JP2011091644A - High frequency device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high frequency device which acquires branch signals, the frequency dependence of which is small over a wide band. <P>SOLUTION: The high frequency device has a directional coupler in which some part of a main line 1 and some part of a branch line 2 are electromagnetically coupled, and a frequency corrector (an attenuator 4 and an equalizer 5) which corrects the frequency characteristics of high frequency signals over a specified wide band, which are extracted from some part of the main line 1 by the directional coupler and transmitted from some part of the branch line 2, so as to reduce the frequency dependence over the specified wide band. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a high-frequency device that processes a high-frequency signal, and particularly to a high-frequency device including a directional coupler.

  Some high-frequency devices that process high-frequency signals include a directional coupler that branches high-frequency signals. As a directional coupler for branching a high-frequency signal, for example, a directional coupler using a balun is commonly used. However, in a directional coupler using a balun, when the high-frequency signal to be handled is at a high level, the balun core may be magnetized, resulting in distortion and spurious. In addition, the balun has the problem that the winding variation when winding the winding around the core greatly affects the characteristics of the balun, and the problem that the balun characteristics become unstable as the frequency of the high-frequency signal to be handled increases. Yes.

  On the other hand, a directional coupler having a configuration in which a part of a main line and a part of a branch line are electromagnetically coupled is also commonly used (see, for example, Patent Document 1 and Patent Document 2). In a directional coupler having a configuration in which a part of a main line and a part of a branch line are electromagnetically coupled, a part of the branch line has a length of 1/4 wavelength of a desired frequency, and a part of the main line And a part of the branch line are arranged close to each other in parallel and are electromagnetically coupled. Thereby, a part of the branch line functions as an antenna for the high-frequency signal of the desired frequency, and a part of the high-frequency signal of the desired frequency is extracted from the main line to the branch line.

Japanese Unexamined Patent Publication No. 2009-27617 (FIG. 12) Japanese Patent Laying-Open No. 2006-211199 (FIG. 6)

  When the branch signal has a narrow band, there is no problem if the desired frequency is set to the frequency of the branch signal. However, when the branch signal has a wide band, there is a problem that the frequency dependency of the branch signal is increased even if the desired frequency is set to any frequency within the band of the branch signal.

  In view of the above situation, an object of the present invention is to provide a high-frequency device capable of obtaining a branch signal having a small frequency dependency over a wide band.

  In order to achieve the above object, a high-frequency device according to the present invention includes a directional coupler in which a part of a main line and a part of a branch line are electromagnetically coupled, and the main line by the directional coupler. And a frequency correction unit that corrects the frequency characteristics of a predetermined broadband high-frequency signal extracted from a part of the branch line and transmitted from a part of the branch line so that frequency dependence is reduced over the predetermined broadband. .

  A configuration example of the frequency correction unit includes a configuration having an equalizer and an attenuator.

  From the viewpoint of reducing the size of the directional coupler, it is preferable that a part of the branch line has a length of ¼ wavelength of the predetermined broadband upper limit frequency. However, if a part of the branch line has a length of ¼ wavelength of the upper limit frequency of the predetermined wide band due to the predetermined wide band range or the branch side frequency characteristic of the directional coupler, the predetermined wide band In some cases, the coupling loss between terminals at the lower limit frequency becomes larger than the desired coupling loss between terminals. Therefore, when a part of the branch line is made a length of ¼ wavelength of the predetermined broadband upper limit frequency, the inter-terminal coupling loss at the predetermined broadband lower limit frequency is larger than the desired inter-terminal coupling loss. In such a case, it is desirable that a part of the branch line has a length of a quarter wavelength of a frequency lower than the predetermined upper limit frequency of the wide band. As a result, the inter-terminal coupling loss at the lower limit frequency of the predetermined wide band can be made to be substantially the same level as the inter-terminal coupling loss at the upper limit frequency.

  According to the high frequency device of the present invention, a directional coupler in which a part of the main line and a part of the branch line are electromagnetically coupled, and the directional coupler is extracted from a part of the main line. The frequency correction unit includes a frequency correction unit that corrects the frequency characteristics of a predetermined wide-band high-frequency signal transmitted from a part of the branch line so that frequency dependence is reduced over the predetermined wide-band. The frequency dependence of the signal output from the signal, that is, the branched signal is reduced over the predetermined wide band.

It is a figure which shows the schematic structural example of RF transmitter which concerns on one Embodiment of this invention. It is a figure which shows the insertion loss between input-output in the output terminal of RF transmitter shown in FIG. It is a figure which shows the branch side frequency characteristic of the directional coupler of RF transmitter shown in FIG. It is a figure which shows the coupling loss between terminals in the monitor terminal of RF transmitter shown in FIG. It is a figure which shows the schematic structural example of RF amplifier which concerns on one Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention can be applied to all high-frequency devices that process high-frequency signals. Here, the present invention is applied to an RF transmitter that is an example of the high-frequency device, and an RF amplifier that is another example of the high-frequency device. The case where the present invention is applied to will be described as an example.

  First, a case where the present invention is applied to an RF transmitter that is an example of a high-frequency device will be described. FIG. 1 shows a schematic configuration example of an RF transmitter according to an embodiment of the present invention. An RF transmitter according to an embodiment of the present invention shown in FIG. 1 includes a directional coupler having a configuration in which a part 1 of a trunk line and a part 2 of a branch line are electromagnetically coupled, and a termination resistor 3. An attenuator 4, an equalizer 5, an output terminal T 1, a monitor terminal T 2, an input signal processing circuit 6, an amplifier 7, a bandpass filter 8, and an isolator 9. . In the present embodiment, the main line and the branch line are each composed of a microstrip line.

  The input signal processing circuit 6 processes an input signal (for example, an RF signal or an optical signal) and outputs an RF signal obtained as a result of the signal processing to the main line. In the main line, an amplifier 7, a band pass filter 8, and an isolator 9 are provided in this order from the input signal processing circuit 6 side. An output terminal T1 is provided at the end of the main line. The RF signal output from the input signal processing circuit 6 is amplified by the amplifier 7, band-limited by the band-pass filter 8, passes through the isolator 9, and is output from the output terminal T1. The isolator 9 passes the signal in the forward direction (the direction from the input signal processing circuit 6 toward the output terminal T1) as described above, but blocks the signal in the reverse direction.

  As described above, a part 1 of the main line that is a part of the line between the isolator 9 and the output terminal T1 is electromagnetically coupled to the part 2 of the branch line, and the direction along with the part 2 of the branch line. It constitutes a sex coupler.

  One end of the termination resistor 3 is connected to the end of the branch line 2 on the same side as the output terminal T1, and the other end of the termination resistor 3 is grounded. The resistance value of the terminating resistor 3 is matched to the impedance of the output terminal T1. The remaining part of the branch line extends from the end of the part 2 of the branch line opposite to the output terminal T1, and the remaining part of the branch line includes an attenuator 4 and an equalizer 5 in order from the part 2 side of the branch line. Is provided. A monitor terminal T2 is provided at the end of the branch line.

  Here, an example of setting related to the part 2 of the branch line, the attenuator 4, and the equalizer 5 will be described.

  A part 2 of the branch line is set to a length of a quarter wavelength of a predetermined broadband upper limit frequency. Accordingly, the predetermined wideband RF signal extracted from the part 1 of the main line and transmitted from the part 2 of the branch line to the attenuator 4 has a small inter-terminal coupling loss at a predetermined wideband upper limit frequency, and a predetermined wideband RF signal. The coupling loss between terminals is large at the lower limit frequency. Thus, the predetermined broadband RF signal extracted from the main line and transmitted from the part 2 of the branch line to the attenuator 4 has a large frequency dependency.

  Subsequently, the attenuator 4 is connected to the trunk line so that the inter-terminal coupling loss at the predetermined wide-band lower limit frequency in the predetermined wide-band RF signal output from the attenuator 4 approaches the desired inter-terminal coupling loss at the monitor terminal T2. A predetermined broadband RF signal extracted from the part 1 of the line and transmitted from the part 2 of the branch line to the attenuator 4 is uniformly attenuated. Thereby, in the predetermined wide band RF signal output from the attenuator 4, the inter-terminal coupling loss at the predetermined lower limit frequency of the wide band is substantially equal to the desired inter-terminal coupling loss at the monitor terminal T2. The inter-terminal coupling loss at the upper limit frequency does not reach the desired inter-terminal coupling loss at the monitor terminal T2.

  Subsequently, in the predetermined broadband RF signal output from the equalizer 5, the inter-terminal coupling loss at the predetermined broadband lower limit frequency is as small as possible, and the frequency characteristics in the equalizer 5 are opposite to the branch side frequency characteristics of the directional coupler. The equalizer 5 corrects the frequency characteristic of a predetermined broadband RF signal output from the attenuator 4 so as to obtain the characteristic. As a result, in the predetermined wideband RF signal output from the equalizer 5 and transmitted to the monitor output terminal T2, that is, the predetermined wideband branch signal, the frequency dependence is small over the predetermined wideband and is almost equal to the desired inter-terminal coupling loss. Become.

  As described above, a part 2 of the branch line, the attenuator 4 and the equalizer 5 are set, the predetermined wide band upper limit frequency is, for example, 770 MHz, the predetermined wide band lower limit frequency is, for example, 470 MHz, and the desired terminal at the monitor terminal T2 When the coupling loss is -30 dB, the insertion loss between the input and output at the output terminal T1 is almost 0 dB as shown in FIG. 2, and the branch side frequency characteristic of the directional coupler is predetermined as shown in FIG. 4 has a large frequency dependence, whereas the inter-terminal coupling loss at the monitor terminal T2 is a desired inter-terminal coupling loss over a predetermined wide band with a small frequency dependence as shown in FIG. It almost coincides with −30 dB. In the case where the attenuator 4 and the equalizer 5 which are characteristic parts of the present invention are not provided, the inter-terminal coupling loss at the monitor terminal T2 becomes as shown in FIG. 3, and the inter-terminal coupling at the monitor terminal T2 The loss has a large frequency dependency over a predetermined wide band. The frequency characteristics of the trunk line output are flat over a wide band, and when the frequency characteristics are confirmed with a measuring instrument or the like at the monitor terminal T2, the frequency characteristic at the branch output is also made flat so that an accurate level over the wide band is obtained. Can measure.

  Further, as described above, the length of the part 2 of the branch line can be shortened by setting the length 2 of the part 2 of the branch line to ¼ wavelength of the predetermined broadband upper limit frequency. The size of the coupler can be reduced. However, if a part of the branch line 2 has a length of 1/4 wavelength of the upper limit frequency of the predetermined wide band due to the predetermined wide band range and the branch side frequency characteristics of the directional coupler, the predetermined lower limit frequency of the wide band is obtained. May be larger than the desired inter-terminal coupling loss at the monitor terminal T2. Therefore, when a part 2 of the branch line has a length of ¼ wavelength of the predetermined wideband upper limit frequency, the interterminal coupling loss at the predetermined wideband lower limit frequency becomes the desired interterminal coupling loss at the monitor terminal T2. In such a case, the length 2 of the branch line 2 is set to a quarter wavelength of a frequency lower than a predetermined broadband upper limit frequency (for example, a center frequency 620 MHz from 470 MHz to 770 MHz). It is preferable that the inter-terminal coupling loss at the lower limit frequency in a wide band should not be larger than the desired inter-terminal coupling loss at the monitor terminal T2.

  Next, a case where the present invention is applied to an RF amplifier which is another example of the high-frequency device will be described. FIG. 5 shows a schematic configuration example of an RF amplifier according to another embodiment of the present invention. 5 that are the same as those in FIG. 1 are denoted by the same reference numerals.

  An RF amplifier according to an embodiment of the present invention shown in FIG. 5 includes a directional coupler having a configuration in which a part 1 of a main line and a part 2 of a branch line are electromagnetically coupled, a termination resistor 3, , An attenuator 4, an equalizer 5, an output terminal T 1, a monitor terminal T 2, amplifiers 10 and 11, and a mixer 12 that mixes and outputs the output signal of the amplifier 10 and the output signal of the amplifier 11. .

  The amplifier 10 receives a first band RF signal (for example, a UHF band signal or a VHF band High channel signal), and the amplifier 11 receives a second band RF signal (for example, a VHF band signal or VHF band Low channel signal, etc.) are input. Therefore, the signal output from the mixer 12 is an RF signal in a first band and a second band (a predetermined wide band RF signal).

  Since the configuration subsequent to the mixer 12 and the operation at that portion are the same as those after the isolator 9 of the RF transmitter according to the embodiment of the present invention shown in FIG.

  As mentioned above, although embodiment which concerns on this invention was described, the range of this invention is not limited to this, A various change can be added and implemented in the range which does not deviate from the main point of invention.

  For example, the same effect can be obtained even if the arrangement of the attenuator 4 and the equalizer 5 is switched.

  The attenuator 4 also plays a role of adjusting the impedance on the branch line side. However, the impedance on the branch line side can be set to a desired value without providing the attenuator 4, and the equalizer 5 When having a frequency characteristic that also functions as an attenuation, the attenuator 4 can be removed.

  Further, in this embodiment, the signal passing through the main line side of the directional coupler was the output signal of the high frequency device, but the signal passing through the main line side of the directional coupler is another high frequency signal (for example, High-frequency equipment input signal).

  In the present embodiment, the high-frequency signal extracted from the main line side of the directional coupler to the branch line side and then processed by the attenuator 4 and the equalizer 5 is output to the monitor terminal T2. Instead of being output, it may be used for other signal processing.

DESCRIPTION OF SYMBOLS 1 Part of trunk line 2 Part of branch line 3 Terminating resistance 4 Attenuator 5 Equalizer 6 Input signal processing circuit 7 Amplifier 8 Band pass filter 9 Isolator 10, 11 Amplifier 12 Mixer T1 Output terminal T2 Monitor terminal

Claims (4)

A directional coupler in which a part of the main line and a part of the branch line are electromagnetically coupled;
The frequency characteristic of a predetermined wide-band high-frequency signal extracted from a part of the trunk line by the directional coupler and transmitted from a part of the branch line is corrected so that the frequency dependence is reduced over the predetermined wide band. A high frequency device comprising a frequency correction unit.   The high frequency device according to claim 1, wherein the frequency correction unit includes an equalizer and an attenuator.   3. The high-frequency device according to claim 1, wherein a part of the branch line has a length of ¼ wavelength of the predetermined broadband upper limit frequency.   3. The high-frequency device according to claim 1, wherein a part of the branch line has a length of ¼ wavelength of a frequency lower than the predetermined broadband upper limit frequency.

Images