JPH11127084A - Detecting circuit, and transmission device and reception device using the circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect range width with which linearlity is secured without being limited by characteristics of a diode by outputting a detection signal having a level corresponding to the total of the electric power of more than one level signal. SOLUTION: A transmit signal after being amplified according to the amplification factor of a variable amplifying circuit 27 and a fixed amplifying circuit is transmitted by radio through a distributing circuit 3 and an isolator 22. At this time, the distributing circuit 3 takes some electric power out of the amplified transmit signal and outputs its distributed transmit signal to the detecting circuit 4. The detecting circuit 4 outputs the detection signal having the level corresponding to the electric power of the distributed transmit signal, an A/D converter 21 converts the detection signal into digital data, and a control part 20 outputs an amplification factor control value so that the digital data will be specific digital data. In this case, an input signal is inputted to two diode detecting circuits 41 and 42 of the detecting circuit 4 and the sum of the level signals outputted from the diode detecting circuits 41 and 42 is outputted as a detection signal.

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 has a plurality of diode detection circuits to which an input signal is input and outputs a level signal corresponding to the signal power, and a total sum of the powers of the plurality of level signals. And an output circuit for outputting a detection signal having a level corresponding to

The detection circuit according to the present invention has at least one
Between the two diode detection circuits and the output circuit, a limiter circuit for limiting a level signal input to the output circuit to a predetermined level or less is provided.

A detection circuit according to the present invention includes a plurality of diode detection circuits for outputting a level signal corresponding to the input signal power, and an output for outputting a detection signal having a level corresponding to the sum of the power of the plurality of level signals. The circuit includes a circuit and one or more amplifiers disposed on a level signal transmission path between each diode detection circuit and the output circuit, and amplifying the level of the level signal.

The detection circuit according to the present invention has at least one
The two amplifiers are configured such that their amplification characteristics can be adjusted.

The detection circuit according to the present invention has at least one
Between one amplifier and the output circuit, one or a plurality of limiter circuits for limiting a level signal input to the output circuit to a predetermined level or less are provided.

The detection circuit according to the present invention has at least one
One of the limiter circuits is provided with a diode in parallel therewith.

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. 3. A distribution circuit for distributing the signal to two and outputting a distributed transmission signal, and one of the distributed transmission signals being input and outputting a detection signal having a level corresponding to the signal power. A detection circuit; a power control circuit for controlling an amplification factor of the transmission signal amplifying circuit according to a 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; a distribution circuit for dividing the received signal into two and outputting a distributed received signal;
3. The detection circuit according to claim 1, wherein one of the distributed reception signals is input and outputs a detection signal having a level corresponding to the signal power, and a reception state is determined based on the level of the detection signal. , And a reception determining circuit that outputs a predetermined reception detection signal.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 is a circuit diagram showing a configuration of a transmitting apparatus according to Embodiment 1 of the present invention. 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. Is a distribution circuit that outputs a distributed transmission signal by dividing the signal into two, and 4 is a detection circuit that receives one of the distributed transmission signals and outputs a detection signal having a level corresponding to the signal power. Is a power control circuit for controlling the amplification factor of the transmission signal amplifying circuit 2 in accordance with the level of the detection signal, 6 is a transmission antenna for outputting the other of the distributed transmission signals, and 22 is a transmission antenna for transmitting to the distribution circuit 3 This is an isolator that insulates the antenna 6.

In FIG. 1, reference numerals 41 and 42 denote diode detection circuits to which the distributed transmission signal is input and output a level signal having a level corresponding to the signal power of the distributed transmission signal, 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 for outputting digital data corresponding to the level of the detection signal, and reference numeral 20 denotes a control unit for outputting 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.

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.

The operation of the detection circuit 4 in such a series of operations will be described 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.

FIG. 2 shows a case where the two amplification factor setting resistors 18 and 19 are adjusted to set the amplification factors of both the amplifiers 14 and 15 to "1" in the detection circuit 4 according to the first embodiment of the present invention. FIG. 4 is a characteristic diagram of a detection circuit showing input / output characteristics 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, and the dashed characteristic line is the detection circuit 4 according to the first embodiment.
And the solid characteristic line is a characteristic line formed only by the diode detection circuits 41 and 42. As is apparent from this figure, in the detection circuit 4 according to the first embodiment, the linearity is ensured at least in the input power range of 10 dBm to 18 dBm, and the detection circuit is configured only by the diode detection circuits 41 and 42. Thus, a wider linearity range can be obtained than the linearity range obtained in (1). 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 first embodiment, the input signals are 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. 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 and 7 vary, the above adjustment can ensure the matching of the characteristics of the detection circuits 41 and 42,
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.

Embodiment 2 FIG. 3 is a circuit diagram showing a configuration of a receiving apparatus according to Embodiment 2 of the present invention. 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, and 4 denotes a distributed receiving signal. A detection circuit to which one is inputted and which outputs a detection signal having a level corresponding to the signal power, 29 is a reception judgment for judging a reception state based on the level of the detection signal and outputting a predetermined reception detection signal Circuit. Since each circuit showing the internal configuration of the detection circuit 4 has the same configuration as the detection circuit of the first embodiment, the same reference numerals are given and the description is omitted.

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 a description thereof will be omitted.

As described above, according to the second embodiment, the distributed reception signal is input to the two diode detection circuits 41 and 42, and the two diode detection circuits 41 and 42 are input.
Since the sum of the level signals output from the first and second detectors is output as a detection signal, the detection signal rises from a position close to 0V.
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, and the diode detection circuits 41 and 4 have a constant slope.
There is an effect that a wide linearity range that cannot be obtained by only 2 can be obtained.

Since the received signal is detected by using such a detection circuit, the accuracy of the received signal from a small signal power to a received signal with a large signal power is higher than that obtained by using only one 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.

Embodiment 3 FIG. 4 is a circuit diagram showing a configuration of a transmitting apparatus according to Embodiment 3 of the present invention. In the figure, reference numeral 25 denotes a zener diode (limiter circuit) disposed on a level signal path between one amplifier 15 and the output circuit 23. The other configuration is the same as that of the first embodiment, and thus the same reference numerals are given and the description is omitted.

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 third embodiment of the present invention, the two amplification factor setting resistors 18 and 19 are adjusted to set the amplification factor of the one amplifier 15 to "1.2".
FIG. 9 is a characteristic diagram of a detection circuit showing input / output characteristics when the amplification factor of the other amplifier is set to “1”. In the figure,
The dashed line indicates the detection circuit 4 according to the second embodiment.
The solid line is a characteristic line of the diode detection circuit 41 alone, and the two-dot chain line is a characteristic line of the level signal provided with the Zener diode 25. The rest is the same as in the first embodiment, and a description thereof will be omitted. As is apparent from this figure, in the detection circuit 4 according to the second embodiment, at least 8 dBm to 1
The linearity is secured in the input power range of 8 dBm, and a wider linearity range than the linearity range (10 dBm to 18 dBm) obtained by the detection circuit of the first embodiment can be obtained. The input power level at which the linearity starts to be obtained is also 0 dBm (0
V), and the characteristics of the detection circuit 4 are improved.

As described above, according to the third embodiment, the input signals are 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. At the same time, the level signal of one diode detection circuit 42 is limited to a predetermined level or less by the limiter circuit 25.
Since the change in the gradient of the range in which the linearity is obtained can be suppressed only by the other diode detection circuit 41, the linearity can be secured from a smaller detection signal. Further, each diode detection circuit 41, 42
Can be separately amplified by the amplifiers 14 and 15, so that 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. effective.

Since the transmission signal is amplified by using such a detection circuit 4, the transmission signal having a smaller signal power than the transmission signal having a larger signal power than that of the first embodiment is widely used at the same amplification factor. Since amplification can be performed, various transmission signals can be transmitted without causing waveform distortion, and there is an effect that communication quality can be improved.

As is apparent from the above description, when the detection circuit 4 according to the third embodiment is used in the receiving apparatus according to the second embodiment, the signal power is similarly reduced as compared with the second embodiment. From the received signal to the received signal with large signal power, it is possible to accurately determine the receiving state even if the received signal is weak, and to output the received detection signal appropriately. is there.

Embodiment 4 FIG. FIG. 6 is a circuit diagram showing a configuration of a transmitting apparatus according to Embodiment 4 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, so that the same reference numerals are given and the description is omitted.

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.

The amplification characteristic improving diode 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 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 fourth 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 fourth embodiment, the solid line on the lower side is the characteristic line of the diode detection circuit 41 only, A line is a characteristic line of the level signal provided with the diode 26 for improving the amplification characteristic. Except for this, the configuration is the same as that of the second embodiment, and a description thereof will be omitted. As is apparent from this figure, in the detection circuit 4 according to the fourth embodiment, at least 0 dBm to 18 dB
The linearity is secured in the input power range of m, and a wider linearity range than the linearity range (8 dBm to 18 dBm) obtained by the detection circuit of the second embodiment can be obtained. The input power level at which the linearity starts to be obtained is also 0 dBm (0 V).
Thus, a very good characteristic is obtained as the detection circuit 4.

As described above, according to the fourth 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. 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, and a wider linearity range can be obtained than the detection circuit of the second embodiment. effective.

Since the transmission signal is amplified by using such a detection circuit 4, the transmission signal having a smaller signal power to the transmission signal having a larger signal power than in the third embodiment is widely used at the same amplification factor. Since amplification can be performed, various transmission signals can be transmitted without causing waveform distortion, and there is an effect that communication quality can be improved.

As is apparent from the above description, when the detection circuit 4 according to the fourth embodiment is used in the receiving apparatus according to the second embodiment, the signal power is similarly smaller than that in the third embodiment. From the received signal to the received signal with large signal power, it is possible to accurately determine the receiving state even if the received signal is weak, and to output the received detection signal appropriately. is there.

[0048]

As described above, according to the present invention, an input signal is input to a plurality of diode detection circuits, and the sum of level signals output from the plurality of diode detection circuits is output as a 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 circuit, and there is an effect that a wide linearity range that cannot be obtained by the diode detection circuit alone can be obtained. In particular, since the level signal of at least one diode detection circuit is limited to a predetermined level or less by the limiter circuit, the slope of the range in which linearity is obtained can be suppressed by only the diode detection circuit. Can be secured.

According to the present invention, the level signal output of each diode detection circuit can be separately amplified by the amplifier. Therefore, by appropriately setting the amplification factor of the amplifier, it is possible to obtain a higher level than when a plurality of diodes are simply added. Has an effect that a wider linearity range can be secured. In this case, in particular, if a limiter circuit for limiting a level signal input to the output circuit to a predetermined level or less is provided between at least one amplifier and the output circuit, linearity is secured from a smaller detection signal. can do.

According to the present invention, at least one of the amplifiers is configured so that its amplification characteristics can be adjusted.
By the above adjustment, matching of the characteristics of the respective detection circuits can be ensured, and there is an effect that a large number of detection circuits having stable characteristics can be obtained even during mass production.

According to the present invention, the rise of the detection signal from around 0 V can be improved by the characteristics of the diode disposed in parallel with the limiter circuit, and a circuit configuration in which the diode detection circuit and the amplifier are combined is provided. There is an effect that a wider linearity range can be secured than in the case.

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 in the same manner 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.

Similarly, if a received signal is detected by using the above-described detection circuit, the accuracy of a received signal having a small signal power to a received signal having a large signal power can be improved as compared with the case of using only one diode detection signal. 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 showing a configuration of a transmitting apparatus according to Embodiment 1 of the present invention.

FIG. 2 is a characteristic diagram of a detection circuit showing an example of characteristics of the detection circuit according to the first embodiment of the present invention;

FIG. 3 is a circuit diagram showing a configuration of a receiving device according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a transmitting apparatus according to Embodiment 3 of the present invention.

FIG. 5 is a characteristic diagram of a detection circuit illustrating a characteristic example of the detection circuit according to the third embodiment of the present invention;

FIG. 6 is a circuit diagram showing a configuration of a transmitting apparatus according to Embodiment 4 of the present invention.

FIG. 7 is a characteristic diagram of a detection circuit showing input / output characteristics when two amplification rate setting resistors are appropriately adjusted in the detection circuit according to Embodiment 4 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.

Claims (8)

[Claims] A plurality of diode detection circuits receiving an input signal and outputting a level signal corresponding to the signal power, and an output outputting a detection signal having a level corresponding to a sum of powers of the plurality of level signals And a detection circuit comprising: 2. A limiter circuit is provided between at least one diode detection circuit and an output circuit for limiting a level signal input to the output circuit to a predetermined level or less. Item 2. The detection circuit according to Item 1. 3. A plurality of diode detection circuits for outputting a level signal corresponding to the input signal power, an output circuit for outputting a detection signal having a level corresponding to the sum of the power of the plurality of level signals, and each diode detection circuit A detection circuit, comprising: one or more amplifiers disposed in a level signal transmission path between a circuit and an output circuit, and amplifying the level of a level signal. 4. The at least one amplifier is configured so that its amplification characteristic is adjustable.
Detection circuit as described. 5. A limiter circuit is provided between at least one amplifier and an output circuit for limiting a level signal input to the output circuit to a predetermined level or less. Alternatively, the detection circuit according to claim 4. 6. The detection circuit according to claim 5, wherein a diode is arranged in parallel with at least one limiter circuit. 7. A transmission circuit that outputs a transmission signal, a transmission signal amplification circuit that receives the transmission signal, amplifies the transmission signal and outputs an amplified transmission signal, and divides the amplified transmission signal into two. 4. A detection circuit according to claim 1, wherein one of said distribution transmission signals is input and outputs a detection signal having a level corresponding to the signal power. A transmission device, comprising: a power control circuit that controls an amplification factor of the transmission signal amplification circuit according to a signal level; and a transmission antenna that outputs the other of the divided transmission signals. 8. A receiving antenna for outputting a received signal corresponding to a received radio wave, a distribution circuit for dividing the received signal into two and outputting a distributed received signal, and one of the distributed received signals is inputted, 4. The detection circuit according to claim 1 or 3, wherein the detection circuit outputs a detection signal having a level corresponding to the signal power, and a reception state is determined based on the level of the detection signal, and a reception determination that outputs a predetermined reception detection signal. And a circuit.