital control attenuator is amplified by the amplifier, so that the dynamic range of the gain control circuit can be improved.

  A radio transmission apparatus according to the present invention employs a configuration including the gain control circuit according to claim 3.

  According to this configuration, since the gain control circuit according to the invention is provided, the circuit configuration can be simplified and the manufacturing cost can be reduced, and the amount of phase change generated in the input signal when the gain is adjusted can be reduced. Can be small.

  A radio receiving apparatus according to the present invention employs a configuration including the gain control circuit according to claim 3.

  According to this configuration, since the gain control circuit according to the invention is provided, the circuit configuration can be simplified and the manufacturing cost can be reduced, and the amount of phase change generated in the input signal when the gain is adjusted can be reduced. Can be small.

  A radio measurement apparatus according to the present invention employs a configuration including the gain control circuit according to claim 3.

  According to this configuration, since the gain control circuit according to the invention is provided, the circuit configuration can be simplified and the manufacturing cost can be reduced, and the amount of phase change generated in the input signal when the gain is adjusted can be reduced. Can be small. Further, according to this configuration, even if the gain is adjusted, the amount of phase change that occurs in the input signal is small, so that the direction in which the radio signal is transmitted can be accurately measured by applying it to an array antenna or the like. .

  According to the present invention, since the attenuation amount of the input signal of each digital control attenuator is set in accordance with the characteristics of each of the plurality of digital control attenuators, the attenuation of the input signal in the entire plurality of digital control attenuators connected in series. The phase change amount with respect to the amount can be smoothly changed, and the phase change amount generated in the input signal can be reduced. Further, according to the present invention, since it is only necessary to connect the digital control attenuators in series, the configuration of the gain control circuit can be simplified.

  The essence of the present invention is that, in a gain control circuit in which a plurality of digital control attenuators are connected in series, each characteristic of the digital control attenuator with respect to the phase change amount with respect to the attenuation amount of the input signal is acquired, and according to the acquired characteristic The attenuation amount of the digital control attenuator is set in a range where the phase change amount with respect to the attenuation amount of the input signal is flat.

  Hereinafter, a gain control circuit according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of a gain control circuit 100 according to the present embodiment. The gain control circuit 100 includes a plurality of digital control attenuators (hereinafter referred to as “ATT”) 112, a plurality of amplifiers 113, and a control unit 116.

  The ATT 112 attenuates the input signal input from the input terminal 111 by the set attenuation amount in accordance with the setting signal 115 input from the control unit 116. The ATT 112 is comprehensively expressed as ATT 112 when not distinguishing each ATT, and is further denoted as ATTs 112a, 112b,. Further, the setting signal 115 is also described with an identification code corresponding to each of the ATT 112a to ATT 112m as necessary.

  The amplifier 113 is composed of a general-purpose transistor or the like, and amplifies the input signal attenuated by the ATT 112 with a predetermined amplification factor. Since the amplifier 113 is arranged behind in the flow direction of the input signal of the ATT 112, the dynamic range of the gain control circuit 100 is improved. In addition, the amplifier 113 is comprehensively expressed as an amplifier 113 when the amplifiers are not distinguished from each other, and is further denoted by amplifiers 113a, 113b,. To do.

  The control unit 116 includes a general-purpose memory, an arithmetic circuit, and the like, and acquires and holds the characteristics of the ATT 112a to ATT 112m regarding the phase change amount with respect to the attenuation amount of the input signal. Further, the control unit 116, based on the above characteristics, sets the combinations of the attenuation values of the input signals of the ATT 112a to ATT 112m that minimize the amount of phase change that occurs in the input signal when the gain of the gain control circuit 100 is adjusted. Is calculated by an arithmetic circuit. Then, the control unit 116 inputs the setting signal 115a to the setting signal 115m to the ATT 112a to the ATT 112m according to the calculated combination of setting values.

  FIG. 2 shows an example of the phase change amount with respect to the attenuation amount of the input signal in the ATT 112. The graph shown in FIG. 2 is obtained by actually measuring the phase change amount of the input signal when the set value of the attenuation amount is increased by 0.5 dB in any ATT 112. In general, in the ATT 112, the phase of the input signal is delayed because the electrical length increases as the attenuation of the input signal increases. However, the phase change amount of the input signal in the ATT 112 does not always increase in proportion to the attenuation amount. For example, the range in which the input signal attenuation amount increases rapidly as in the range A from 31 dB to 32 dB in FIG. Exists. Therefore, when adjusting the gain of the gain control circuit 100, if the attenuation amount of an arbitrary ATT 112 is set before and after the range A, the continuity of the phase change amount with respect to the attenuation amount of the input signal in the gain control circuit 100 is increased. It will be damaged. Such a lack of continuity of the phase change amount with respect to the attenuation amount of the input signal increases a risk that the output signal from the gain control circuit 100 becomes an error. Further, when the gain in the gain control circuit 100 is adjusted frequently or rapidly, even if the continuity of the phase change amount with respect to the attenuation amount of the input signal is maintained, the phase change amount of the input signal increases. The risk that the output signal from the gain control circuit 100 becomes an error increases. Therefore, in the gain control circuit 100, from the ATT 112a, the continuity of the phase change amount with respect to the attenuation amount of the input signal is maintained, and the phase change amount is reduced even if the attenuation amount of the input signal is large. It is necessary to set a combination of attenuation amounts of the input signals in accordance with the characteristics of the ATT 112m. Note that the phase change amount with respect to the amplification amount of the input signal in the amplifier 113 is sufficiently flat compared with the phase change amount with respect to the attenuation amount of the input signal in the ATT 112, and therefore, when adjusting the gain in the gain control circuit 100, Only the characteristics of the ATT 112 need be considered.

  Here, it is assumed that all of the plurality of ATTs 112 included in the gain control circuit 100 have the characteristics shown in FIG. 2 with respect to the phase change amount with respect to the attenuation amount of the input signal. In the gain control circuit 100, in order that the phase change amount with respect to the attenuation amount of the input signal has continuity and the phase change amount becomes small even when the input signal attenuation amount is large, each input signal of the ATT 112 Must be set in a range where the amount of phase change with respect to the attenuation is flat, that is, in a range B from 0 dB to 31 dB shown in FIG. If the attenuation amounts of the input signals of the plurality of ATTs 112 connected in series are all set within the range B, the phase change amount of the input signal can be smoothed even when the gain of the gain control circuit 100 is dynamically adjusted. It can be changed.

  As shown in FIG. 2, in an arbitrary ATT 112, even in a range B where the phase change amount relative to the attenuation amount of the input signal is flat, a range C (attenuation amount of 16 dB to 17 dB) where the phase change amount generated in the input signal is relatively large. Range). When some of the plurality of ATTs 112 connected in series are set with the attenuation amount of the input signal within the range C, a relatively large amount of phase change is superimposed on the input signal. As a result, the input in the gain control circuit 100 There is a high risk that the continuity of the phase change amount with respect to the signal attenuation amount is impaired. Therefore, it is desirable to set the attenuation amount of each input signal of ATT 112a to ATT 112m within a range B so that the ranges C do not overlap. Furthermore, it is preferable to appropriately combine the attenuation amounts of the input signals of ATT 112a to ATT 112m so that the amount of phase change of the input signal in the entire ATT 112a to ATT 112m connected in series is minimized. This is because in the gain control circuit 100, the amount of attenuation of the input signal can be adjusted more dynamically as the amount of phase change that occurs in the input signal is smaller.

  A preferable combination of the attenuation amounts of the input signals set in each of the ATTs 112a to 112m is calculated by calculation in the control unit 116 based on the respective characteristics of the phase changes with respect to the attenuation amount of the input signals. The characteristics of each of ATT 112a to ATT 112m used for this calculation may be acquired by actual measurement of each of ATT 112a to ATT 112m, or each of ATT 112a to ATT 112m may hold the characteristics in advance and control unit 116. It may be provided to the control unit 116 in response to an inquiry from.

  As described above, according to the gain control circuit 100 according to the present embodiment, the attenuation amounts of the input signals of the ATT 112a to the ATT 112m are generated in the input signal within the range B in which the phase change amount with respect to the attenuation amount is flat. Since the range C in which the phase change amount is relatively large is set so as not to overlap, the phase change amount of the input signal when adjusting the gain can be reduced.

  In the present invention, the “range in which the phase change amount relative to the attenuation amount of the input signal is flat” is a range excluding the range A shown in FIG. 2, specifically, the phase when the input signal is attenuated by 1 dB. The range of change is less than 2 degrees. Further, the “range where the phase change amount generated in the input signal is relatively large” shown by the range C in FIG. 2 is specifically that the phase change amount when the input signal is attenuated by 1 dB is 1 degree or more and less than 2 degrees. Refers to a range.

  The wireless transmission device, the wireless reception device, and the wireless measurement device according to the present invention can be formed by incorporating the gain control circuit according to the present invention into these devices by a known means.

  Next, more specific embodiments of the present invention will be described with reference to examples.

  FIG. 3 shows a configuration of the gain control circuit 100 according to the embodiment of the present invention. A gain control circuit 100 shown in FIG. 3 is obtained by connecting three sets of ATTs 112 and amplifiers 113 in series to the gain control circuit 100 shown in FIG. In the gain control circuit 100 according to the present embodiment, the phase change amount with respect to the attenuation amount of the input signal in each of the ATTs 112a, 112b, and 112c is as shown in the graph of FIG. Furthermore, in the gain control circuit 100 according to the present embodiment, a 5-bit parallel signal is used as the setting signal 115, and the attenuation amount of the input signal is set in increments of 1 dB.

  Tables 1 and 2 show examples of set values of attenuation amounts of input signals of the ATTs 112a, 112b, and 112c and combinations thereof.

  Table 1 shows an example of combinations of set values when the attenuation amounts of the input signals of the ATTs 112a, 112b, and 112c are set by increasing side by side in order. On the other hand, Table 2 sets the attenuation amount of each input signal of ATTs 112a, 112b, and 112c by increasing side by side up to 15 dB immediately before reaching the lower limit 16 dB of the range C shown in FIG. This is an example of a combination of setting values when only the ATT 112a is set to increase the upper limit of 31 dB in the range B shown in FIG. 2 and then set by increasing the attenuation of the input signal of the ATT 112b.

  FIG. 4 shows a phase change amount with respect to the total attenuation amount of the input signal in the gain control circuit 100 according to Table 1, and a phase change amount with respect to the total attenuation amount of the input signal in the gain control circuit 100 according to Table 2. And together. As is clear from FIG. 4, the difference in the phase change amount generated in the input signal is large when the total attenuation amount of the input signal is in the range of 47 dB to 49 dB between the case according to Table 1 and the case according to Table 2. It can be seen that the difference is maintained even when the total attenuation of the input signal reaches 65 dB.

  As described above, according to the combination of setting values shown in Table 2, the range C in which the phase change amount generated in the input signal is relatively large is set to be superimposed on the entire ATTs 112a, 112b, and 112c connected in series. As a result, the phase change amount with respect to the sum total of the attenuation amount of the input signal in the gain control circuit 100 can be smoothly shifted, and the phase change amount generated in the input signal can be reduced.

  The gain control method and the gain control circuit according to the present invention can smoothly shift the phase change amount relative to the attenuation amount of the input signal with a simple circuit configuration, and can reduce the phase change amount generated in the input signal. It is advantageous in that it can be used, and is useful as a wireless transmission device, a wireless reception device, a wireless measurement device, and the like.

The block diagram which shows the structure of the gain control circuit in one embodiment which concerns on this invention The figure which shows the characteristic of the digital control attenuator single-piece | unit in one embodiment of this invention The block diagram which shows the structure of the gain control circuit in the Example which concerns on this invention The figure which shows the phase change amount with respect to the attenuation amount of the input signal in the Example which concerns on this invention. Block diagram showing the configuration of a conventional gain control circuit

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Gain control circuit 111 Input terminal 112 Digital control attenuator 113 Amplifier 114 Output terminal 115 Setting signal 116 Control part

Claims (7)

An acquisition step of acquiring the characteristics of each of a plurality of digitally controlled attenuators connected in series with respect to the phase change amount with respect to the attenuation amount of the input signal;
A setting step for setting the attenuation amount of each input signal of the digital control attenuator in a range where the phase change amount with respect to the attenuation amount of the input signal is flat according to the acquired characteristic;
A gain control method comprising: an attenuation step in which the digital control attenuator attenuates the input signal by a set attenuation amount.   In the setting step, a combination of attenuation amounts of the input signals of the digital control attenuators that minimizes the amount of phase change of the input signals in the plurality of digital control attenuators connected in series according to the acquired characteristics is obtained. The gain control method according to claim 1, further comprising: calculating an attenuation amount of each input signal of the digital control attenuator according to the calculated combination. A plurality of digitally controlled attenuators connected in series to attenuate the input signal by a set attenuation,
In accordance with the characteristics of the digital control attenuator with respect to the phase change amount with respect to the attenuation amount of the input signal, the attenuation amount of the input signal of each of the digital control attenuators is set in a range where the phase change amount with respect to the attenuation amount of the input signal is flat. And a control means for setting.   4. The gain control circuit according to claim 3, further comprising an amplifier for amplifying the input signal attenuated by the digital control attenuator.   A radio transmission apparatus comprising the gain control circuit according to claim 3.   A radio receiving apparatus comprising the gain control circuit according to claim 3.   A wireless measuring device comprising the gain control circuit according to claim 3.

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