JP2003244005A - Low noise converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low noise converter capable of receiving a signal even when a frequency band to be received differs without the need for another converter, wherein intermediate frequency signals cause no interference. <P>SOLUTION: Low noise amplifiers 3, 4 amplify a first high frequency signal with a prescribed frequency band to obtain a low noise output, low noise amplifiers 5, 6 amplify a received second high frequency signal with a narrow frequency band to obtain a low noise output, a BPF 7a passes through only a prescribed frequency band component among outputs from the low noise amplifiers 3, 4, a BPF 8a passes through only a narrow frequency band component among outputs from the low noise amplifiers 5, 6, a mixer 11 mixes outputs of the BPFs 7a, 8a with a local oscillation signal to convert the outputs into intermediate frequency signals, and an IF amplifier 16 amplifies the intermediate frequency signals and provides an output. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low noise converter, and in particular, it is used for an LNB (Low Noise Block down-converter) mounted in a receiver of a satellite signal transmitting / receiving antenna, and has two different polarizations and different frequency bands. The present invention relates to a low noise converter for converting an input signal into an intermediate frequency (IF) band and transmitting the same to an indoor unit (indoor receiver).

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a typical conventional satellite broadcast receiving system. In FIG. 7, a feed horn and a cross polarization separator 110 are attached to the antenna 101. The LNB 102 is a part of what is called outdoor of this system, and the orthogonal polarization separator 1
It is installed in the latter part of 10. And LNB102
Is an indoor receiver 104, which amplifies weak radio waves from the satellite with low noise and is connected next via the coaxial cable 103.
To provide a low noise and sufficient level signal.

The indoor receiver 104 includes a DBS tuner 105, an FM demodulator 106, a video / audio circuit 107 and an RF modulator 108, and a signal given from the coaxial cable 103 is processed by these circuits and is sent to a television receiver 109. Given.

FIG. 8 is a block diagram showing a conventional example of the LNB shown in FIG. The LNB shown in FIG. 8 is a satellite broadcast / communication reception LNB capable of receiving multiple polarizations, and is intended for Ku band satellite signal reception in the United States.

In FIG. 8, the input frequency is 11.7 GHz.
An incoming signal of up to 12.2 GHz is split into a horizontal polarization signal and a vertical polarization signal by the orthogonal polarization separator after the feed horn, and then the input 1 which is the input of two different LNBs for each signal. And input 2 are provided. The signals from these two inputs are picked up by the antenna probe. Next, each input signal is a low noise amplifier (LN
A) After low-noise amplification in 3 to 6, it passes through a desired frequency band and passes through BPFs (Band Pass Filters) 7 and 8 which have a role of removing signals in the image frequency band.

Thereafter, one of the signals is a local oscillator (Local
The oscillation signal 10.75 GHz from the Oscillator 9 is injected into the mixing circuit (Mixer) 11, where 950
-1450MHz intermediate frequency: IF (Intermediate F
frequency is converted into a signal in the requency band. The other signal is the oscillation signal 10.15 GHz from the local oscillator 10,
Injected into mixer 12, where 1550 to 2050 MH
The frequency is converted into a signal in the intermediate frequency band of z. The signals in these two bands are combined by a combining circuit, for example, a Y-type 2 distribution circuit 15, and then transmitted / amplified to an IF amplifier 16 so as to have appropriate noise characteristics and gain characteristics, and one IF signal is obtained.
It is output from the output terminal 17.

The IF output terminal 17 has an indoor receiver 1
A DC voltage from 04 is superposed on the output signal and sent from the coaxial cable, and the power supply circuit 18 extracts the DC voltage to a predetermined potential and supplies it to each circuit.

[0008]

The LNB shown in FIG. 8 has different polarization planes for both inputs 1 and 2, but has a frequency band of 1
It becomes the same at 1.7 to 12.2 GHz, and BPF1
Reference numerals 3 and 14 are configured to remove signals in the image frequency band. However, the input frequency band is, for example, 11.7 to 12.75 GHz and 12.2 depending on the customer's request.
There are cases where the low frequency side is different, such as -12.75 GHz. In such a case, conventionally, the frequencies of the respective bands are received by different LNBs, but it is uneconomical because two LNBs are required, and it is possible to receive by one LNB even in different frequency bands. Is required to be configured. However, when two input signals having different frequency bands are converted into an intermediate frequency signal by one LNB, they interfere with each other and the cross polarization characteristic deteriorates.

Therefore, a main object of the present invention is to achieve low noise in which one unit can receive signals even if the frequency bands to be received are different and the intermediate frequency signals do not interfere with each other to deteriorate the polarization characteristics. It is to provide a converter.

[0010]

According to the present invention, a low frequency signal is received by a horn antenna that receives a first high frequency signal having a predetermined frequency band and a second high frequency signal having a frequency band narrower than the predetermined frequency band. A noise converter, comprising: a first low-noise amplifier that amplifies a received first high-frequency signal with low noise; a second low-noise amplifier that low-noise amplifies a received second high-frequency signal; A first filter which passes only a predetermined frequency band component of the output of the low noise amplifier, a second filter which passes only a narrow frequency band component of the output of the second low noise amplifier, and a first filter Alternatively, a frequency conversion circuit that mixes the second filter output and the local oscillation signal to output an intermediate frequency signal, and an intermediate frequency amplification circuit that amplifies and outputs the intermediate frequency signal output from the frequency biasing circuit are provided. Characterized in that was.

The frequency conversion circuit mixes the local oscillation circuit for outputting the local oscillation signal, the first filter output and the local oscillation signal from the local oscillation circuit, and outputs the first intermediate frequency signal. From the first and second mixing circuits, the first mixing circuit, the second mixing circuit that mixes the second filter output and the local oscillation signal from the local oscillation circuit and outputs the second intermediate frequency signal, And a switching circuit for switching and outputting the output first and second intermediate frequency signals.

Further, a trap circuit for trapping the lower limit frequency component of the intermediate frequency signal corresponding to each of the terminals to which the local oscillation signals of the first and second mixing circuits are input is connected.

Further, the local oscillator circuit includes first and second oscillator circuits, and the first mixer circuit mixes the first filter output and the local oscillator signal from the first oscillator circuit to produce a first oscillator signal.
Is output, and the second mixing circuit mixes the second filter output and the local oscillation signal from the second oscillation circuit to output the second intermediate frequency signal.

[0014]

1 is a schematic block diagram of a low noise converter according to an embodiment of the present invention, and FIG. 2 is a diagram showing band characteristics of the BPF shown in FIG.

In FIG. 1, the reception frequency is 11.7 to 12.75 GHz in the 12 GHz band and 1 in this embodiment.
It shall receive two input signals of 2.2 to 12.75 GHz. The polarization planes of these two input signals may be horizontal / vertical or right-handed / left-handed.

Antenna probes 21, 22 in the waveguide 1
The two input signals are received by the low-noise amplifiers 3, 4 and 5, 6 and then low-noise amplified by the low-noise amplifiers 3, 4, 5 and 6, respectively, and then the required frequency band components pass by the BPFs 7a and 8a, respectively. Are removed. For this reason, the BPFs 7a and 8a are, as shown in FIGS. 2A and 2B, respectively, 11.5 to 12.75 GHz and 12.2 GHz.
It has a pass characteristic for passing signals in each band of 12.75 GHz. BPF7 with such different passage characteristics
By passing through a and 8a, it is possible to make a difference in the pass characteristic of the high frequency signal after passing through the filter, and it is possible to reduce interference in the high frequency band.

The high-frequency signals that have passed through the filter are mixed and given to the mixer 11 which constitutes the frequency conversion circuit, and the mixer 11 oscillates from the local oscillator circuit 10.6.
Mixed with a local oscillation signal of 78 GHz,
An intermediate frequency signal of 72 MHz is output, the intermediate frequency signal is amplified by the IF amplifier 16, and then the IF output terminal 17
Is output from.

As described above, according to this embodiment, by inserting the BPFs 7a and 8a having different pass characteristics in the high frequency signal lines having different reception frequency bands, the interference after the conversion into the intermediate frequency signal is efficiently reduced. Therefore, it is possible to prevent the cross polarization characteristic from deteriorating.

FIG. 3 is a block diagram of a low noise converter according to another embodiment of the present invention. This embodiment is
Two mixers 11 and 12 are provided, and 11.5 to 12.75
Input signal of GHz, 12.2 to 12.75 GHz and 1
The local oscillation signal of 0.678 GHz is mixed and the intermediate frequency signal of the output is switched by the switching circuit 20. Each of the switched intermediate frequency signals is an IF amplifier 1
The signals are amplified by 6 and 19 and output from the IF output terminals 171 and 172.

In the embodiment shown in FIG. 1, 11.5-1.
While only one of the intermediate frequency signals based on the received signals in each band of 2.75 GHz and 12.2 to 12.75 GHz can be output, the intermediate frequency signal based on both received signals is output in the embodiment of FIG. You can switch and output
Moreover, these intermediate frequency signals do not interfere with each other.

FIG. 4 shows still another embodiment of the present invention, in which a trap is inserted between the mixers 11 and 12 and the local oscillation circuit 9 of FIG. The trap is composed of an inductor L1 connected to drop the RF band, an inductor L2 connected to drop the IF band, and a capacitor C1. The inductors L1 and L2 and the capacitor C1 are connected between the mixer and the local oscillation signal input. Such inductors L1 and L2 and the capacitor C1 are realized by forming a pattern on a substrate, for example. The inductance value and the capacitance value can be easily adjusted by changing the width or length of the pattern.

FIG. 5 is a diagram showing an intermediate frequency characteristic due to the insertion of the trap shown in FIG. 4, and particularly FIG. 5 (a).
Shows the characteristics of the RF band, and FIG. 5B shows the characteristics of the IF band. In FIG. 5, the solid line shows the intermediate frequency signal characteristic when the trap is not inserted, the alternate long and short dash line shows the characteristic due to the trap, and the dotted line shows the intermediate frequency characteristic when the trap is inserted. By inserting the trap (a), the cutoff characteristic near the lower limit frequency of 12.2 GHz of the input frequency signal and by inserting the trap (b) near the lower limit frequency of 1522 MHz of the intermediate frequency signal can be made sharp, and the cross polarization can be suppressed. The wave characteristics can be further improved.

FIG. 6 is a block diagram of a low noise converter according to still another embodiment of the present invention. In this embodiment, two systems of local oscillation circuits 9a and 9b are provided to efficiently reduce interference of signal lines. That is,
One input signal of 11.7 to 12.75 GHz is low-noise amplified by the low-noise amplifiers 3, 41 and 42, and the BPF 7a,
It is input to the mixers 11a and 11b after being limited to the band of 11.7 to 12.75 GHz by 7b. 12.2-12.
The other input signal of 75 GHz is low noise amplified by the low noise amplifiers 5 and 6, and is 12.2 to 12.75 GHz by the BPF 8.
And is input to the mixer 12.

The mixers 11b and 12 are local oscillator circuits 9b.
Local oscillation signal from (10.678 GHz) and 11.7
˜1.22 MHz, 12.2-12.75 GHz input signal mixed, 1022-1522 MHz, 152
It outputs an intermediate frequency signal of 2 to 2072 MHz. The mixer 11a mixes the local oscillation signal from the local oscillation circuit 9a (11.178 GHz) and the input signal of 12.2 to 12.75 GHz, and outputs an intermediate frequency signal of 1022 to 1572 MHz.

These intermediate frequency signals are 3 × 2 SW-I.
It is switched by the switching circuit 20a composed of C and output to the IF amplifiers 16 and 19.

By configuring as described above, even for the common 12.2 to 12.75 GHz, the IF band is 1522 to 2072 MHz and 1022 to 1572 MHz.
Since it can be divided into two, the cross polarization characteristics can be efficiently improved.

The embodiments disclosed this time are to be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[0028]

As described above, according to the present invention, the first
A first filter that passes only a predetermined frequency band component of the second high frequency signal, and a second filter that passes only a narrow frequency band component of the second high frequency signal having a frequency band narrower than the predetermined frequency band. By incorporating the second filter and the low-noise amplifier in the low-noise amplifier, the intermediate frequency signals do not interfere with each other, and the cross polarization characteristics can be improved.

[Brief description of drawings]

FIG. 1 is a schematic block diagram of a low noise converter according to an embodiment of the present invention.

FIG. 2 is a diagram showing band characteristics of the BPF shown in FIG.

FIG. 3 is a block diagram of a low noise converter according to another embodiment of the present invention.

FIG. 4 is a diagram showing a main part of a low noise converter according to still another embodiment of the present invention.

FIG. 5 is a block diagram of a low noise converter according to still another embodiment of the present invention.

FIG. 6 is a block diagram of a low noise converter according to still another embodiment of the present invention.

FIG. 7 is a block diagram showing a conventional typical satellite broadcast receiving system.

8 is a block diagram showing a conventional example of the LNB shown in FIG.

[Explanation of symbols]

1 waveguide, 3 to 6, 41, 42 low noise amplifier, 7
a, 7b, 8, 8a BPF, 9, 9a, 9b Local oscillation circuit, 11, 11a, 11b, 12 mixer, 16,
19 IF amplifier, 17, 171, 172 IF output terminal, 18 power supply circuit, 20, 20a switching circuit 21,
22 probe, L1, L2 inductor, C1 capacitor.

Claims (4)

[Claims] 1. A low noise converter for receiving a first high frequency signal having a predetermined frequency band and a second high frequency signal having a frequency band narrower than the predetermined frequency band by a single horn antenna, wherein the reception is performed. For low-noise amplification of the generated first high-frequency signal
Low noise amplifier, and a second noise amplifier for low noise amplifying the received second high frequency signal.
Low-noise amplifier, a first filter that passes only the predetermined frequency band component of the output of the first low-noise amplifier, and a component of the narrow frequency band of the output of the second low-noise amplifier. A second filter that passes only the signal, a frequency conversion circuit that mixes the first or second filter output and the local oscillation signal to output an intermediate frequency signal, and an intermediate frequency signal output from the frequency biasing circuit A low noise converter, comprising: an intermediate frequency amplifier circuit that amplifies and outputs the signal. 2. The frequency conversion circuit mixes a local oscillation circuit that outputs the local oscillation signal, the first filter output, and the local oscillation signal from the local oscillation circuit to obtain a first intermediate frequency signal. A first mixing circuit that outputs a second intermediate frequency signal by mixing the second filter output and a local oscillation signal from the local oscillation circuit, and outputting a second intermediate frequency signal; And a switching circuit for switching and outputting the first and second intermediate frequency signals output from the second mixing circuit, The low noise converter according to claim 1, further comprising: 3. A trap circuit for trapping a lower limit frequency component of an intermediate frequency signal corresponding to each of the terminals of the first and second mixing circuits to which the local oscillation signal is input is connected. The low noise converter according to claim 2. 4. The local oscillator circuit includes first and second oscillator circuits, and the first mixer circuit mixes the first filter output and the local oscillator signal from the first oscillator circuit. The first
Of the intermediate frequency signal of the second oscillation circuit, and the second mixing circuit mixes the second filter output with the local oscillation signal from the second oscillation circuit to output the second oscillation signal.
3. Outputting the intermediate frequency signal of
Low noise converter described in.