JP2015070379A - Detection circuit and detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detection circuit capable of enlarging an apparent dynamic range of a detector while suppressing expansion of circuit scale.SOLUTION: A detection circuit 100 includes: an attenuator 18 in which an output signal is attenuated and outputted; an amplifier 12 in which the output signal outputted from the attenuator is amplified and outputted; a branch part 14 in which the output signal outputted from the amplifier is branched and a branch signal is extracted from the output signal; a variable gain amplifier 15 in which the branch signal is amplified and outputted; a detection part 16 which detects the branch signal outputted from the variable gain amplifier and outputs a detection voltage which has a value corresponding to a signal level of the branch signal and of which the linear property is changed at a predetermined inflection point voltage; and a control circuit 17 which adjusts an attenuation amount for the attenuator to attenuate the output signal on the basis of the detection voltage, compares the detection voltage with the inflection point voltage and adjusts an amplification amount for the variable gain amplifier to amplify the branch signal on the basis of a result of the comparison and the adjusted attenuation amount.

Description

  The present invention relates to a detection circuit and a detection method.

  In various circuits, a detector for detecting a change in the signal level of the output signal is used to accurately control the signal level of the output signal output from the amplifier. The detector detects a change in the signal level by outputting a detection voltage having a value corresponding to the signal level of the input signal. However, in such a detector, since the range of detectable signal levels (hereinafter referred to as dynamic range) is determined, there is a limit to the range in which the signal level of the output signal can be controlled.

  On the other hand, in Patent Documents 1 and 2, the signal level of the output signal is adjusted and input to the detector, and the adjustment amount by adjusting the signal level and the signal input to the detector are detected. A technique for detecting the signal level of the original output signal based on the signal level is described. As a result, the apparent dynamic range, which is the range in which the detector can detect the signal level of the original output signal, can be expanded. In such a technique, it is necessary to adjust the signal level so that the signal level of the signal input to the detector falls within the actual dynamic range of the detector.

  The detection circuit described in Patent Document 1 is based on a control signal output from an external device such as a base station, so that the signal level of the signal input to the detector falls within the actual dynamic range of the detector. The amount of attenuation that attenuates the input signal is adjusted.

  The detection circuit described in Patent Document 2 includes a variable high-frequency attenuator that adjusts the signal level of a signal input to the detector, and a DC amplifier that amplifies the detection voltage from the detector. This detection circuit feeds back the signal input to the detector so that the signal level of the signal input to the detector falls within the actual dynamic range of the detector by feeding back the output of the DC amplifier to the variable high-frequency amplifier. The amount of attenuation is adjusted.

JP 05-152977 A JP-A-62-210728

  However, since the detection circuit described in Patent Document 1 adjusts the amount of attenuation based on a control signal output from an external device such as a base station, a configuration for receiving this control signal is necessary, and the circuit scale is large. Will increase. Further, the detection circuit described in Patent Document 2 requires a DC amplifier that amplifies the detection voltage and feet back to the variable high-frequency attenuator, which increases the circuit scale.

  An object of the present invention is to provide a detection circuit and a detection method capable of expanding an apparent dynamic range of a detector while suppressing an increase in circuit scale.

The detection circuit according to the present invention comprises:
An attenuator that attenuates and outputs the output signal;
An amplifier that amplifies and outputs the output signal output from the attenuator;
A branching unit that branches the output signal output from the amplifier and extracts a branching signal from the output signal;
A variable gain amplifier for amplifying and outputting the branched signal;
Detecting a branch signal output from the variable gain amplifier, having a value corresponding to the signal level of the branch signal, and outputting a detection voltage whose linear characteristic changes at a predetermined inflection point voltage; and
Based on the detected voltage, the attenuator adjusts an attenuation amount for attenuating the output signal, compares the detected voltage with the inflection point voltage, and based on the comparison result and the adjusted attenuation amount. The variable gain amplifier includes a control circuit for adjusting an amplification amount for amplifying the branch signal.

Further, the detection method according to the present invention includes:
An attenuator that attenuates and outputs the output signal;
An amplifier that amplifies and outputs the output signal output from the attenuator;
A branching unit that branches the output signal output from the amplifier and extracts a branching signal from the output signal;
A variable gain amplifier for amplifying and outputting the branched signal;
Detecting a branch signal output from the variable gain amplifier, and having a value corresponding to the signal level of the branch signal and outputting a detection voltage whose linear characteristic changes at a predetermined inflection point voltage; The detection circuit provided is
Based on the detection voltage, the attenuator adjusts an attenuation amount by which the output signal is attenuated,
Comparing the detected voltage and the inflection point voltage;
Based on the comparison result and the adjusted attenuation amount, the variable gain amplifier adjusts an amplification amount for amplifying the branch signal.

  According to the present invention, it is possible to increase the apparent dynamic range of the detector while suppressing an increase in circuit scale.

It is a block diagram which shows the structure of the detection circuit concerning one Embodiment of this invention. It is a graph which shows the characteristic of the detection voltage output with respect to the signal level of the signal into which the detection diode was input. It is a graph for demonstrating the relationship of the attenuation amount used with respect to the attenuation amount control voltage to which the attenuator was applied. It is a graph for demonstrating the relationship of the amount of amplification used with respect to the gain control voltage to which the variable gain amplifier was applied. It is a figure for demonstrating adjustment of the amount of amplification which a detection circuit performs. It is a figure for demonstrating the change of the dynamic range of a detection diode by adjustment of amplification amount. It is a figure which shows the characteristic of the detection diode in the modification of this invention. It is a figure for demonstrating adjustment of the amplification amount in a modification. It is a figure for demonstrating the change of the dynamic range of a detection diode by adjustment of the amount of amplification in a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in this specification and drawing, the description which overlaps may be abbreviate | omitted by attaching | subjecting the same code | symbol about the component which has the same function.

  FIG. 1 is a block diagram showing a configuration of a detection circuit 100 according to an embodiment of the present invention.

  A detection circuit 100 shown in FIG. 1 includes an input terminal 11, an amplifier 12, an output terminal 13, a coupler 14, a variable gain amplifier 15, a detection diode 16, a voltage control circuit 17, and an attenuator (ATT). 18. The detection circuit 100 further includes a first resistor 21, a first capacitor 22, a first coil 23, a second resistor 24, a second coil 25, and a second capacitor 26.

  The input terminal 11 is an input port that receives an RF (Radio Frequency) signal, and is connected to the input side of the amplifier 12. The output side of the amplifier 12 is connected to the output terminal 13, and the amplifier 12 amplifies the RF signal input from the input terminal 11 with a predetermined gain and outputs the amplified signal. The output terminal 13 is an output port that outputs the RF signal output from the amplifier 12.

  A coupler 14 is provided between the amplifier 12 and the output terminal 13. The coupler 14 is a branch unit that branches the RF signal output from the amplifier 12 and extracts the branch signal from the RF signal. The coupler 14 is connected to a variable gain amplifier (VGA) 15 and a first resistor 21 having one end grounded, and outputs a branch signal extracted from the RF signal to the variable gain amplifier 15. The RF signal from which the branch signal is extracted is output from the output terminal 13.

  The output side of the variable gain amplifier 15 is connected to the detection diode 16 and amplifies the branch signal taken out by the coupler 14 and outputs the amplified signal to the detection diode 16.

  The detection diode 16 is a detection unit that detects the branch signal output from the variable gain amplifier 15 and outputs a detection voltage Vdet indicating the detection result. Specifically, the detection voltage Vdet has a value corresponding to the signal level of the input branch signal, and the linear characteristic changes at a predetermined inflection point voltage. The detection voltage Vdet output from the detection diode 16 is input to the voltage control circuit 17.

  FIG. 2 is a graph showing the relationship of the detection voltage with respect to the signal level of the signal input to the detection diode 16. In the detection diode 16, the linear characteristic of the detection voltage with respect to the signal level of the input signal changes before and after the inflection point voltage Vdet_ref, and the change amount of the detection voltage with respect to the change amount of the signal level is before and after the inflection point voltage Vdet_ref. Different. The dynamic range of the detection diode 16 is determined by the signal level Pin_min corresponding to the lower limit Vdet_min of the detection voltage output from the detection diode 16 and the signal level Pin_max corresponding to the upper limit Vdet_max of the detection voltage.

  Returning to the description of FIG.

  The voltage control circuit 17 is a control circuit that adjusts an amplification amount Gain that the variable gain amplifier 15 amplifies the branch signal and an attenuation amount ATT that attenuates the RF signal based on the detection voltage Vdet. The voltage control circuit 17 is connected to the control terminal of the variable gain amplifier 15 and adjusts the gain Gain of the variable gain amplifier 15 by changing the gain control voltage Vvga applied to the control terminal of the variable gain amplifier 15. . The voltage control circuit 17 is connected to the control terminal of the attenuator 18 and adjusts the attenuation amount ATT of the attenuator 18 by changing the attenuation amount control voltage Vatt applied to the control terminal of the attenuator 18.

  The attenuator 18 is connected to a path connecting the input terminal 11 and the amplifier 12, and is an attenuator that attenuates an RF signal input to the input terminal 11 and inputs the attenuated RF signal to the amplifier 12.

  The first capacitor 22, the first coil 23 having one end grounded, and the second resistor 24 having one end grounded are connected to the path connecting the detection diode 16 and the voltage control circuit 17. . The voltage control circuit 17 is connected to the attenuator 18 via the second coil 25, and the attenuator 18 is connected to a path connecting the input terminal 11 and the amplifier 12 via the second capacitor 26.

  In the detection circuit 100 described above, when the input terminal 11 receives an RF signal, the RF signal is attenuated by the attenuator 18 and input to the amplifier 12. The RF signal input to the amplifier 12 is amplified with a predetermined gain, then branched by the coupler 14 and partly output from the output terminal 13, and the remaining branch signal is input to the variable gain amplifier 15. The branch signal input to the variable gain amplifier 15 is amplified and then input to the detection diode 16.

  When the branch signal is input to the detection diode 16, the detection diode 16 detects the branch signal output from the variable gain amplifier 15, has a value corresponding to the signal level of the branch signal, and has a predetermined inflection point voltage. The detection voltage Vdet whose linear characteristic changes is output.

  The detection voltage Vdet output from the detection diode 16 is input to the voltage control circuit 17. The voltage control circuit 17 adjusts the attenuation amount ATT of the attenuator 18 based on the input detection voltage Vdet, and based on the adjusted attenuation amount ATT, the detection voltage Vdet, and the inflection point voltage Vdet_ref of the detection diode 16. Then, the amplification amount Gain of the variable gain amplifier 15 is adjusted.

  Hereinafter, specific processing of the voltage control circuit 17 will be described. The voltage control circuit 17 increases or decreases the attenuation amount ATT of the attenuator 18 according to the increase or decrease of the detection voltage Vdet. When the detection voltage Vdet increases, the voltage control circuit 17 increases the attenuation amount ATT and decreases the signal level of the RF signal input to the amplifier 12. When the detection voltage Vdet decreases, the voltage control circuit 17 decreases the attenuation amount ATT and increases the signal level of the RF signal input to the amplifier 12.

  The voltage control circuit 17 increases the amplification amount Gain when the adjusted attenuation amount ATT is increased, and increases the amplification amount Gain when the adjusted attenuation amount ATT is decreased. At this time, the voltage control circuit 17 compares the detection voltage Vdet and the inflection point voltage Vdet_ref and adjusts the amplification amount Gain based on the comparison result. Specifically, the voltage control circuit 17 performs amplification so that the magnitude relationship between the attenuation amount ATT and the amplification amount Gain changes according to the magnitude relationship between the detection voltage Vdet and the inflection point voltage Vdet_ref indicated by the comparison result. Adjust the amount Gain.

  The amplification amount Gain adjusted by the voltage control circuit 17 varies depending on the characteristics of the attenuator 18, the variable gain amplifier 15, and the detection diode 16, and will be described more specifically with an example of these characteristics. The detection diode 16 has the characteristics shown in FIG.

  FIG. 3 is a graph showing an example of the relationship between the attenuation control voltage Vatt applied to the attenuator 18 and the attenuation ATT. The attenuation amount ATT takes a value between the minimum value ATT_min and the maximum value ATT_max, and the attenuation amount control voltage Vatt for setting the attenuation amount ATT takes a value between the minimum value Vatt_min and the maximum value Vatt_max. The relationship between the attenuation amount ATT and the attenuation amount control voltage Vatt is linear.

  FIG. 4 is a graph showing an example of the relationship between the gain control voltage Vvga applied to the variable gain amplifier 15 and the amplification amount Gain. The amplification amount Gain takes a value between the minimum value Gain_min and the maximum value Gain_max, and the amplification amount control voltage Vvga for setting the amplification amount Gain takes a value between the minimum value Vvga_min and the maximum value Vvga_max. The relationship between the amplification amount Gain and the amplification amount control voltage Vvga is linear.

  In this example, as shown in FIG. 2, when the signal level of the branch signal input from the detection diode 16 is higher than the signal level Pin_ref corresponding to the inflection point voltage Vdet_ref, the signal level is lower than Pin_ref. Thus, the change amount of the detection voltage Vdet with respect to the change of the signal level is small.

  FIG. 5 is a graph showing the relationship between the attenuation control voltage Vatt applied to the attenuator 18, the attenuation ATT in the attenuator 18 and the amplification gain Gain in the variable gain amplifier 15. Here, the attenuation control voltage Vatt corresponding to the detection voltage Vdet having the same value as the inflection point voltage Vdet_ref is defined as the inflection point attenuation control voltage Vatt_ref.

  When the detection voltage Vdet is larger than the inflection point voltage Vdet_ref, the voltage control circuit 17 makes the amplification amount Gain larger than the attenuation amount ATT, and when the detection voltage Vdet is smaller than the inflection point voltage Vdet_ref, the voltage control circuit 17 sets the amplification amount Gain. The attenuation amount is set to be smaller than ATT.

  FIG. 6 shows the relationship between the detection voltage Vdet output with respect to the signal level of the signal input to the detection diode when the amplification amount Gain is adjusted based on the comparison result between the detection voltage Vdet and the inflection point voltage Vdet_ref. It is a graph to show.

  In the detection diode 16, the linear characteristic of the detection voltage Vdet with respect to the change in signal level changes depending on whether or not the detection voltage Vdet is larger than the inflection point voltage Vdet_ref. Therefore, the voltage control circuit 17 adjusts the amplification amount Gain so that the magnitude relationship between the amplification amount Gain and the attenuation amount ATT changes depending on whether or not the detection voltage Vdet is larger than the inflection point voltage Vdet_ref. It is possible to reduce the amount of change in the detection voltage Vdet with respect to the change in the signal level of the output signal. Therefore, the apparent dynamic range of the detection diode 16 is expanded.

(Modification)
FIG. 7 is a diagram for explaining a modification in which the characteristics of the detection diode 16 are different.

  In the above example, the detection diode 16 detects the detection voltage with respect to the signal level of the input signal when the detection voltage Vdet is larger than the inflection point voltage Vdet_ref than when the detection voltage Vdet is smaller than the inflection point voltage Vdet_ref. The change in Vdet was small. On the other hand, in this modification, the detection diode 16 is configured such that when the detection voltage Vdet is larger than the inflection point voltage Vdet_ref, the detection signal Vdet is smaller than the case where the detection voltage Vdet is smaller than the inflection point voltage Vdet_ref. The change in the detection voltage Vdet with respect to the signal level is large.

  As described above, when the characteristics of the detection diode 16 are different, compared to the above example, in this modification, the magnitude relationship between the detection voltage Vdet and the inflection point voltage Vdet_ref, the amplification amount Gain, and the attenuation amount ATT are compared. Correspondence with the magnitude relationship is reversed.

  FIG. 8 is a graph showing the relationship between the attenuation control voltage Vatt applied to the attenuator 18, the attenuation ATT at the attenuator 18 and the gain Gain at the variable gain amplifier 15 in this modification. In the present modification, when the detection voltage Vdet is larger than the inflection point voltage Vdet_ref, the voltage control circuit 17 makes the amplification amount Gain smaller than the attenuation amount ATT, and the detection voltage Vdet is smaller than the inflection point voltage Vdet_ref. The amplification amount Gain is made larger than the attenuation amount ATT.

  Thereby, the characteristic of the detection voltage Vdet output according to the signal level of the signal input to the detection diode 16 in this modification is adjusted as shown in FIG. 9, and the change of the detection voltage Vdet with respect to the change of the signal level. It is possible to reduce the amount. Therefore, the dynamic range of the detection diode 16 is expanded.

  As described above, according to the present embodiment, the attenuation amount for attenuating the output signal based on the detection voltage output from the detection diode 16 and the inflection point voltage at which the linear characteristic of the detection voltage changes, The amplification amount for amplifying the branch signal input to the detection diode 16 is adjusted. As a result, it is not necessary to provide a configuration for receiving a control signal from an external device, and it is not necessary to provide a component only for feeding back the detected signal to the variable gain amplifier 15, thereby suppressing an increase in circuit scale. However, the apparent dynamic range of the detection diode 16 can be expanded.

  Further, according to the present embodiment, the amplification amount is adjusted so that the magnitude relationship with the attenuation amount changes according to the comparison result between the detection voltage and the inflection point voltage. Thereby, since the amount of change in the detection voltage with respect to the amount of change in the signal level of the output signal can be reduced, the apparent dynamic range of the detection diode 16 can be expanded more reliably. Furthermore, in this case, since the change in the inflection point voltage of the linear characteristic of the detection voltage with respect to the signal level of the output signal can be reduced, the detection diode 16 can detect the change in the signal level more accurately.

  While the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

100 detector circuit 11 input terminal 12 amplifier 13 output terminal 14 coupler (branch part)
15 Variable gain amplifier 16 Detection diode (detection unit)
17 Voltage control circuit (control circuit)
18 Attenuator

Claims (6)

An attenuator that attenuates and outputs the output signal;
An amplifier that amplifies and outputs the output signal output from the attenuator;
A branching unit that branches the output signal output from the amplifier and extracts a branching signal from the output signal;
A variable gain amplifier for amplifying and outputting the branched signal;
Detecting a branch signal output from the variable gain amplifier, having a value corresponding to the signal level of the branch signal, and outputting a detection voltage whose linear characteristic changes at a predetermined inflection point voltage; and
Based on the detected voltage, the attenuator adjusts an attenuation amount for attenuating the output signal, compares the detected voltage with the inflection point voltage, and based on the comparison result and the adjusted attenuation amount. And a control circuit for adjusting an amplification amount by which the variable gain amplifier amplifies the branch signal. The detection circuit according to claim 1,
The control circuit is a detection circuit that adjusts the amplification amount so that a magnitude relationship between the attenuation amount changes according to a magnitude relationship between the detection voltage and the inflection point voltage indicated by the comparison result. The detection circuit according to claim 1 or 2,
The control circuit increases the amount of amplification when the amount of attenuation is increased, and reduces the amount of amplification when the amount of attenuation is decreased. The detection circuit according to any one of claims 1 to 3,
The attenuator attenuates the output signal according to the input attenuation control voltage,
The detection circuit adjusts the attenuation amount by changing the attenuation amount control voltage. The detection circuit according to any one of claims 1 to 4,
The variable gain amplifier amplifies the output signal in accordance with an input amplification amount control voltage,
The detection circuit adjusts the amplification amount by changing the amplification amount control voltage. An attenuator that attenuates and outputs the output signal;
An amplifier that amplifies and outputs the output signal output from the attenuator;
A branching unit that branches the output signal output from the amplifier and extracts a branching signal from the output signal;
A variable gain amplifier for amplifying and outputting the branched signal;
Detecting a branch signal output from the variable gain amplifier, and having a value corresponding to the signal level of the branch signal and outputting a detection voltage whose linear characteristic changes at a predetermined inflection point voltage; The detection circuit provided is
Based on the detection voltage, the attenuator adjusts an attenuation amount by which the output signal is attenuated,
Comparing the detected voltage and the inflection point voltage;
A detection method in which the variable gain amplifier adjusts an amplification amount for amplifying the branch signal based on the comparison result and the adjusted attenuation amount.

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