JP4790994B2 - High frequency amplifier - Google Patents

Description

  The present invention relates to a high frequency amplifying apparatus having a distortion detection function for detecting distortion generated in a high frequency amplifier used in, for example, a television broadcast radio wave receiving device or a wireless communication device.

  2. Description of the Related Art Conventionally, in a television receiver or a common television reception system in a general home, when a signal level of a received signal is low, a received signal is amplified using a high-frequency amplifier (booster) (for example, Patent Document 1). reference.).

  In the above high frequency amplification device, when the received signal level to be amplified is high and the output level after amplification exceeds the performance of the amplifier, a distortion component is generated due to nonlinear distortion, and video or audio or digital signal is transmitted to the own channel or another channel. It will interfere. In order to prevent such interference due to the occurrence of distortion, the conventional high-frequency amplification device includes a signal level adjuster so that the level of the input signal can be adjusted.

  FIG. 9 shows a configuration example of a conventional high-frequency amplifier. In FIG. 9, reference numeral 1 denotes an antenna that receives television broadcast radio waves, and a signal received by the antenna 1 is input to the input terminal 3 of the high-frequency amplifier 2. The high-frequency amplifier 2 includes a signal level adjuster 4 and an amplifier 5, and adjusts the signal input to the input terminal 3 by the signal level adjuster 4 and inputs the signal to the amplifier 5. The amplifier 5 amplifies the signal adjusted by the signal level adjuster 4 and outputs the amplified signal to the television receiver from the output terminal 6.

  When the high-frequency amplifier 2 is installed, the operator manually adjusts the signal level adjuster 4 while confirming that there is no interference in the video and audio on the television receiver and confirming the output level.

By manually adjusting the signal level adjuster 4 as described above and setting the level of the output signal of the high frequency amplifying apparatus 2 to an optimum value, generation of distortion components can be prevented.
Japanese Patent No. 3239105

  When adjusting the signal level adjuster 4 in the high frequency amplifying apparatus 2, prepare a measuring instrument (spectrum analyzer or the like) that can check the generated interference wave, or record images such as actual television receivers and measuring instruments. The device must be able to check the audio or signal waveform, bit error rate, etc., and make adjustments while checking the video, audio, signal waveform, and bit error rate.

  However, there are many places where TV receivers are installed on the roof or in high places, and adjustment may be extremely difficult, such as when there is no amplification device nearby that must be adjusted with the equipment to be checked. Many. Furthermore, although the work is often affected by the skill level of the operator, the work of adjusting the output level of the high-frequency amplification device 2 in television reception is one of the important work.

  The present invention has been made in order to solve the above-described problems, and can detect the occurrence of distortion in a high-frequency amplifier and can automatically adjust the level of a signal input to the high-frequency amplifier to avoid the occurrence of distortion. It is an object of the present invention to provide a distortion detection device and a high-frequency amplification device that do not require confirmation with actual signals from various measuring instruments and television receivers and that do not require troublesome adjustment work.

The present invention relates to a high-frequency amplifier for receiving television broadcasts installed on a roof or in a high place together with a television antenna, a high-frequency amplifier for amplifying a signal in a television broadcast wave band, and reception input directly from the television antenna. An input signal level adjuster capable of manually adjusting the level to adjust the signal level to be an input signal of the high frequency amplifier, and a signal of a high frequency including a television broadcast wave band from the output signal of the high frequency amplifier. a high pass filter for outputting to the succeeding electronic device is passed through the low than TV broadcast wave band including the second-order distortion component from the output signal having a correlation in third-order distortion component and the levels generated on the TV broadcast wave in the band of the high frequency amplifier a low pass filter for passing a signal of a frequency of the frequency, an amplifier for amplifying the signal passed through the low pass filter More television to the detector and the output signal of the detector in the region of the level of the third-order distortion viewed component and second-order distortion component is correlated linearly converting a signal amplified by the amplifier to the detector and DC level signal A high-frequency amplifying apparatus for receiving a television broadcast for detecting the occurrence of distortion occurring in an image of a television receiver by detecting a level of a second-order distortion component that is a third-order distortion component level greater than a predetermined value that interferes with the image of the television comprising a notification means for notifying a light-emitting display of light emitting diodes provided in, but also to properly adjust at a remote position the input signal level adjuster from the television receiver based operator to notification of the notification unit It is possible to do.

  For example, when a television broadcast wave is amplified by the high-frequency amplifier, if the input to the high-frequency amplifier exceeds an appropriate level and is excessively input, second-order distortion occurs between the video carrier and the audio carrier or a plurality of television signals. Multi-order distortion components such as third-order distortion are generated, and interfere with television signals in the television broadcast wave band. The difference signal component of the two waves, which is one of the second-order distortion components, is generated in a band lower than the television broadcast wave band, so it does not substantially interfere with the television signal, but is correlated in level with the disturbing wave component. It will occur.

  Of the signal output from the high-frequency amplifier, a distortion component outside the set band, for example, a second-order distortion component, is selected by a filter and input to the detector. This detector detects the second-order distortion component selected by the filter, converts it into a DC component, and outputs it to the notification means. This notification means does not notify if the level of the secondary distortion component output from the high-frequency amplifier is smaller than a preset level and is in a normal state, but when the level of the secondary distortion component exceeds a preset level. The fact that distortion has occurred is notified, and the operator is informed that image disturbance or the like has occurred due to the distortion included in the output signal of the high-frequency amplifier. The operator confirms that the distortion is generated by the notification means and adjusts the input level of the high-frequency amplifier.

  According to the present invention, by detecting a signal outside the set band including a distortion component correlated with the distortion component generated in the set band included in the output signal of the high frequency amplifier, the presence / absence of an interference wave generated in the band is detected. As a result, the distortion component can be reliably detected without being affected by other channels. Alternatively, it is possible to automatically adjust the input signal level of the high frequency amplifier based on the detection signal to avoid the occurrence of distortion.

  Therefore, there is no need to check other actual devices such as measuring instruments or television receivers, and the work efficiency can be greatly improved, and quantitative adjustments that are not influenced by the subjectivity of the operator are possible. A simple receiving system.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a high-frequency amplification device having a distortion detection function according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a high-frequency amplification device having a distortion avoidance function according to an embodiment of the present invention.

  In FIG. 1, reference numeral 11 denotes an antenna for receiving television broadcast radio waves, and a signal received by the antenna 11 is input to the input terminal 13 of the high-frequency amplifier 12. The high-frequency amplifier 12 includes a signal level adjuster 14 and a high-frequency amplifier 15 that can be adjusted by manual operation. The signal input to the input terminal 13 is adjusted by the signal level adjuster 14 to be converted into a high-frequency amplifier 15. input. The high-frequency amplifier 15 uses, for example, a class A amplifier circuit. The signal adjusted by the signal level adjuster 14, for example, FM broadcasting (76 to 90 MHz) as shown in FIG. 2, VHF television broadcasting of 1 to 12 channels. (90 to 108 MHz, 170 to 222 MHz) Further, an electronic device downstream from the output terminal 17 through a high pass filter (HPF) 16 that amplifies a UHF television broadcast signal and passes a signal having a frequency of 70 MHz or higher, for example, Output to a television receiver.

  A distortion detection circuit 20 is connected between the high-frequency amplifier 15 and the high-pass filter 16. The distortion detection circuit 20 allows a signal outside a set band including a distortion component correlated with a distortion component generated in the set band among signals output from the high-frequency amplifier 15 to pass a signal having a frequency of 40 MHz or less, for example. Take out through a low-pass filter (LPF) 21. Further, the output signal of the low-pass filter 21 is amplified by the amplifier 22, detected by the detector 23, and input to the display drive circuit 24. The display drive circuit 24 drives the display lamp 25 such as an LED (Light Emitting Diode) based on the output signal of the detector 23.

  Next, in the embodiment of FIG. 2, a distortion detection automatic adjustment circuit 20 </ b> A is connected to the output side of the high frequency amplifier 15. The distortion detection automatic adjustment circuit 20A filters a signal outside the set band including a distortion component correlated with a distortion component generated in the set band, among signals output from the high frequency amplifier 15, for example, a signal having a frequency of 40 MHz or less. Is taken out through a low-pass filter (LPF) 21 that passes through. The high-pass filter 16 and the low-pass filter 21 constitute a duplexer.

  Further, the output signal of the low-pass filter 21 is amplified by the amplifier 22, detected by the detector 23, and input to the voltage comparator 26. The voltage comparator 26 includes, for example, a comparator 27 and a reference voltage source 28. The comparator 27 compares the output signal of the detector 23 with the reference voltage supplied from the reference voltage source 28, and adjusts the signal level based on the comparison output signal. The device 14 is controlled. Details of the signal level adjuster 14 and the voltage comparator 26 will be described later.

  In the above configuration, a television broadcast signal is received by the antenna 11 and input to the high frequency amplifier 12. The high frequency amplifier 12 adjusts the signal received by the antenna 11 by the signal level adjuster 14, amplifies the signal by the high frequency amplifier 15, and outputs the amplified signal from the output terminal 17 to the television receiver or the like via the high pass filter 16.

  When the third-order distortion due to, for example, a two-wave television reception signal occurs due to the nonlinear distortion of the high-frequency amplifier 15, and a video or audio disturbance occurs, the second-order distortion correlated with the third-order distortion. Will occur. The third-order distortion is generated in the band of the television signal, but the second-order distortion is generated in a frequency lower than the band of the television signal, for example, a band of 40 MHz or less.

  The distortion detection automatic adjustment circuit 20A extracts a distortion component of 40 MHz or less exceeding a predetermined level, for example, a second-order distortion component from the signal output from the high-frequency amplifier 15 through the low-pass filter 21 and amplifies it by the amplifier 22. The signal is detected by the detector 23 and converted into a DC component, input to the voltage comparator 26, compared with the reference voltage supplied from the reference voltage source 28 by the comparator 27, and the comparison output signal is fed back to the signal level adjuster 14. To do.

In this case, if the level of the secondary distortion component output from the high frequency amplifier 15 is smaller than a preset level, the voltage comparator 26 adjusts the signal level adjuster until the level of the secondary distortion component reaches a preset level. The voltage signal level for driving 14 is increased. However, if the level of the secondary distortion component output from the high frequency amplifier 15 is equal to or higher than a preset level, the voltage comparator 26 lowers the voltage signal for driving the signal level adjuster 14 by the secondary distortion component. Let
As described above, the distortion component included in the output signal of the high-frequency amplifier 15 is detected and the signal level adjuster 14 is automatically controlled to avoid the occurrence of distortion in the high-frequency amplifier 15.

Next, details of the signal level adjuster 14 and the voltage comparator 26 will be described with reference to FIG.
The voltage comparator 26 includes the comparator 27 and the reference voltage source 28 as described above. The signal detected by the detector 23 is converted into a DC component and input from the input terminal 31 to the negative terminal of the comparator 27. The reference voltage is supplied from the reference voltage source 28 to the + terminal of the comparator 27.

  The reference voltage source 28 has a capacitor 32 connected between the + E power line and the ground, and is connected to a series circuit of a resistor 33, a variable resistor 34, and a resistor 35, and is taken out from a sliding terminal of the variable resistor 34. A voltage is supplied to the + terminal of the comparator 27 via the resistor 36. A capacitor 37 is connected between the + terminal of the comparator 27 and the ground.

  As described above, the reference voltage source 28 divides the + E voltage of the power supply line by the series circuit of the resistor 33, the variable resistor 34, and the resistor 35, and uses the divided voltage taken out from the sliding terminal of the variable resistor 34 as the reference voltage. The voltage is supplied to the + terminal of the comparator 27 through the resistor 36. The value of the reference voltage can be arbitrarily adjusted by the variable resistor 34, whereby the operation of the signal level adjuster 14 can be set to an appropriate state.

  A resistor 38 and a capacitor 39 are connected in parallel between the negative terminal and the output terminal of the comparator 27. Further, a capacitor 40 is connected between the output terminal of the comparator 27 and the ground. The comparator 27 compares the signal detected by the detector 23 with the reference voltage supplied from the reference voltage source 28 and outputs the comparison output voltage to the signal level adjuster 14 via the resistor 42.

  The signal level adjuster 14 is mainly composed of, for example, NPN transistors Tr1 and Tr2 and PIN diodes D1 to D6 for signal level adjustment. A high frequency signal is input from the input terminal 51 via the capacitor 52 to the base of the transistor Tr1. Further, the voltage of + E of the power supply line is divided by the resistors 53 and 54 and applied to the base of the transistor Tr1. The emitter of the transistor Tr1 is grounded via resistors 55 and 56, and a capacitor 57 is connected in parallel to the resistor 56.

  The transistors Tr1 and Tr2 are cascade-connected, and the collector of the transistor Tr1 is connected to the emitter of the transistor Tr2 via the high-frequency coils 58 and 59 and the resistor 60. The connection point between the high frequency coils 58 and 59 is grounded via a capacitor 61, and the connection point between the high frequency coil 59 and a resistor 60 is grounded via a capacitor 62.

  A high-frequency signal extracted from the collector of the transistor Tr1 is input to the base of the transistor Tr2 via the capacitors 64 and 65, the reversely connected PIN diode D1, and the capacitors 66 and 67. A series circuit of resistors 68 and 69 is provided between the midpoint of the capacitors 64 and 65 and the base of the transistor Tr1, and a high-frequency coil 70 is connected in parallel to the resistor 69.

  The cathode side of the PIN diode D1 is grounded via a resistor 71, and is grounded via a resistor 72, a reversely connected PIN diode D2 and a capacitor 73. The midpoints of the capacitors 66 and 67 are grounded via a resistor 74, a forward-connected PIN diode D3 and a capacitor 75, and grounded via a high-frequency coil 76 and a capacitor 77. The anode of the PIN diode D2 and the cathode of the PIN diode D3 are connected.

  The base of the transistor Tr2 is grounded through a resistor 78. The collector of the transistor Tr2 is supplied with + E voltage from the power supply line via the resistor 79 and the high frequency coil 80. A connection point between the resistor 79 and the high frequency coil 80 is grounded via a capacitor 90. The high-frequency signal amplified by the transistor Tr2 is taken out from the intermediate tap of the high-frequency coil 80, and is output to the output terminal 100 via the capacitor 81, the reversely connected PIN diode D4, and the capacitors 82 and 83.

  Further, resistors 84, 85, 86 are provided in series between the base of the transistor Tr 2 and the intermediate tap of the high frequency coil 80, and a high frequency coil 87 is connected in parallel to the resistor 84. On the other hand, a capacitor 88 is connected in parallel. Further, high-frequency coils 91 and 92 are connected in series between the anode of the PIN diode D1 and the cathode of the PIN diode D4, and a capacitor 93 is provided between the midpoint of the high-frequency coils 91 and 92 and the ground.

  The cathode side of the PIN diode D4 is grounded through a series circuit of a capacitor 94, a reverse-connected PIN diode D5, a resistor 95, and a capacitor 96. The cathode side of the PIN diode D5 is grounded via a high frequency coil 97 and a capacitor 98. A connection point between the high frequency coil 97 and the capacitor 98 is connected to a connection point between the high frequency coil 76 and the capacitor 77.

  The output terminal 100 is grounded via a resistor 101, and is grounded via a resistor 102, a forward-connected PIN diode D6, and a capacitor 103. The cathode side of the PIN diode D6 is connected to a connection point between the resistor 95 and the capacitor 96.

  The output terminal 100 is supplied with + E voltage from the power supply line via the resistors 104 and 105. The connection point between the resistors 104 and 105 is grounded via a capacitor 106.

  The comparison output voltage of the voltage comparator 26, that is, the voltage output from the comparator 27 via the resistor 42 is supplied to the anode of the PIN diode D 4 via the high frequency coil 107. A connection point between the high-frequency coil 101 and the resistor 42 is grounded via a capacitor 108.

  The signal level adjuster 14 configured as described above forms a π-type variable attenuator with the PIN diodes D1 to D3 and the PIN diodes D4 to D6, respectively, and adjusts the level of the signal passing therethrough. Note that the signal attenuation is compensated by amplification by the transistors Tr1 and Tr2.

  The PIN diodes D1 to D6 are: pin diode D4 → high frequency coil 92, 91 → pin diode D1 → resistor 72 → pin diode D2, D3 → resistor 74 → high frequency coil 76, 97 → pin diode D5 → resistor 95 pin diode D6 → The resistors 102, 105, and 104 are connected in a direct current order, and the bias is controlled by the comparison output voltage given from the voltage comparator 26 via the high-frequency coil 107, whereby the signal level that passes through the impedance changes. Adjusted.

  In this case, the PIN diodes D1 and D4 are given a forward bias by the comparison output voltage given from the voltage comparator 26 via the high frequency coil 107, and the impedance is controlled accordingly. The PIN diodes D2, D3, D5, and D6 are a constant forward bias supplied from the power supply line to the anode side of the pin diode D6 through the resistors 104 and 105 and the resistor 102, and the PIN diode from the voltage comparator 26. Impedance is controlled by a reverse bias applied to the cathode side via D4 and D1.

  That is, if the level of the secondary distortion component output from the high frequency amplifier 15 is small and the level of the signal detected by the detector 23 is smaller than the reference voltage supplied from the reference voltage source 28, the output voltage of the comparator 27 increases. . When the output voltage of the comparator 27 increases, the impedances of the PIN diodes D1 and D4 of the signal level adjuster 14 decrease and the impedances of the PIN diodes D2, D3, D5, and D6 increase, and the signal attenuation in the signal level adjuster 14 occurs. The amount becomes smaller. As a result, the level of the signal output from the high frequency amplifier 15 increases.

  However, when the level of the second-order distortion component output from the high-frequency amplifier 15 is equal to or higher than a preset level, that is, when the level of the signal detected by the detector 23 is higher than the reference voltage supplied from the reference voltage source 28, The output voltage of the comparator 27 decreases. When the output voltage of the comparator 27 decreases, the impedances of the PIN diodes D1 and D4 of the signal level adjuster 14 increase and the impedances of the PIN diodes D2, D3, D5, and D6 decrease, and the signal attenuation in the signal level adjuster 14 is reduced. Becomes larger. As a result, the level of the signal output from the high frequency amplifier 15 decreases.

  As described above, the signal level adjuster 14 is automatically adjusted by the output signal of the voltage comparator 26 so that the distortion component included in the output signal of the high frequency amplifier 15 is always constant.

  Next, generation of distortion in the high-frequency amplifier 15 will be described in more detail with reference to FIG. Here, for example, the occurrence of distortion in the 8, 10, and 12 channels of a VHF television will be considered.

The video frequencies f ₈ , f ₁₀ , f ₁₂ of the ₈ , ₁₀ , 12 channels are
f _8: 193.25MHz
f ₁₀ : 205.25 MHz
f ₁₂ : 217.25 MHz
It is.

The third-order distortion component H3 in the above 8 and 10 channels is
H3 = 2 × f ₁₀ −f ₈
= 2 × 205.25 (MHz) -193.25 (MHz)
= 217.25 (MHz)
= F ₁₂
It becomes. Third-order distortion component H3 in 8 channels and 10 channels as described above, consistent with 217.25MHz, and the 12 channel video frequency _{f 12} of, cause interference to 12 channels of video signals.

Also, the second order distortion component H2 in the above 8 channel and 10 channel is
H2 = f ₁₀ −f ₈
= 205.25 (MHz) -193.25 (MHz)
= 12 (MHz)
It becomes.

  As described above, the secondary distortion component H2 in the 8th channel and the 10th channel is 40 MHz or less at 12 MHz, that is, outside the band of the television broadcast channel, and has a correlation with the third order distortion component H3.

  FIG. 5 is a diagram showing the third-order distortion characteristics at the time of two-wave input of an actual television receiving amplifier. The horizontal axis represents the signal output level (dBμ), and the vertical axis represents the third-order distortion (dB). Indicated. The part a in the figure is a linear (straight line) region where the input signal pair third-order distortion changes at 1: 3, and the part b is outside the linear region where the input signal pair third-order distortion does not change at 1: 3. Is shown. In the measured performance of the television receiver amplifier, the maximum output level at which a standard third-order distortion (intermodulation distortion) indicating the performance that can be output without being affected by an interference signal due to distortion can be ensured to −52 dB at the time of reception is as shown in FIG. From the distortion characteristics, it can be seen that it is 105 dBμ.

  FIG. 6 is a diagram showing the second-order distortion characteristics of the television receiver amplifier when two waves are input. The horizontal axis represents the signal output level (dBμ), and the vertical axis represents the second-order distortion (dB). It was. In the figure, the part c shows a linear region where the second order distortion of the input signal is changed by 1: 2, and the part d shows the outside of the linear region where the second order distortion of the input signal is not changed by 1: 2. Yes. The third-order distortion a region in FIG. 5 and the second-order distortion c region in FIG. 6 are both linear regions and maintain a correlation.

  The standard third-order distortion (intermodulation distortion) of the high-frequency amplifier for television is about -52 dB, and the maximum output level of the amplifier that can secure about -52 dB is about 105 to 110 dBμ. The output level of the second-order distortion of the amplifying apparatus corresponding to the third-order distortion is about 50 dBμ. Accordingly, in the distortion detection automatic adjustment circuit 20A, a secondary distortion component exceeding 50 dBμ is extracted from the output signal of the high frequency amplifier 15 by the low pass filter 21, detected by the detector 23 and input to the voltage comparator 26, and the comparison output thereof. Thus, the signal level adjuster 14 is controlled.

  In general, in a television receiving amplifier, the point of the output level at which distortion disturbs a television image is correlated with the second order distortion and the third order distortion, which are linear in the region a in FIG. 5 and the region c in FIG. It can be seen that it suffices to detect the level of the distortion component in the linear region.

  However, when the third-order distortion is detected when the third-order distortion is within the band of the television channel, the signals of other channels may be detected. For this reason, in this embodiment, the interference wave generated within the band is detected by detecting the secondary distortion correlated with the third distortion outside the band of the television channel. As a result, it is possible to reliably detect the distortion component without being influenced by other channels and automatically adjust the signal level adjuster 14 based on the detected signal.

  Accordingly, in addition to the high-frequency amplifier 12, it is not necessary to check the actual signal of a device such as a measuring instrument or a television receiver, and a troublesome adjustment work is not required, so that a high-quality receiving system can be obtained.

  5 and 6 show the distortion characteristics of the television receiver amplifier in the VHF television channel, but the UHF television channel also has a correlation between the third-order distortion and the second-order distortion.

  FIGS. 7A and 7B show the relationship between the output level and the third-order and second-order distortion when the input frequency to the television receiver amplifier is 611 MHz (UHF 36 channel center frequency) and 617 MHz (UHF 37 channel center frequency). The measurement results are shown. FIG. 8 is a graph showing the measurement results.

  As is apparent from FIG. 8, the TV receiving amplifier has a correlation between the third-order distortion and the second-order distortion even in the UHF TV channel.

  As described above, there is a correlation between multi-order distortion generated in an amplifier, for example, second-order distortion and third-order distortion, which has been published by a publication such as the Japan Broadcasting Corporation on September 20, 1974. Furthermore, “TV joint reception technology”, p. 38 to 43 “2.3.5 Mathematical explanation of nonlinear distortion” and the like are known.

  In the above embodiment, the case where the second distortion component is detected by the distortion detection automatic adjustment circuit 20A and the signal level adjuster 14 is adjusted has been described, but the distortion component to be detected is not limited to the second distortion component, By selecting a distortion component to be detected according to the intended use, from the 3rd order to the 4th order, it is possible to make an accurate determination, and it is possible to perform appropriate processing. That is, by detecting a distortion component generated outside the band of the television broadcast channel, the signal level adjuster 14 can be adjusted by reliably detecting the distortion component without being influenced by other channels.

  When the distortion component to be detected is small, the distortion component can be reliably detected by inserting the amplifier 22 in the frequency band to be detected before the detector 23 as shown in FIG. On the contrary, when a distortion component to be detected is large, the amplifier 22 is not necessary and an attenuation circuit may be inserted.

  Further, in the above embodiment, the signal level is automatically controlled so that the interference wave is not generated. However, when the interference wave is generated, for example, an indicator light such as an LED (Light Emitting Diode), a buzzer, The operator may be notified by voice or vibration.

  In the above embodiment, the signal level is automatically controlled when an interference wave is generated. However, the present invention is also applied as a protection circuit for preventing destruction due to excessive input to a semiconductor element of a high-frequency amplifier circuit. Can be applied. In that case, since the purpose is not to suppress image interference due to distortion, the reference voltage level of the comparator 27 of the embodiment is set to a level suitable for the purpose.

  Further, the distortion detection automatic adjustment circuit 20A in the above embodiment extracts the distortion component outside the set band exceeding the set level from the output signal of the high-frequency amplifier 15 by the low-pass filter 21. It is also possible to extract up to a low level distortion component and then adjust the signal level adjuster 14 by detecting the distortion component above the set level from the detection output of the detector 23 by the voltage comparator 26.

Furthermore, in the above embodiment, the case where a television broadcast radio wave is received and amplified has been described. However, the present invention can also be applied to an amplifier used in, for example, a wireless communication device in the same manner as in the above embodiment.
The present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying constituent elements without departing from the scope of the invention in the implementation stage.

The block diagram which shows the structure of the high frequency amplifier provided with the distortion detection function which concerns on one Embodiment of this invention. 1 is a block diagram showing the overall configuration of a high-frequency amplification device having a distortion detection automatic adjustment function according to an embodiment of the present invention. The circuit block diagram which shows the detail of the signal level adjuster and distortion detection automatic adjustment circuit in the embodiment. A figure for explaining distortion detection operation in the embodiment. The figure which shows the 3rd-order distortion characteristic at the time of 2 wave input of a television receiver amplifier. The figure which shows the secondary distortion characteristic at the time of the 2 wave input of a television receiving amplifier. The figure which shows the result of having measured the relationship between the output level in the case where the input frequency to a television receiving amplifier is 611 MHz and 617 MHz, and the 3rd order and 2nd order distortion. The figure which shows the measurement result in FIG. 7 in a graph. The block diagram which shows the structural example of the conventional high frequency amplifier.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Antenna, 12 ... High frequency amplifier, 13 ... Input terminal, 14 ... Signal level adjuster, 15 ... High frequency amplifier, 16 ... High pass filter, 17 ... Output terminal, 20 ... Distortion detection circuit, 20A ... Distortion detection automatic adjustment circuit , 21 ... Low-pass filter, 22 ... Amplifier, 23 ... Detector, 24 ... Display drive circuit, 25 ... Indicator lamp, 26 ... Voltage comparator, 27 ... Comparator, 28 ... Reference voltage source, Tr1, Tr2 ... Transistor, D1 D6: PIN diode.

Claims (1)

In a high-frequency amplifier for receiving television broadcasts installed on a roof or in a high place with a TV antenna,
A high-frequency amplifier that amplifies a signal in a television broadcast wave band, and an input signal level adjuster that can adjust a level by a manual operation by adjusting a level of a reception signal directly input from the television antenna to be an input signal of the high-frequency amplifier A high-pass filter that passes a high-frequency signal including a television broadcast wave band from the output signal of the high-frequency amplifier and outputs the signal to a subsequent electronic device, and is generated in the television broadcast wave band from the output signal of the high-frequency amplifier A low-pass filter that passes a signal having a frequency lower than a television broadcast wave band including a second-order distortion component that is correlated in level with a third-order distortion component, an amplifier that amplifies the signal that has passed through the low-pass filter , and the amplifier detects the amplified signal and detector for converting the direct current level signal, the third-order distortion viewed component and second-order distortion components linear By detecting the level of second-order distortion component as a predetermined value or more third-order distortion component levels provide more interference to the television receiver of the image on an output signal of the detector in the region of the level of correlation, the television receiver image the occurrence of distortion; and a notifying means for notifying the luminous display of light emitting diodes provided in the high frequency amplifying device for the television broadcast receiver that occurs, the operator said input signal level adjustment on the basis of the notification of the notification unit A high-frequency amplifier for receiving a television broadcast with a distortion detection function, wherein the receiver can be appropriately adjusted even at a remote location from the television receiver .

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