JPS58161537A - Wide band receiving tuner - Google Patents

Abstract

PURPOSE:To realize a miniature and economical wide band receiving turner, by incorporating a video intermediate frequency filter at the rear stage side of a mixer. CONSTITUTION:A video intermediate frequency (VIF) filter part 22 is provided at the rear stage side of mixers 5 and 9 within a wide band receiving tuner 17. The part 22 contains a VIF filter circuit 20 and a VIF amplifier 21. Owing to such constitution, a coaxial cable of 50OMEGA or 75OMEGA which connects the tuner part and the VIF filter part and an input/output connector of the coaxial cable can be eliminated. This process realizes the miniaturization and a low cost of the tuner 17. Furthermore no circuit is needed to compensate the electric length, phase, etc. since no coaxial cable is used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wideband receiving tuner for receiving 1dVHF, 0ATV, and UHFHF nanotelevision signals.

An example of a conventional wideband reception tuner will be explained with reference to FIG. 1 is an input terminal of the tuner, which is a connector terminal of about 75Ω. 2 is the input filter circuit section, which is composed of a switching circuit, a bypass filter (HPF), a low pass filter (LPF), and a bandstop filter (BSF) circuit, and the insertion loss is 0 within the band.
．． It is about 7 to 1.0 dB. Reference numeral 3 denotes a wideband variable attenuator, to which an appropriate voltage is externally supplied to the AGC terminal 16 in order to maintain the signal from the input filter circuit section 2 at an appropriate level. Insertion loss is about 0.8 to 1.2 dB. Reference numeral 4 denotes a wideband amplifier, which amplifies the signal from the wideband variable attenuator 3 to an appropriate level. Conventionally, tuners with this configuration have noise figures (NF) according to target specifications.
), a gain of about 13 to 20 is required, and in this broadband amplifier 4, depending on the specifications, the NF
is set to about 2.0 to 3.0 dB. 6
is the first mixer, which mixes the signal from the broadband amplifier 4 and the signal from the voltage controlled oscillator (VCO) 7, and
It extracts the first intermediate frequency signal above the band, and the conversion loss is about 7 dB. 1% crossModula
The tion level is set according to the specifications, and is 11
A 0M value of about 5 dBIIV can be achieved. 6
is a buffer amplifier or a signal amplifier for the voltage controlled oscillator 7. Reference numeral 8 denotes a band P-wave device for passing the first intermediate frequency signal and removing unnecessary signals, and has a bandwidth of 6 MHz and an insertion loss of about 5.0 dB. 9 is a second mixer, which mixes the first intermediate frequency signal from the bandpass transducer 8 and the signal from the fixed oscillator 1o and converts it into a second intermediate frequency (standard intermediate frequency) signal, and the conversion loss is At about 5 dB,
1% Cross Modulation (CM)
Level can be set according to specifications. 11
is a second intermediate frequency amplifier (standard intermediate frequency amplifier). For example, the standard intermediate frequency is the 58 MH2 band in the case of the Japanese channel. 12 is an output connector for taking out a standard intermediate frequency signal. Conventionally, the tuner section 17 has generally been configured with the above-mentioned functions, and this also applies to single superheterogeneous not tuners. The standard intermediate frequency signal from the output terminal 12 of the tuner section 17 is transmitted to the video intermediate frequency (hereinafter referred to as VIP) filter section 1 via a 5oΩ or 75Ω coaxial cable 13.
Guided by 4. The video intermediate frequency (for example, 58.75 MH2 for the Japanese channel) and the audio intermediate frequency (for example, 54.25 MH2 for the Japanese channel) are filtered to an appropriate level by the VIP filter unit 14.
) 16 is led to an IC (not shown) in which a VIF amplification section, a video detection section, a video amplification section, etc. are formed, and is processed by a video processing circuit. Since these processing circuits and the following are generally well known in the art, details will be omitted.

The conventional configuration of the broadband reception tuner and the video intermediate frequency filter section shown in FIG. 1 has the following drawbacks. A disadvantage is that a predetermined length of 6oΩ or 76Ω coaxial cable and connector are required for connection between the tuner section 17 and the video intermediate frequency (VIP) filter section 14, which prevents miniaturization and cost reduction. has. Furthermore, since the coaxial cable 13 is used, it has the disadvantage that correction of electrical length, phase, etc. is required.

The present invention solves the above-mentioned conventional drawbacks by eliminating the 60Ω or 75Ω coaxial cable 13 and configuring the VIP filter section inside the tuner, thereby realizing miniaturization and economy, thereby making it possible to reduce costs. The purpose is to

A broadband reception tuner according to an embodiment of the present invention will be explained using FIG.

1 is an input terminal of the tuner, which is a connector terminal of about 76Ω. 2 is an input filter circuit section, which includes a switching circuit,
Low pass filter (HPF), low pass filter (L
PF) and bandstop filter (BSF) circuit, and the insertion loss is 0.7 to 1 within the band.
．． □It is about 6B.

Reference numeral 3 denotes a wideband variable attenuator, to which an appropriate voltage is externally supplied to the GC terminal 16 in order to maintain the signal from the input filter circuit section 2 at an appropriate level. Insertion loss is 0.
It is about 8 to 1.2 dB. Reference numeral 4 denotes a wideband amplifier, which amplifies the signal from the wideband variable attenuator 3 to an appropriate level. Normally, in a tuner with this configuration, it is necessary to obtain a noise figure (NF) of 13 to 2.
A gain of about 0 is required, and the NF of this broadband amplifier 4 is also set at about 2.0 to 3 degrees OdBdB. 6 is a first mixer that mixes the signal from the wideband amplifier 4 and the signal from the voltage controlled oscillator (VCO) 7 to extract a first intermediate frequency signal of 2.5 GHz band or higher, with a conversion loss of about 7 dB. It is. 1% 0ros
The ts Modulation level is set according to specifications, and is capable of achieving a 0M value of about 116 dBμV. 6 is a buffer amplifier and a signal amplifier of the voltage controlled oscillator 7. 8 is a band transducer for passing the first intermediate frequency signal and removing unnecessary signals, and has a bandwidth of 6 MHz + insertion loss of about 6° dB. 9 is a second mixer, which mixes the first intermediate frequency signal from the band p-wave generator 8 and the signal from the fixed oscillator 10 and converts it into a second intermediate frequency (standard intermediate frequency) signal, which converts tM
The loss is about 6dB, and the cross modulation is 1%
on (CM) Level can be set according to specifications.

11 is a second intermediate frequency amplifier (standard intermediate frequency amplifier)
It is. For example, the standard intermediate frequency is the 58 MH2 band in the case of the Japanese channel.

The present invention includes a VIP filter section 22 in the wideband tuner 17.
It is distinctive in that it has a 2o is SAY filter,
This is a VIP filter circuit using a bulk filter, a pisonator, a trap filter, etc. Reference numeral 21 denotes an amplifier for maintaining the output level of the VIP filter section 22 at an appropriate level.

Reference numeral 23 denotes an output end of the VIF filter section, which can be a balanced or unbalanced end depending on the input circuit at the subsequent stage. Figure 3 shows the frequency characteristics when using a SAW filter on the Japanese channel, showing the video intermediate frequency of 58
．． 75MHz + audio intermediate frequency 5'4, 25 MH
z + color sub gear 9 frequency 55.1'y MH7 and receiving channel video intermediate frequency 58.75 MH2 1. The frequency attenuation characteristic of the audio intermediate frequency of 60.25 MH2, etc. of the lower adjacent channel which is sMHz apart is taken into consideration, and is designed to have a peak characteristic at 57 MH2. It goes without saying that such attenuation characteristics may be changed as appropriate depending on the specifications.

In this embodiment, the intermediate frequency amplifier 1 inside the tuner section 17
By arranging the VIP filter section 22 after 1, the conventional 6oΩ or 75Ω coaxial cable and its input/output connectors that connect the tuner section and the VIP filter section can be removed, resulting in smaller size and lower cost. It has the advantage of being possible. Furthermore, since no coaxial cable is used, there is no need for circuits for correcting electrical length and phase, so a compact and economical tuner can be realized.

FIG. 4 shows the intermediate frequency amplifier 11 and V after the second mixer 9.
This is another embodiment of the IP filter section 22.

Identical symbols have the same functions and will therefore be omitted. The embodiment shown in FIG. 4a includes a second mixer 9 and an intermediate frequency amplifier 1.
In addition to the advantages of the embodiment shown in FIG. 2, it is possible to attenuate interfering signals other than the receiving channel. However, in the embodiment shown in FIG. 4, a VIP filter 20 is configured after the second mixer 9, and VIP amplifiers 21 and 26 are connected in cascade, and the output level at the output terminal of 23 is adjusted to an appropriate level. The VIP filter section 22 is composed of the VIP filter 20 and the VIP amplifiers 21 and 26. In this way, the VIP is placed after the second mixer.
By configuring the filter 2o, in addition to the advantages of the embodiment shown in FIG. 2, it is possible to maintain the signal of the receiving channel at an appropriate level, so that it has the advantage of reducing distortion generated in the VIP amplifiers 21 and 26 in the subsequent stage. It is something.

In this way, as shown in the circuit configurations of FIGS. 2 and 4, (, V
By configuring the IP filter unit 22 inside the broadband reception tuner, the conventionally used 6oΩ or 76Ω coaxial cable 13 can be removed, and at the same time, the tuner output connector 12. Since the VIP filter input connector 12' can be omitted, costs can be reduced and miniaturization and economy can be realized. Furthermore, since there is no need to consider correction of electrical length, phase, etc. due to the coaxial cape M, it has the advantage that a clearer image can be realized. In the embodiments of the present invention, a double-mixing broadband reception tuner has been described, but the present invention is not limited thereto, and can be applied to tuners commonly used in the past.

As described above, the present invention is a wideband reception tuner having at least one mixer, in which a video intermediate frequency (VIP) filter section is built into the downstream side of the mixer, which is different from the conventional method. It is possible to eliminate the 6oΩ or 76Ω coaxial cable, and at the same time, reduce the output connector of the conventional tuner and the VIP filter input connector, so it is possible to lower the price, and it is possible to realize miniaturization and economy. , there is no need to consider corrections such as electrical length and phase due to the use of a coaxial cable, so it has the advantage of realizing a clearer image.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional wideband reception tuner and VIP filter section, Fig. 2 is a block diagram of an embodiment of the wideband reception tuner of the present invention, and Fig. 3 is a frequency attenuation characteristic diagram of the VIP filter circuit of the present invention. , FIGS. 4a and 4b show another embodiment of the broadband reception tuner of the present invention, which includes a frequency amplification circuit,
FIG. 2 is a block diagram showing a VIP filter section. 1...Tuner input terminal, 2...Input filter circuit section, 3...Broadband variable attenuator, 4
...Broadband amplifier, 6...First mixer, 6...Buffer amplifier, 7...Voltage controlled oscillator (VCO), 8...・・Band filter, 9・・
...Second mixer, 1o...Fixed oscillator (F
XO), 11... intermediate frequency amplifier, 12...
...Tuner output terminal (connector) 13...
Coaxial cable, 12'...VIP filter input connector, 14.22...VIP filter section,
16...VIF filter section output output signal 6...
...MuGC terminal, 20..., VIP filter circuit, 21.26...VIP amplifier, 23...
...VIF filter section output end, 24...IP
filter circuit.

Claims (3)

[Claims] (1) A wideband reception tuner comprising at least one mixer, and a video intermediate frequency filter section provided between the mixer and an output terminal. (2) The wideband receiving tuner according to claim 1, wherein the video intermediate frequency filter section comprises a filter circuit and one or more O amplifiers. (3) Wideband reception according to claim 1 or 2, characterized in that an intermediate frequency filter circuit is provided between the mixer provided at the last stage and the video intermediate frequency filter section. tuner.