JP5904145B2 - Power monitor circuit - Google Patents

Description

  The present invention relates to a power monitor circuit that measures the output of a power amplifier.

  In a power amplifier that performs power amplification of RF (Radio Frequency) band high frequency signals (hereinafter referred to as RF signals) such as microwaves and millimeter waves, the output side of the power amplifier is used to control the output power of the power amplifier or detect an abnormality. Is provided with a power monitor circuit. The power monitor circuit includes a distribution circuit for branching the power of the RF signal output from the power amplifier, and a detection circuit that outputs a DC voltage according to the output of the RF signal branched by the distribution circuit. The power monitor circuit can measure the output power of the power amplifier by measuring the output voltage of the detection circuit.

  In order to increase the measurement accuracy of the output power measured by the power monitor circuit, the power monitor circuit is disposed near the power amplifier. In the power monitor circuit, a minute power of 1/100 to 1/10000 of the power output from the power amplifier is detected, so that the power detection accuracy deteriorates due to interference from the main line and peripheral circuits through which the high power passes. There is a problem. Therefore, it is possible to prevent interference with the detection circuit by separating the storage container (chassis) for storing the detection circuit and the power amplifier, or by partitioning with a metal wall to electromagnetically shield the detection circuit and the amplifier. Done. However, this causes a problem that the chassis structure becomes complicated and large.

Here, various conventional examples will be further described.
As a conventional example 1, FIG. 7 is a diagram showing a configuration of a power amplifier having a built-in power monitor circuit having a structure in which a detection circuit is shielded by a metal wall. In the figure, a power amplifier incorporating a power monitor circuit includes an amplifier 13 that performs power amplification, a distributor 14 that distributes the output power of the amplifier 13, and a detector that detects the output power of the amplifier 13 distributed by the distributor 14. The circuit 15 and the chassis 12 are included. The chassis 12 is provided with an input terminal 10 and an output terminal 11, a detection output terminal 16, and a metal wall 17. The metal wall 17 constitutes a partition wall that partitions the detection circuit 15 and the main line connected to the output side of the amplifier 13, and shields electromagnetic interference. In the detection circuit of FIG. 7, the signal input from the input terminal 10 is amplified by the amplifier 13 and then guided to the output terminal 11. A part of the signal amplified by the amplifier 13 is distributed by the distributor 14, detected by the detection circuit 15, and guided to the detection output terminal 16. The detection output terminal 16 is connected to the detection circuit 15 through a through terminal.

  Next, as a conventional example 2, Patent Document 1 discloses a conventional high-frequency power detection circuit (corresponding to a power monitor circuit). As shown in FIG. 3 of Patent Document 1, a conventional high-frequency power detection circuit includes a printed circuit board, a stripline circuit, a detection stripline circuit, a termination resistor, a detection circuit, and a low-pass filtering. (Hereinafter referred to as LPF; low-pass filter) and a feedthrough capacitor. The feedthrough capacitor constitutes a feedthrough terminal to an external circuit. Next, the operation will be described. The RF signal input to the stripline circuit is branched by the detection stripline circuit and guided to the detection circuit. The signal detected by the detection circuit is output through the feedthrough capacitor after the leakage of the RF signal is prevented by the LPF.

  Similarly, Patent Document 1 discloses a conventional high-frequency power detection circuit (corresponding to a power monitor circuit) as Conventional Example 3. As shown in FIG. 1 of Patent Document 1, a conventional high-frequency power detection circuit includes a printed circuit board, a stripline circuit, a detection stripline circuit, a termination resistor, a detection circuit, and an optical signal converter. And an optical fiber cable and a second printed circuit board. The operation of this circuit is substantially the same as that of Conventional Example 2, except that the detection signal detected by the detection circuit is converted into an optical signal by an optical signal converter and output to the outside by an optical fiber cable.

JP-A-5-63401

  The power monitor circuit of Conventional Example 1 (FIG. 7) is shielded from the main line by a metal wall, and has an advantage that interference can be greatly reduced. However, there are problems such as complication and enlargement of the storage container (chassis) structure described above.

  The high-frequency power detection circuit (corresponding to the power monitor circuit) of Conventional Example 2 (FIG. 3 of Patent Document 1) has no metal wall separating the main line and the power monitor circuit, and thus the storage container (chassis) structure is simplified. There are advantages you can do. Further, since the main line and the power monitor circuit are not separated, there is an advantage that the circuit can be configured with a single substrate. Further, since the LPF is formed in the direction from the detection circuit to the through terminal, there is an advantage that the RF signal is not easily leaked from the detection output terminal. However, since the detection circuit and the main line through which high power passes are in the same space, the output line connecting the through terminal and the detection circuit serves as an antenna, and the RF signal radiated from the main line to the space is detected by the detection circuit. There is a problem that the detection accuracy is lowered.

  The high-frequency power detection circuit (corresponding to a power monitor circuit) of Conventional Example 3 (FIG. 1 of Patent Document 1) has the same chassis structure as Conventional Example 2, and further converts the detection output into an optical signal to convert the antenna into There is an advantage that the line that operates as can be deleted. As a result, it is possible to prevent a decrease in detection accuracy due to interference with the output line of the detection circuit, which was a problem in the conventional example 2. However, there is a problem that a circuit for converting an electric signal into light is required, and the circuit configuration becomes large and complicated. Further, in an external gain control circuit or output power control circuit to which a detection output is guided, there is a problem that the configuration of the external circuit becomes complicated because the optical signal must be converted back into an electrical signal.

  The present invention has been made to solve the above-described problem, and does not complicate the structure of the storage container of the power monitor circuit, and by interference of the RF signal radiated from the main line into the space to the detection circuit. An object is to suppress deterioration of detection accuracy.

  A power monitoring circuit according to the present invention includes a distribution circuit that distributes power of a main line that transmits high-frequency power to a sub-line, a detection diode connected to the sub-line of the distribution circuit, and one end connected to the detection diode. A low-pass filter whose cutoff frequency is lower than the frequency of the signal passing through the main line and blocking the high-frequency of the signal passing from both directions in the one end side direction and the other end side direction, and the low pass filter A detection output terminal connected to the end side via a connection line and a through terminal; and a detection circuit for detecting a signal distributed from the distribution circuit; and the distribution circuit and the detection circuit are accommodated, and And a storage container through which the through terminal penetrates inside and outside.

  According to the present invention, a bidirectional low-pass filter including at least one type of resistor or inductor and a capacitor is provided on the line connecting the penetration terminal to the outside of the storage container and the detection circuit. A low-pass filter can be formed in any direction from the direction and the through terminal to the detection circuit direction. As a result, leakage of the high frequency signal to the outside of the storage container can be prevented, and interference of the high frequency signal to the detection circuit via the line can be suppressed. As a result, a highly accurate power monitor circuit can be configured with a storage container having a simpler structure.

FIG. 3 is a diagram showing a configuration of a power amplifier incorporating a power monitor circuit according to the first embodiment. FIG. 3 is a diagram showing a configuration of a power monitor circuit according to the first embodiment. It is a figure which shows the structure of the electric power monitor circuit which has a detection circuit with which the diode was connected in parallel. It is a figure which shows the detection voltage calculation result of the power monitor circuit to which the bidirectional | two-way LPF which consists of resistance and a capacitor, and the unidirectional LPF is applied. It is a figure which shows the detection voltage calculation result of the power monitor circuit to which the bidirectional LPF which consists of an inductor and a capacitor, and the unidirectional LPF is applied. FIG. 6 is a diagram illustrating a configuration of a power monitor circuit according to a second embodiment. It is a figure which shows the structure of the power amplifier which incorporated the conventional power monitor circuit.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a power amplifier incorporating a power monitor circuit according to Embodiment 1 of the present invention. FIG. 2 is a diagram showing a configuration of the power monitor circuit according to the first embodiment. In FIG. 1, a power amplifier incorporating a power monitor circuit includes an amplifier 13 that performs power amplification, a directional coupler 32, a detection circuit 23 that detects output power of the amplifier 13, and a chassis 100. The directional coupler 32 is connected to the subsequent stage of the amplifier 13 between the input terminal 20 and the output terminal 21. The directional coupler 32 constitutes a distribution circuit that distributes the output power of the amplifier 13, and distributes the power of a main line 32a (described later) that transmits high-frequency power. The detection circuit 23 is connected to the directional coupler 32 so as to detect the output power of the amplifier 13 distributed by the directional coupler 32. The directional coupler 32 and the detection circuit 23 are configured on the same wiring board 35. The wiring board 35 is composed of a printed wiring board or a ceramic wiring board.

  The chassis 100 is a storage container formed of a metal or a dielectric multilayer substrate made of, for example, ceramic whose outer periphery is covered with a metal conductor, and having a conductive surface grounded on the outer periphery. The chassis 100 houses the amplifier 13, the directional coupler 32, and the detection circuit 23, and constitutes a storage container that is electromagnetically shielded so as to prevent electromagnetic interference with the outside. The chassis 100 is provided with an input terminal 20, an output terminal 21, and a detection output terminal 24. The detection output terminal 24 is connected to a penetration terminal 28 provided so as to penetrate the inside and outside of the chassis 100, and is connected to the detection circuit 23 via the penetration terminal 28. The feedthrough terminal 28 constitutes a feedthrough capacitor for high frequency short circuit having a capacitance C2.

  A desired RF signal input from the input terminal 20 is amplified by the amplifier 13 and then guided to the output terminal 21. A part of the signal amplified by the amplifier 13 is distributed by the directional coupler 32 and then detected by the detection circuit 23. Further, the signal detected by the detection circuit 23 is guided to the detection output terminal 24 via the through terminal 28.

  In FIG. 2, the power monitor circuit 42 according to the first embodiment includes a detection circuit 23, a detection output terminal 24, and a directional coupler 32. The directional coupler 32 includes a main line 32a and a sub line 32b. The sub line 32b of the directional coupler 32 has a predetermined length (for example, a length that is a quarter of an odd multiple of the wavelength λ indicating the electrical length of the desired RF signal). Separated from the main line 32a (for example, with a gap sufficiently shorter than a quarter of the wavelength λ indicating the electrical length of the desired RF signal) and coupled to the electric field of the main line 32a To do. The main line 32a and the sub line 32b of the directional coupler 32 are configured by a high-frequency transmission line including a distributed constant line such as a microstrip line or a triplate line. The main line 32 a of the directional coupler 32 is connected between the input terminal 20 and the output terminal 21. The sub line 32b of the directional coupler 32 has one end connected to the detection circuit 23 and the other end connected to one end of a termination resistor 22 having a resistance value R2. The other end of the termination resistor 22 is grounded. The output power of the amplifier 13 passes through the main line 32 a of the directional coupler 32, and a part of the passing power is coupled to the sub line 32 b and guided to the detection circuit 23. The power flowing through the sub line 32 b of the directional coupler 32 is not coupled to the main line 32 a of the directional coupler 32.

  The detection circuit 23 includes a detection diode 25, a resistor 26 having a resistance value R2, a resistor 27 having a resistance value R3, a capacitor 31 having a capacitance C2, and a capacitor 30 having a capacitance C1. The The anode of the detection diode 25 is grounded. One end of the sub line 32 b of the directional coupler 32 is connected to the cathode of the detection diode 25 in the detection circuit 23. The cathode of the detection diode 25 is connected in parallel to one end of the resistor 26. The other end of the resistor 26 is connected in series to one end of the resistor 27. The other end of the resistor 27 is connected in series to a through terminal 28 outside the detection circuit 23. That is, one end of the sub line 32b of the directional coupler 32 is connected in series to the resistors 26 and 27, and the detection diode 25 is connected in parallel to one end of the sub line 32b of the directional coupler 32. It becomes. The capacitor 31 is connected between the other end of the resistor 26 and the ground, and is connected in parallel with the series circuit of the resistors 26 and 27. The capacitor 30 is connected between the other end of the resistor 27 and the ground, and is connected in parallel with the series circuit of the resistors 26 and 27. The resistors 26 and 27 apply a bias voltage to the detection diode 25. The capacitor 30 forms a unidirectional LPF. The resistors 26 and 27 and the capacitor 31 constitute a T-type bidirectional LPF 39. The bidirectional LPF 39 constitutes a filter circuit that blocks at least a desired RF signal amplified and output by the amplifier 13 and harmonics of the RF signal.

  The connection line 33 is a line that connects the high-frequency short-circuit feedthrough capacitor constituting the feedthrough terminal 28 and the detection circuit 23. The high frequency short-circuit feedthrough capacitor constituting the feedthrough terminal 28 is connected in parallel to the connection point of the series circuit of the detection output terminal 24 and the current source 29.

Next, the operation of the power monitor circuit 42 of the first embodiment will be described.
The RF signal input to the amplifier 13 from the input terminal 20 is amplified to a required output power by the amplifier 13. The RF signal input from the input terminal 20 and amplified by the amplifier 13 is guided to the output terminal 21 via the main line 32 a of the directional coupler 32. Further, a part of minute power that is 1/100 to 1/10000 of the input power of the RF signal input to the main line 32a of the directional coupler 32 is guided to the detection circuit 23 via the sub line 32b. Terminate with a termination resistor 22. A part of the RF signal guided to the detection circuit 23 via the sub line 32b is detected by the detection diode 25, and the DC resistance of the detection diode 25 is changed according to the electric power. The output voltage Vp of the detection output terminal 24 changes according to the change of the DC resistance of the detection diode 25, and the output power of the amplifier 13 can be measured from the output voltage Vp.

In addition, a bidirectional LPF 39 including resistors 26 and 27 and a capacitor (capacitor) 31 is provided for the connection line 33 that connects the through terminal 28 and the detection circuit 23, so that the direction on the same wiring board 35 or through the space. Leakage of the RF signal from the sex coupler 32 and the detection circuit 23 toward the through terminal 28 can be prevented. Further, by providing the bidirectional LPF 39, it is possible to suppress interference of the external RF signal input from the through terminal 28 and the connection line 33 to the detection circuit 23. That is, the bi-directional LPF 39 has a characteristic that cuts off a high frequency even if a signal is input from either the input side or the output side of the detection circuit 23. Here, the cutoff frequency of the bidirectional LPF 39 is set to a value lower than the frequency f _{0 of the} RF signal passing through the directional coupler as shown in Equation 1. That is, the cutoff frequency of the bidirectional LPF 39 is set to be lower than the frequency of the signal passing through the main line 32 a of the directional coupler 32.

  Here, in order to confirm the effectiveness of the power monitor circuit 42 according to the first embodiment, the detection voltage of both the bidirectional LPF 39 including the resistors 26 and 27 and the capacitor 31 and the power monitor circuit to which the unidirectional LPF is applied was calculated. This will be described below. FIG. 3 is a comparison diagram showing the configuration of the power monitor circuit 45 using only the unidirectional LPF. The power monitor circuit 45 shown in FIG. 3 is different from the power monitor circuit 45 shown in FIG. 1 in that the bidirectional LPF 39 shown in FIG. 1 is not provided and the resistor 26 and the capacitor 31 shown in FIG. The power monitor circuit 45 of FIG. 3 has a function equivalent to that of the detection circuit of the conventional example 2 shown in FIG.

  In the conventional power monitor circuit shown in FIG. 3 of Patent Document 1, a diode is connected in series with the output of the directional coupler, and the detection voltage of the RF signal is directly used. On the other hand, the power monitor circuit 45 shown in FIG. 3 of the comparative example is different in that a detection diode is connected in parallel and a change in DC resistance of the detection diode according to input power is used. However, there is no significant difference between the basic operations of the two, and the function of the power monitor circuit 45 of FIG. 3 of the comparative example using the unidirectional LPF can be regarded as equivalent to that of the conventional example 2. Therefore, here, the effectiveness of the power monitor circuit 42 of the first embodiment shown in FIG. 2 will be described using FIG. 3 as a comparative example.

  FIG. 4 is a diagram showing calculation results for the detection voltage of the power monitor circuit 42 of FIG. 2 according to the first embodiment and the detection voltage of the power monitor circuit 45 of FIG. 3 of the comparative example. 3 shows a calculation result by the power monitor circuit 45 of FIG. 3 that does not have a directional LPF, and (b) shows a calculation result by the power monitor circuit 42 of FIG. Table 1 shows the calculation conditions of FIG.

  Since the phase of the interference wave strongly depends on the shape of the casing, the calculation was performed by changing the phase. At this time, the resistance component R3 in FIG. 3 is set to 800Ω, and is constant with the combined resistance component (R2 + R3) of the resistors 26 and 27 in FIG. As is clear from the calculation result shown in FIG. 4, by providing the bidirectional LPF 39 according to the first embodiment, the change in the detection voltage with respect to the phase change is suppressed as shown in FIG. It can be confirmed that the interference to the detection circuit 23 via can be reduced. On the other hand, when the bidirectional LPF 39 is not provided, it can be seen that the detection voltage changes according to the phase change as shown in FIG.

  As described above, by using the power monitor circuit 42 according to the first embodiment, it is possible to reduce interference from the main line through the connection line 33 that connects the through terminal 33 and the detection circuit 23, so that the chassis 100 is made of metal. It is not necessary to provide a partition wall (metal wall 17 in FIG. 7), and the chassis structure can be simplified.

  In the above description, the bidirectional LPF 39 is configured with two resistors and one capacitor. However, another bidirectional LPF in which the resistors 26 and 27 are replaced with two inductors may be configured. FIG. 5 is a diagram showing a calculation result of a detection voltage of a power monitor circuit to which a bidirectional LPF composed of two inductors and one capacitor replacing the resistors 26 and 27 and a unidirectional LPF is applied, and FIG. 3 shows the calculation result by the power monitor circuit corresponding to FIG. 3 without the directional LPF, and FIG. 5B shows the calculation result by the power monitor circuit having the bidirectional LPF in which the resistors 26 and 27 in FIG. 2 are replaced with inductors. . In the power monitor circuit corresponding to FIG. 3 without the bidirectional LPF of FIG. 5A, the resistor 27 of FIG. 3 is replaced with an inductor. Table 2 shows the calculation conditions of FIG.

  In Table 2, L2 is an inductance value when the resistor 26 (R2) is replaced with an inductor, and L3 is an inductance value when the resistor 27 (R3) is replaced with an inductor. In addition, the inductor L3 in FIG. 5A is set to 20 nH so that the inductor is constant like the combined inductor (L2 + L3) in FIG.

  As is apparent from the calculation results of FIG. 5, it can be seen that even when an inductor is used, interference through the line can be reduced. Here, the cutoff frequency of the LPF when the inductor is used is expressed as shown in Equation 2. The cutoff frequency of the LPF is set to be lower than the frequency of the signal passing through the main line 32a of the directional coupler 32.

  Note that the inductor and the capacitor may be composed of a distributed constant line such as a microstrip line or an open stub.

  In Embodiment 1, the example in which the bidirectional LPF 39 is configured using the T-type LPF in FIG. 2 has been described. However, the same effect can be obtained even if the bidirectional LPF is configured using the π-type LPF. Can do. The π-type LPF is composed of one resistor (R2) and two capacitors (C2, C2) connected in parallel to both ends of the resistor. Alternatively, the π-type LPF may be composed of one inductor (L2) and two capacitors (C2, C2) connected in parallel to both ends of the inductor.

  In the first embodiment, the detection diode 25 is connected in parallel to the output of the directional coupler 32, but may be connected in series as in Conventional Example 2. Further, in order to further suppress direct interference with the detection diode 25 through the space, a radio wave absorber that causes a loss in the RF signal radiated from the main line to the space is disposed in the vicinity of the detection circuit 23 and in the vicinity thereof. You may do it.

  As described above, the power monitor circuit 42 according to the first embodiment includes the directional coupler 32 that is a distribution circuit that distributes the power of the main line 32a that transmits high-frequency power to the sub-line 32b, and the sub-line of the distribution circuit. The detection diode 25 connected to 32b, one end side is connected to the detection diode 25, the cut-off frequency is lower than the frequency of the signal passing through the main line 32a, and both in the one end side direction and the other end side direction. A bidirectional LPF (low-pass filter) 39 that cuts off a high frequency of a signal passing from the direction, and a detection output terminal 24 connected to the other end of the bidirectional LPF 39 via a connection line 33 and a through terminal 28, And a detection circuit 23 for detecting a signal distributed from the distribution circuit, and the distribution circuit and the detection circuit 23. Container to penetrate (chassis 100), characterized by comprising a. The distribution circuit and the detection circuit 23 are configured on the same wiring board 35.

  The bidirectional LPF 39 has two resistors (R1, R2) or inductors (R1, R2) connected in series, and one capacitor (C2) connected in parallel at the connection point, thereby providing a T-type low-pass filter. It is composed.

  Further, the bidirectional LPF 39 may constitute a π-type low-pass filter by connecting a capacitor (C2) in parallel to both ends of the resistor R2 or the inductor L2.

  Accordingly, the detection circuit 23 is provided by providing a bidirectional LPF 39 including at least one type of resistor or inductor and a capacitor on the line (connection line 33) connecting the through terminal 28 and the detection circuit 23 to the outside of the storage container. The LPF can be formed in any direction from the through terminal 28 to the through terminal 28 and from the through terminal 28 to the detection circuit 23. Accordingly, it is possible to prevent leakage of the RF signal to the outside of the storage container 100 and to suppress interference of the RF signal with the detection circuit via the line. As a result, a highly accurate power monitor circuit can be configured using a storage container having a simple structure that does not have a metal partition between the amplifier 13 and the detection circuit 23. Cost reduction, downsizing, and ease of manufacture can be achieved.

Embodiment 2. FIG.
In the power monitor circuit 42 shown in the first embodiment, since the detection diode 25 has temperature characteristics, the detection output voltage varies with temperature, and there is a problem that power detection accuracy deteriorates. In the second embodiment, a power monitor circuit with a temperature compensation circuit provided with a temperature compensation circuit in the power monitor circuit 42 of the first embodiment will be described.

  FIG. 6 is a diagram showing a configuration of a power monitor circuit with a temperature compensation circuit according to the second embodiment. In FIG. 6, the power monitor circuit 50 with the temperature compensation circuit according to the second embodiment is different from the temperature detection circuit 40, the output terminal 41 of the temperature detection circuit 40, and the power monitor circuit 42 described in the first embodiment. And an output terminal 44 of a power monitor circuit 50 with a temperature compensation circuit. The temperature detection circuit 40 and the differential circuit 43 constitute a temperature compensation circuit. The temperature detection circuit 40 and the power monitor circuit 42 are configured on the same wiring board (the wiring board 35). In FIG. 6, the same reference numerals as those in FIG. 2 denote the same elements and operate in the same manner.

  The output terminal 41 of the temperature detection circuit 40 is connected to one input terminal of the differential circuit 43. The output terminal 24 of the power monitor circuit 42 is connected to the other input terminal of the differential circuit 43. The output terminal 44 is connected to the output terminal of the differential circuit 43. The temperature detection circuit 40 includes the detection circuit 23, the connection line 33, the through terminal 28, and the current source 29 shown in FIG. 2, and is connected in the same manner. However, unlike FIG. 2, the output terminal 41 in FIG. 6 corresponds to the detection output terminal 24 in FIG.

  Next, the operation of the power monitor circuit 50 with a temperature compensation circuit according to the second embodiment will be described. The power applied to the input terminal 20 changes the voltage at the output terminal 24 of the power monitor circuit 42 according to the first embodiment in accordance with the input power.

  On the other hand, the temperature detection circuit 40 has the same configuration as that of the detection circuit 23 of the first embodiment, but the input terminal 20 and the directional coupler 32 are not connected. For this reason, the output terminal 41 of the temperature detection circuit 40 outputs a constant voltage without depending on the input power of the input terminal 20.

  The differential circuit 43 calculates the voltage difference between the output voltage from the output terminal 41 of the temperature detection circuit 40 and the output voltage from the detection output terminal 24 of the power monitor circuit 50. The differential circuit 43 outputs a voltage corresponding to the calculated voltage difference from the output terminal 44.

  Since the detection diode 25 has temperature characteristics, the detection output voltage changes according to the temperature. However, since the power monitor circuit 50 with a temperature compensation circuit uses the temperature detection circuit 40 composed of a circuit equivalent to the power monitor circuit 42 and the detection circuit 23 according to the first embodiment, the output voltage difference between them is calculated. Thus, the temperature characteristics of the detection diodes 25 possessed by each other are canceled. Thereby, the power detection accuracy with respect to temperature can be improved.

  Further, since the temperature detection circuit 40 also has a connection line 33 that connects the through terminal 28 and the detection circuit 23 similar to those in FIG. 2, the through capacitor and the detection circuit 23 in the through terminal 28 are the same as in the first embodiment. Interference from the main line is received via the connection line 33 connecting the two. For this reason, the temperature detection circuit 40 according to the second embodiment suppresses interference with the detection diode 25 by providing a bidirectional LPF between the detection diodes of the connection line 33 and the temperature detection circuit 44, thereby reducing power. It is possible to prevent a decrease in detection accuracy.

  In order to suppress direct interference with the detection diode 25 via the space, a radio wave absorber that causes a loss in the RF signal radiated from the main line to the space is disposed in the vicinity of the temperature detection circuit 40. Also good.

  13 amplifier, 20 input terminal, 21 output terminal, 22 termination resistor, 23 detection circuit, 24 detection output terminal, 25 detection diode, 26, 27 resistance, 30, 31 capacitor, 28 feedthrough terminal (feedthrough capacitor for high frequency short circuit), 29 current source, 32 directional coupler, 32a main line, 32b sub line, 33 connection line, 35 wiring board, 39 bidirectional LPF (low pass filter), 40 temperature detection circuit, 42 power monitor circuit, 43 differential circuit, 50 Power monitor circuit with temperature compensation circuit, 100 chassis.

Claims (7)

A distribution circuit that distributes the power of the main line transmitting the high-frequency signal to the sub-line;
A detection diode connected to the sub-line of the distribution circuit;
One end side is connected to the detection diode, the cutoff frequency is lower than the frequency of the signal passing through the main line, and the high frequency of the signal passing from both directions in the one end side direction and the other end side direction is cut off. Bidirectional low-pass filter,
And a detection circuit for detecting a signal distributed from the distribution circuit,
A connection line to which the other end of the bidirectional low-pass filter is connected to one end;
One end side is connected to the other end of the connection line, and the other end side is connected to the detection output terminal so as to pass through the inside and outside of the container, and has a through terminal constituting a high frequency short-circuit through capacitor. A storage container for storing the circuit ;
With
The power monitoring circuit , wherein the bidirectional low-pass filter suppresses interference of a high-frequency signal radiated from the main line into the space and guided through the connection line to the detection circuit. A distribution circuit that distributes the power of the main line transmitting the high-frequency signal from the amplifier to the sub-line;
A detection diode connected to the sub-line of the distribution circuit;
One end side is connected to the detection diode, the cutoff frequency is lower than the frequency of the signal passing through the main line, and the high frequency of the signal passing from both directions in the one end side direction and the other end side direction is cut off. Bidirectional low-pass filter,
And a detection circuit for detecting a signal distributed from the distribution circuit,
A connection line to which the other end of the bidirectional low-pass filter is connected to one end;
One end side is connected to the other end of the connection line, and the other end side is connected to the detection output terminal so as to pass through the inside and outside of the container, and has a through terminal constituting a high frequency short-circuit through capacitor. A storage container for storing the circuit ;
With
The power monitoring circuit , wherein the storage container does not have a metal partition between the main line and the detection circuit. 3. The power monitor circuit according to claim 1, wherein the distribution circuit and the detection circuit are configured on the same substrate. The bidirectional low-pass filter, with a resistor or inductor connected two series claims 1 to 3, characterized in that to constitute a T-type low-pass filter by one parallel connection a capacitor to the connection point The power monitor circuit according to any one of the above. 4. The power monitor circuit according to claim 1 , wherein the bidirectional low-pass filter is configured as a π-type low-pass filter by connecting a capacitor in parallel between both ends of a resistor or an inductor. 5. . A temperature detection circuit;
A differential circuit that outputs a voltage corresponding to a voltage difference between the temperature detection circuit and the power monitor circuit according to any one of claims 1 to 5 ;
A power monitor circuit comprising: 6. The power monitor circuit according to claim 5 , wherein the temperature detection circuit comprises a circuit having the same configuration as that of the detection circuit included in the power monitor circuit according to any one of claims 1 to 5.

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