JP3263017B2 - Detection circuit and transmission device and reception device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection circuit used in a radio transceiver and the like, and to a transmission device and a reception device using the same. More specifically, the linearity range of the detection circuit is not limited to the characteristics of a diode. It is related to the improvement to make.

[0002]

2. Description of the Related Art FIG. 8 is a circuit diagram showing a configuration of a transmitting apparatus using a power control circuit disclosed in Japanese Patent Application Laid-Open No. 7-307699. In the figure, reference numeral 1 denotes a transmission circuit that outputs a transmission signal, 2 denotes a transmission signal amplification circuit that receives the transmission signal, amplifies the transmission signal, and outputs an amplified transmission signal, and 3 denotes the amplified transmission signal. And a diode detection circuit 4 to which one of the distributed transmission signals is input and outputs a detection signal having a level corresponding to the signal power, Reference numeral 5 denotes a power control circuit that controls the amplification factor of the transmission signal amplifier circuit 2 according to the level of the detection signal, and reference numeral 6 denotes a transmission antenna that outputs the other of the distribution transmission signals.

In FIG. 1, reference numeral 7 denotes a capacitor, 8 denotes a rectifying diode to which the output of the capacitor 7 is input, and 9 is connected in series with the diode 8 to generate a detection signal voltage. A detection resistor 10 is connected in parallel with the detection resistor 9 to remove high-frequency components of the detection signal voltage.
The detection signal voltage by the 0 half-wave rectifier circuit is output as a detection signal.

Next, the operation will be described. The transmission signal output from the transmission circuit 1 is amplified by the transmission signal amplifying circuit 2 and then transmitted wirelessly from the transmission antenna 6 via the distribution circuit 3. At this time, the distribution circuit 3 extracts a part of the power of the amplified transmission signal, and outputs the distribution transmission signal to the diode detection circuit 4. In response to this, the diode detection circuit 4 outputs a detection signal having a level obtained by integrating half the power of the distributed transmission signal, and the power control circuit 5 operates the transmission signal so that the detection signal becomes a predetermined level. The amplification factor of the amplifier circuit 2 is controlled. Thus, the transmission signal can be output from the transmission antenna at a constant transmission power regardless of the level of the transmission signal output from the transmission circuit 1 or the fluctuation of the amplification characteristics of the transmission signal amplifier circuit 2.

[0005]

Since the conventional detection circuit and the transmission device and the reception device using the same are configured as described above, the characteristics of the rectifying diode 8 used in the diode detection circuit 4 depend on the characteristics. However, there has been a problem that the detection accuracy of the transmission signal power is limited, and as a result, the stability of the transmission power of the transmission signal is also limited.

More specifically, FIG. 9 is a characteristic diagram showing an example of characteristics of the diode detection circuit 4. In the figure, the horizontal axis is the input power input to the diode detection circuit 4, and the vertical axis is the detection voltage output from the diode detection circuit 4. As the input voltage (input power) increases, a current flows in a series circuit composed of the rectifying diode 8 and the detection resistor 9, and a non-linear voltage is generated in the rectifying diode 8 in accordance with the current. As shown in (2), the output voltage of the detection circuit has a non-linear voltage waveform with respect to the input power. Therefore, for example, in the figure, the range where the detection accuracy of the transmission signal power is ensured,
That is, the control has to be performed in a range of 10 dBm to 18 dBm in which the linearity of the detection voltage with respect to the input power to the detection circuit is ensured.

In the receiver, the above-described diode detection circuit is used to detect a received signal. In this case, similarly, the rectifying diode used in the diode detection circuit is used to receive the signal. There is a problem that the detection accuracy of the signal power is limited.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a detection circuit capable of performing detection without limiting the range width in which linearity is ensured to the characteristics of a diode. And

It is another object of the present invention to provide a transmission device in which the transmission power of a transmission signal is highly stable, and a reception device capable of accurately detecting the signal power of a reception signal.

[0010]

A detection circuit according to the present invention is provided with a plurality of diode detection circuits that receive an input signal and output a level signal corresponding to the signal power, and output from the plurality of diode detection circuits. Level signal power
Output a detection signal having a level corresponding to the sum of
Circuit, and the level between each diode detection circuit and the output circuit.
Installed in the signal transmission path to amplify the level signal level
One or more amplifiers and at least one amplifier
Provided between the output circuit and input to the output circuit
Limiter circuit that limits the level signal below a certain level
And at least one of the limiter circuits is disposed in parallel.
And an improved amplification characteristic improving diode .

A transmitting apparatus according to the present invention includes a transmitting circuit that outputs a transmitting signal, a transmitting signal amplifying circuit that receives the transmitting signal, amplifies the transmitting signal and outputs an amplified transmitting signal, and an amplified transmitting signal. and one distribution circuit for outputting a distributed transmission signal is distributed to two, entered one of the distribution transmission signal, detection of claim 1 Symbol placement outputs a detection signal having a level corresponding to the signal power A power control circuit for controlling an amplification factor of the transmission signal amplifying circuit according to the level of the detection signal; and a transmission antenna for outputting the other of the distributed transmission signals.

A receiving apparatus according to the present invention comprises : a receiving antenna for outputting a received signal corresponding to a received radio wave; one distribution circuit for dividing the received signal into two to output a distributed received signal; one signal is input, according to claim 1 for outputting a detection signal having a level corresponding to the signal power
Serial and detection circuit of the mounting, to determine the reception state based on the level of the detection signal, and has a reception determination circuit for outputting a predetermined reception detection signal.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before describing an embodiment of the present invention, a reference example related to the present invention will be described below.
I do . Reference Example 1. FIG. 1 is a circuit diagram showing a configuration of a transmission device according to Reference Example 1. In the figure, 1 is a transmission circuit that outputs a transmission signal, 2 is the input of the transmission signal,
A transmission signal amplifying circuit for amplifying the transmission signal and outputting an amplified transmission signal; 3, a distribution circuit for distributing the amplified transmission signal into two to output a distributed transmission signal; Is a detection circuit that receives one of the signals and outputs a detection signal having a level corresponding to the signal power.
Is a power control circuit that controls the amplification factor of the transmission signal amplification circuit 2 according to the level of the detection signal, and 6 is a transmission antenna that outputs the other of the distributed transmission signals.
Reference numeral 22 denotes an isolator that insulates the distribution circuit 3 from the transmitting antenna 6.

In FIG . 1, reference numerals 41 and 42 denote diode detection circuits to which the above-mentioned distributed transmission signals are inputted and which output a level signal having a level corresponding to the signal power of the distributed transmission signals, respectively. A low-pass filter for removing high-frequency components of the level signal;
Reference numeral 15 denotes an amplifier for amplifying each of the above level signals, reference numerals 18 and 19 denote amplification factor setting resistors for setting the amplification factors of the respective amplifiers 14 and 15, and reference numeral 23 denotes a combination of the two amplified level signals. An output circuit for outputting a detection signal having a level corresponding to the sum of the levels of the two level signals. Reference numerals 16 and 17 denote buffer amplifiers for adjusting the level of the level signal to an appropriate level for the output circuit 23. The detection circuit 4 is constituted by these.

Reference numeral 7 denotes a capacitor, 8 denotes a rectifying diode to which the output of the capacitor 7 is input, and 9 denotes a rectifying diode connected in series with the rectifying diode 8.
A detection resistor 10 generates a detection signal voltage. A capacitor 10 is connected in parallel with the detection resistor 9 to remove a high-frequency component of the detection signal voltage. These components constitute the diode detection circuits 41 and 42. ing.

In FIG . 1, reference numeral 21 denotes an A / D converter that outputs digital data corresponding to the level of the detection signal, and reference numeral 20 denotes a control unit that outputs a predetermined gain control value based on the digital data. These constitute the power control circuit 5.

In the figure, reference numeral 27 denotes a variable amplifier circuit for performing amplification at an amplification factor corresponding to the above-mentioned amplification factor control value, and reference numeral 28 denotes a fixed amplifier circuit for further amplifying the output of the variable amplifier circuit 27. The transmission signal amplifier circuit 2 is configured.

[0018] Next, the operation will be described. The transmission signal output from the transmission circuit 1 is amplified according to the amplification factor of the variable amplification circuit 27 and the amplification factor of the fixed amplification circuit 28, and then transmitted wirelessly from the transmission antenna 6 via the distribution circuit 3 and the isolator 22. . At this time, the distribution circuit 3 extracts a part of the power of the amplified transmission signal and outputs the distribution transmission signal to the detection circuit 4. Accordingly, the detection circuit 4
Outputs a detection signal having a level corresponding to the power of the distributed transmission signal, the A / D converter 21 converts the detection signal into digital data, and the control unit 20 controls the digital data so that the digital data becomes predetermined data. Outputs the amplification factor control value. Thus, the transmission signal can be output from the transmission antenna 6 with a constant transmission power regardless of the level of the transmission signal output from the transmission circuit 1 or the fluctuation of the amplification characteristics of the transmission signal amplifier circuit 2.

Further, the operation of the detection circuit 4 in such a series of operations in detail. First, the distributed transmission signal is input to two diode detection circuits 41 and 42. Then, each of the diode detection circuits 41 and 42 outputs a level signal having a level obtained by integrating half of the power of the distributed transmission signal. After passing through the low-pass filters 12 and 13, the level signal is amplified by the amplifiers 14 and 15, the level is converted by the buffer amplifiers 16 and 17, and then added by the output circuit 23. Finally, the output circuit 23 outputs a detection signal having a level according to the addition result.

[0020] In Figure 2 the detection circuit 4 according to Reference Example 1, the input-output characteristic of setting the amplification factor of two both by adjusting the gain setting resistors 18 and 19 of the amplifier 14 and 15 are both "1" FIG. 9 is a characteristic diagram of the detection circuit showing the waveforms of FIG. In the figure, the horizontal axis is the input power input to the detection circuit, the vertical axis is the detection voltage output from the detection circuit, the broken line is the characteristic line of the detection circuit 4 according to Reference Example 1, and the solid line is Is a characteristic line obtained by only the diode detection circuits 41 and 42. As is apparent from this figure, in the detection circuit 4 according to the reference example 1, at least 10 dBm to 1
The linearity is ensured in the input power range of 8 dBm, and a wider linearity range can be obtained than the linearity range obtained when a detection circuit is constituted only by the diode detection circuits 41 and 42. Also, the input power level at which the linearity starts to be obtained is 0 dB.
m (0 V), and the characteristics of the detection circuit 4 are improved.

As described above, according to the first embodiment , an input signal is input to the two diode detection circuits 41 and 42, and the sum of the level signals output from the two diode detection circuits 41 and 42 is detected by the detection signal. , The detection signal rises from a position close to 0V. Accordingly, the slope of the detection signal is substantially constant from the vicinity of the rising edge of the detection signal to the upper end range of the diode detection circuits 41 and 42, and a wide linearity range that cannot be obtained by the diode detection circuits 41 and 42 alone is obtained. There is an effect that can be.

Further , even if the amplification characteristics of the diodes 7, 7 vary, it is possible to ensure the matching of the characteristics of the detection circuits 41, 42 by the above adjustment.
There is an effect that a large number of detection circuits having stable characteristics can be obtained even in mass production.

Since the transmission signal is amplified by using such a detection circuit 4, a transmission signal having a small signal power to a transmission signal having a large signal power are compared with those using only one diode detection circuit. Since amplification can be performed widely at the same amplification factor, various transmission signals can be transmitted without causing waveform distortion, and there is an effect that communication quality can be improved.

[0024] Reference Example 2. FIG. 3 is a circuit diagram showing a configuration of the receiving device according to the second embodiment . In the figure, reference numeral 24 denotes a receiving antenna that outputs a received signal corresponding to a received radio wave, 30 denotes a distribution circuit that divides the received signal into two and outputs a distributed received signal,
Is a detection circuit to which one of the distributed reception signals is input and outputs a detection signal having a level corresponding to the signal power, 29 is a circuit for determining a reception state based on the level of the detection signal, and a predetermined reception detection This is a reception determination circuit that outputs a signal. Each circuit showing the internal configuration of the detection circuit 4 is a reference
Since the configuration is the same as that of the detection circuit of Example 1, the same reference numerals are given and the description is omitted.

[0025] Next, the operation will be described. When receiving the radio wave, the receiving antenna 24 outputs a reception signal corresponding to the radio wave, and is transmitted to each unit in the receiving device. At this time, the distribution circuit 30 extracts a part of the power of the reception signal and outputs the distribution reception signal to the detection circuit 4. In response,
The detection circuit 4 outputs a detection signal having a level corresponding to the power of the distributed transmission signal, and the reception determination circuit 29 determines a reception state based on the detection signal and outputs a predetermined reception detection signal. Note that the operation of the detection circuit 4 in such a series of operations is the same as that of the first embodiment, and thus the description is omitted.

As described above, according to the reference example 2, the distributed reception signal is input to the two diode detection circuits 41 and 42, and the sum of the level signals output from the two diode detection circuits 41 and 42 is detected. Since the detection signal is output as a signal, the detection signal rises from a position close to 0V. Accordingly, the slope of the detection signal is substantially constant from the vicinity of the rising edge of the detection signal to the upper end range of the diode detection circuits 41 and 42, and a wide linearity range that cannot be obtained by the diode detection circuits 41 and 42 alone is obtained. There is an effect that can be.

Since the reception signal is detected by using such a detection circuit, the accuracy of the reception signal from a small signal power to a reception signal with a large signal power is higher than that using a single diode detection circuit. Since the detection can be performed well, there is an effect that even if the received signal is weak, it is possible to accurately determine the reception state and output the reception detection signal appropriately.

Reference Example 3 FIG. 4 is a circuit diagram showing a configuration of a transmission device according to the third embodiment . In the figure, 25 is one amplifier 15 and output circuit 2
3 is a Zener diode (limiter circuit) disposed in a level signal path between the first and second circuits. Refer to Example 1 for other configurations.
Therefore, the same reference numerals are given and the description is omitted.

[0029] Next, the operation will be described. When the distributed transmission signal is input, the two diode detection circuits 41 and 42 output a level signal having a level obtained by integrating half the power of the distributed transmission signal. This level signal passes through low-pass filters 12 and 13 and then goes through amplifiers 14 and 15.
, And are level-converted by the buffer amplifiers 16 and 17, and then added by the output circuit 23.

At this time, the level signal provided with the Zener diode 25 is limited to a constant level regardless of the amplification by the amplifier 15. Therefore, at the level of the distributed transmission signal in which one level signal is restricted by the Zener diode 25, the level of the detection signal changes only by the other level signal, and the detection according to the level of the transmission signal is performed. The rate of change of the signal is suppressed.

FIG . 5 shows that in the detection circuit 4 according to the reference example 3, two amplification factor setting resistors 18 and 19 are adjusted to set the amplification factor of the one amplifier 15 to “1.2” and the amplification factor of the other amplifier 14. FIG. 9 is a characteristic diagram of the detection circuit showing input / output characteristics when the rate is set to “1”. In the figure, the one-dot chain line is the characteristic line of the detection circuit 4 according to the reference example 2, the solid line is the characteristic line only by the diode detection circuit 41, and the two-dot chain line is the zener diode 2.
5 is a characteristic line of the level signal provided. Other than this
The description is omitted because it is the same as in Reference Example 1. As is clear from this figure, in the detection circuit 4 according to the reference example 2, the linearity is ensured at least in the input power range of 8 dBm to 18 dBm, and the linearity range (10 dBm to 18 dBm) obtained by the detection circuit of the reference example 1 is obtained.
A wider linearity range than Bm) can be obtained. The input power level at which the linearity starts to be obtained is also at a position close to 0 dBm (0 V), and the characteristics of the detection circuit 4 are improved.

As described above, according to the third embodiment , an input signal is input to the two diode detection circuits 41 and 42, and the sum of the level signals output from the two diode detection circuits 41 and 42 is detected by the detection signal. , The detection signal rises from a position close to 0V. With it,
Since the level signal of one of the diode detection circuits 42 is limited to a predetermined level or less by the limiter circuit 25, the change in the gradient of the range in which linearity is obtained can be suppressed even with the other diode detection circuit 41 alone, so that a smaller value is obtained. Linearity can be ensured from the detected signal. Furthermore, since the level signal outputs of the diode detection circuits 41 and 42 can be separately amplified by the amplifiers 14 and 15, the linearity can be adjusted by appropriately setting the amplification factors of the amplifiers 14 and 15. Therefore, the slope of the detection signal is substantially constant from the vicinity of the rising edge of the detection signal to the upper end range of the diode detection circuits 41 and 42, so that a wider linearity range can be obtained than the detection circuit of the first embodiment. There is.

Since the transmission signal is amplified by using the detection circuit 4 as described above, the transmission signal having a smaller signal power and the transmission signal having a larger signal power than those in the first embodiment are widely amplified with the same amplification factor. It is possible to do
Various transmission signals can be transmitted without waveform distortion, and there is an effect that communication quality can be improved.

[0034] In addition, as it is apparent from the above description, participants
With the detection circuit 4 of Reference Example 3 to the receiving apparatus shown in Reference Example 2, similarly, it can be detected accurately to the received signal of large signal power from the received signal with a small signal power as compared with Reference Example 2 Therefore, there is an effect that even if the reception signal is weak, it is possible to accurately determine the reception state and output the reception detection signal appropriately.

[0035] Embodiment 1. FIG. 6 is a circuit diagram showing a configuration of the transmitting apparatus according to Embodiment 1 of the present invention. In the drawing, reference numeral 26 denotes an amplification characteristic improving diode (diode) arranged in parallel with the Zener diode 25. The other configuration is the same as that of the second embodiment, and thus the same reference numerals are given and the description is omitted.

[0036] Next, the operation will be described. When the distributed transmission signal is input, the two diode detection circuits 41 and 42 output a level signal having a level obtained by integrating half the power of the distributed transmission signal. This level signal passes through low-pass filters 12 and 13 and then goes through amplifiers 14 and 15.
, And are level-converted by the buffer amplifiers 16 and 17, and then added by the output circuit 23.

At this time, the level signal provided with the Zener diode 25 is limited to a constant level regardless of the amplification by the amplifier 15. Therefore, at the level of the distributed transmission signal in which one of the level signals is restricted by the zener diode 15, the level of the detection signal is changed only by the other level signal, and the detection according to the level of the transmission signal is performed. The change rate of the signal is suppressed.

Further, the amplification characteristic improving diodes 26
Accordingly, the level change characteristics of the level signal until the limit by the Zener diode 25 is applied become smooth characteristics. Therefore, the detection signal generated based on this level signal can ensure good linearity even if the matching of the characteristics of the three diodes 8, 8, and 26 is poor.

FIG . 7 is a characteristic diagram of the detection circuit 4 showing input / output characteristics when the two amplification rate setting resistors 18 and 19 are appropriately adjusted in the detection circuit 4 according to the first embodiment of the present invention. In the figure, the solid line on the upper side is the characteristic line of the detection circuit 4 according to the first embodiment, the solid line on the lower side is the characteristic line of only the diode detection circuit 41, and the characteristic indicated by the dotted line. A line is a characteristic line of the level signal provided with the diode 26 for improving the amplification characteristic. Other than this, the description is omitted because it is the same as the reference example 2.
As is clear from this figure, in the detection circuit 4 according to the first embodiment, linearity is secured at least in the input power range of 0 dBm to 18 dBm.
The linearity range (8
A linearity range wider than dBm to 18 dBm) can be obtained. The input power level at which the linearity starts to be obtained is also from 0 dBm (0 V), and very good characteristics are obtained as the detection circuit 4.

As described above, according to the first embodiment, the input signal is input to the two diode detection circuits 41 and 42, and the sum of the level signals output from the two diode detection circuits 41 and 42 is calculated. Since the detection signal is output as a detection signal, the detection signal rises from a position close to 0V. Also, since the level signal of one of the diode detection circuits 42 is limited to a predetermined level or less by the zener diode 25, the inclination of the range in which the linearity is obtained by only the other diode detection circuit 41 is suppressed, and the amplification characteristic improving diode is used. Since the waveform is smoothed by 26, linearity can be secured from a smaller detection signal. At the same time, each diode detection circuit 4
Since the level signal outputs of the amplifiers 14 and 15 can be separately amplified by the amplifiers 14 and 15, the linearity can be adjusted by appropriately setting the amplification factors of the amplifiers 14 and 15. Accordingly, the slope of the detection signal is substantially constant from the vicinity of the rising edge of the detection signal to the upper end range of the diode detection circuits 41 and 42, so that a wider linearity range can be obtained than the detection circuit of the reference example 2. There is.

Since the transmission signal is amplified by using such a detection circuit 4, the transmission signal having a lower signal power than the transmission signal having a higher signal power than that of the reference example 3 is widely amplified at the same amplification factor. It is possible to do
Various transmission signals can be transmitted without waveform distortion, and there is an effect that communication quality can be improved.

[0042] As apparent from the above description, by using the receiver shown the detection circuit 4 of the first embodiment to the second embodiment, likewise, small signal power in comparison with Reference Example 3 Since it is possible to accurately detect a received signal to a received signal having a large signal power, even if the received signal is weak, it is possible to accurately determine a reception state and output a received detection signal appropriately. .

[0043]

As is evident from the foregoing description, according to the present invention, a plurality of diode detection circuit for outputting a level signal corresponding to the signal power is output from the plurality of diode detector circuit
Detection having a level corresponding to the sum of the powers of the level signals
An output circuit that outputs a signal, and each diode detection circuit
The level signal transmission path between the
One or more amplifiers to amplify the signal level,
Are provided between one amplifier and the output circuit.
Limits the level signal input to the input circuit to a specified level or less
Limiter circuit and at least one limiter circuit
A diode for improving the amplification characteristics
The level signal of each diode detector
Signal output can be amplified separately by an amplifier.
By properly setting the amplification factor of the
Than when the level signal output of the ion detection circuit is added
It is possible to secure a wider linearity range
There is an effect. In this case, at least one amplifier
Between the output circuit and the level signal input to the output circuit.
A limiter circuit is provided to limit the signal to below a certain level.
To ensure linearity from smaller detection signals
can do. It is also installed in parallel with the limiter circuit.
Due to the characteristics of the improved diode for improving amplification characteristics , the rise of the detection signal from around 0 V can be improved, and a wider linearity range can be secured than in the case of a circuit configuration combining a diode detection circuit and an amplifier. There is a possible effect.

When the transmission signal is amplified by using the above-described detection circuit, the transmission signal having a small signal power to the transmission signal having a large signal power can be widely used as compared with the case of using only one diode detection circuit. Therefore, various transmission signals can be transmitted without waveform distortion, and the communication quality can be improved.

[0045] Similarly, by detecting the received signal using a detection circuit as described above, merely compared with those using a single diode detection signal, the accuracy to large signal power received signal from the reception signal of small signal power Since detection can be performed well, there is an effect that even if the reception signal is weak, the reception state can be accurately determined and the reception detection signal can be appropriately output.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a configuration of a transmission device according to a reference example 1.

FIG. 2 is a characteristic diagram of a detection circuit showing a characteristic example of the detection circuit according to Reference Example 1;

FIG. 3 is a circuit diagram illustrating a configuration of a receiving device according to a reference example 2.

FIG. 4 is a circuit diagram illustrating a configuration of a transmission device according to a third embodiment .

FIG. 5 is a characteristic diagram of a detection circuit showing a characteristic example of the detection circuit according to Reference Example 3;

FIG. 6 is a circuit diagram showing a configuration of a transmitting apparatus according to Embodiment 1 of the present invention.

FIG. 7 is a characteristic diagram of the detection circuit showing input / output characteristics when two amplification rate setting resistors are appropriately adjusted in the detection circuit according to the first embodiment of the present invention;

FIG. 8 is a circuit diagram showing a configuration of a conventional transmission device.

FIG. 9 is a characteristic diagram illustrating a characteristic example of a diode detection circuit in a conventional transmission device.

[Explanation of symbols]

1 transmission circuit, 2 transmission signal amplification circuit, 3, 30 distribution circuit, 4 detection circuit, 5 power control circuit, 6 transmission antenna, 14, 15 amplifier, 23 output circuit, 24 reception antenna, 25 zener diode (limiter circuit), 26 Diode (diode) for improving amplification characteristics, 29 Reception discrimination circuit, 41, 42 Diode detection circuit.

Continuation of front page (56) References JP-A-3-198508 (JP, A) JP-A-10-145160 (JP, A) JP-A-9-36684 (JP, A) JP-A-5-48357 (JP) JP-A-5-29968 (JP, A) JP-A-61-131917 (JP, A) JP-A-57-113634 (JP, A) JP-A-61-18644 (JP, U) JP-A-61-18644 (JP, U) 58-129706 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 1/02-1/04 H03G 1/00-3/34 H04B 7/26

Claims (3)

(57) [Claims] 1. A plurality of diode detection circuits receiving an input signal and outputting a level signal corresponding to the signal power, and a level detector output from the plurality of diode detection circuits.
Detection signal having a level corresponding to the sum of the power of the
Output circuit to output, each diode detection circuit and output circuit
Is provided in the level signal transmission path between
One or more amplifiers for amplifying levels, and at least one
Between the two amplifiers and the output circuit.
To limit the level signal input to
A limiter circuit and at least one of the limiter circuits.
A detection circuit comprising: an amplification characteristic improving diode disposed in a row . 2. A transmission circuit for outputting a transmission signal, a transmission signal amplification circuit for receiving the transmission signal, amplifying the transmission signal and outputting an amplified transmission signal, and distributing the amplified transmission signal into two. and one distribution circuit for outputting a distributed transmission signal Te is input one of the distribution transmission signal, a detector circuit according to claim 1 Symbol <br/> mounting and outputs a detection signal having a level corresponding to the signal power And a power control circuit for controlling an amplification factor of the transmission signal amplification circuit according to the level of the detection signal, and a transmission antenna for outputting the other of the divided transmission signals. 3. A receiving antenna for outputting a received signal corresponding to a received radio wave, one distribution circuit for distributing the received signal into two and outputting a distributed received signal, and one of the distributed received signals is inputted. , reception determining circuit determines a detection circuit according to claim 1 Symbol placement outputs a detection signal having a level corresponding to the signal power, the reception state based on the level of the detection signal and outputs a predetermined reception detection signal A receiving device comprising: