JPH01106633A - Tuner circuit for satellite broadcast television receiver - Google Patents

Abstract

PURPOSE:To simplify the adjustment by patterning an inductor of a pre-selector circuit onto a printed circuit board and providing a wire for coupling and adjustment of input/output of a signal to inter-stage. CONSTITUTION:A pre-selector circuit 6 of a tuner circuit is formed by patterning directly a primary inductor 21, a secondary inductor 25, an image trapping inductor 28, and an inductor 50 to input a local oscillation signal directly onto the printed circuit board. In the circuit 6 as above, the frequency of an image wave depends on the inductance of the inductor 28 and the capacitance between the inductors 21 and 28. Then in the mixer circuit 7 also, inductors 30, 43, 44 are formed by being pattern directly onto the printed circuit board. In the circuits 6, 7 of the constitution above, wires 47, 48 are provided for coupling adjustment of input/output of a signal to/from inter-stage. Thus, the coupling between the primary and secondary sides require no adjustment and the coupling adjustment of the input/output of the signal to/from the inter-stage is implemented by having only to move the wires 47, 48.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a tuner circuit for a satellite television receiver.

"Prior Art" Generally, a satellite broadcast television receiver has a tuner circuit as an adapter connected to the front stage of a normal terrestrial broadcast television receiver.

To explain this tuner circuit, when a parabolic antenna receives satellite broadcasting signals in the IIG)Iz band and 4G&
This first IF multiplied signal is amplified by the RF amplification circuit, and the preselector circuit selects a signal with a predetermined frequency and sends it to the mixer circuit. mixed with a local oscillator signal, 134.
Obtain the second intermediate frequency (IF) signal of 26M1 (z, amplify it with an amplifier circuit, and then pass it through a low-pass filter (LPF).
After passing through the circuit, it is further amplified by an amplifier circuit and sent to the demodulation circuit of a normal television receiver.

As shown in FIG. 3, the preselector circuit in the satellite television receiver described above transmits the signal from the RF amplifier circuit to the primary inductor (21) (28) via the coupling capacitor (20). supply, and also a bonding window (22
) through a shield plate (23) with a coupling loop (2
4), a local oscillation signal is mixed from the mixer circuit, and a second IF signal is obtained from the secondary inductor (25). (
26) (27) is a variable capacitance diode whose capacitance is variable depending on the tuning voltage. The inductors of such preselector circuits and mixer circuits, which consist of double-tuned circuits, are formed by punching out copper plates, as shown in Figure 4, and are not only shaped like a simple U-shape, but also have adjustment protrusions with complex shapes. The image trap was mainly adjusted by moving the coupling loop between the secondary inductor and the shield plate.

``Problems to be solved by the invention'' However, inductors made of conventional copper plates not only have a complicated structure, but also have extremely poor workability because adjustment of the adjustment protrusions and coupling loops is done in a narrow space. I was spending a lot of time.

In addition, there are variations due to adjustment, fluctuations due to vibration, and drift of adjustment points due to temperature changes, which are inconvenient in maintaining product quality. Furthermore, characteristics were affected by lifting of the inductor and coupling loop when soldered, making assembly difficult.

"Means for Solving the Problems" The present invention has been made to achieve the above-mentioned object, and after converting the satellite broadcasting signal received by the parabolic antenna into the first IF signal using the converter, A circuit in which a signal of a predetermined frequency is selected by a selector circuit, a local oscillation signal is mixed with this signal by a mixer circuit, the signal is converted into a second IF multiplied signal, and the signal is transmitted to a normal television receiver. The preselector is formed by forming the primary and secondary inductors that constitute a double-tuned circuit on a printed circuit board using a microstrip line, and facing the primary inductor from the capacitor and the inductor formed by the pattern. In addition, a coupling loop using the mixer circuit pattern is provided facing the secondary inductor.

Wires for adjusting the degree of coupling are provided between the primary inductor and the image trap inductor and between the secondary inductor and the coupling loop of the mixer circuit.

"Operation" When receiving satellite broadcasting signals in the 11GHz band and 4GHz band with a parabolic antenna, the converter receives 950~1450M
The first IF multiplied signal of Hz is converted, and the second IF multiplied signal of 134.26MH7 is obtained by a mixer circuit. This signal is amplified by the second IF amplifier circuit and sent as a signal to the demodulation circuit of a normal television receiver. The inductors of the preselector circuit are all formed by patterning on a printed circuit board, so that adjustment of the primary side and the secondary side is not required. In addition, the coupling adjustment of signal input and output between stages is
Adjustments can be made by simply moving the wire from side to side, and after adjustment, it is fixed with wax.

"Example" Hereinafter, one embodiment of the present invention will be described based on the drawings.

In FIG. 2, (1) is a parabolic antenna, and this parabolic antenna (1) is coupled to an input terminal (4) of a tuner circuit (3) via a converter (2). This input terminal (4) is the 11th. F amplifier circuit (5).

It is coupled to a mixer circuit (7) via a preselector circuit (6), and a local signal oscillation circuit (8) and an oscillation signal amplification circuit (9) are coupled to this mixer circuit (7). The output side of this mixer circuit (7) is connected to an output terminal ( 14) are combined. In addition, the second
Automatic gain control (AG) is used in the first stage amplifier circuit (11) for IF.
C) The circuit (10) is coupled. A second IF signal (134, 26M
)lz) is coupled with a sufficient frequency circuit (15) for detecting deviation.

The preselector circuit (6), as shown in FIG.
A primary inductor (21), a secondary inductor (25), and a resonant line (
29), an image trap inductor (28) facing the primary inductor (21), and an inductor (30) for inputting a local oscillation signal facing the secondary inductor (25) on a printed circuit board. An RF signal input terminal (31) is connected to one end of the primary inductor (21) via a coupling capacitor (20). In addition.

(32) (33) is a variable capacitance diode, (34) is a tuning voltage input terminal, (35) (36) (37) (
38) (39) is a capacitor, (40) and (41) are resistors, and (42) is an inductor.

In such a preselector circuit (6), the frequency of the image wave is determined by the inductance of the inductor (28) and the capacitance between the two inductors (21) (2g). In addition, two inductors (21)
When the degree of coupling between (28) and (25) and (30) is weak, a capacitor is inserted between each.

Next, also in the mixer circuit (7) of FIG. 1, the inductors (30), (43), and (44) are formed directly on the printed circuit board by patterning. (45) is a local oscillation input terminal, and (46) is an output terminal.

In the preselector circuit (6) and mixer circuit (7) configured as described above, a wire (47) coated with urethane or the like is used to adjust the coupling of input and output signals between stages.
48) is provided. One end of one wire (47) is 1
This wire (4) is connected to one end of the next inductor (21).
The other end of 7) faces above the image trap inductor (28) in a state where it can move left and right.

Similarly, one end of the other wire (48) is connected to one end of the secondary inductor (25), and the other end of this wire (48) is connected to the implant of the mixer circuit (7) in a state where it can move left and right. make it appear on top of These wires (47) (
48) are adjusted by moving them left and right, and after adjustment.

Fix with wax (49) (5G).

Next, the present invention will be explained in detail.

When the parabolic antenna (1) receives satellite broadcast signals in the 11 GHz band and 4 GHz band, the converter (2) converts the 95
It is converted into a first intermediate frequency (IF) signal in the 0 to 1450 MHz band and input to the input terminal (4) of the tuner circuit (3). The first IF multiplied signal input to this input terminal (4) is amplified by the first IF amplifier circuit (5), a preselector circuit (6) selects a predetermined frequency, and the signal is sent to the mixer circuit (7). This mixer circuit (7) mixes the local oscillation signal sent via the oscillation circuit (8) and the oscillation signal amplification circuit (9), and generates a second intermediate frequency (I) of 134.26MHz.
F) A signal is output. This second IF multiplied signal is amplified by the first stage amplifier circuit (11) for the first IF.
The gain is controlled to a predetermined value by the AGC voltage from the C circuit (10). After that, a low-pass filter (LPF) circuit (12
) and is amplified by a two-stage amplifier circuit (13) for the second IF, and this second IF multiplied signal of 134.26 MHz is sent to the demodulation circuit of a normal television receiver via the output terminal (14).

"Effects of the Invention" Since the present invention is configured as described above, there is no need to adjust the coupling between the primary and secondary inductors, and only the coupling adjustment of signal input and output between stages is required. It can be adjusted extremely easily by simply moving it. Therefore, we can provide a high-quality tuner circuit, and there are no assembly problems.
It is possible to reduce costs by eliminating parts.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an embodiment of the preselect circuit and mixer circuit in the tuner circuit according to the present invention, FIG. 2 is a block diagram of the tuner circuit of a satellite broadcast television receiver, and FIG. The selection circuit diagram, FIG. 4 is a perspective view of the same as above. (1) Parabolic antenna, (2) Converter, (3) Tuner circuit, (4) Input terminal, (5) Amplifier circuit, (6)・Preselector circuit, (7)...Mixer circuit, (8)...Oscillation circuit, (9)...Oscillation signal amplification circuit, (10)...AG
C circuit, (11)...first stage amplifier circuit for second IF, (
12)...LPF circuit, (13)...2 for second IF
Stage amplifier circuit, (14)...output terminal, (21) (2
5) (28) (30)... Inductor by patterning, (32) (33)... Variable capacitance diode, (47) (48)... Wire, (49) (50)
...Deaf. Applicant: Fujitsu General Niyo J Co., Ltd. Part 3, Figure 4

Claims (2)

[Claims] (1) After the satellite broadcasting signal received by the parabolic antenna is converted into the first IF signal by the converter, a preselector circuit selects a signal of a predetermined frequency, and a local oscillation signal is mixed with this signal by the mixer circuit. In this circuit, the preselector converts the signal into a second IF signal and transmits it to a normal television receiver. An image trap consisting of a capacitor and an inductor formed by the pattern is formed by forming a pattern on the substrate, facing the primary side inductor, and a coupling loop formed by the pattern of the mixer circuit is provided facing the secondary side inductor. and a wire for adjusting the degree of coupling is provided between the primary inductor and the image trap inductor and between the secondary inductor and the coupling loop of the mixer circuit. Tuner circuit for broadcast television receiver. (2) The wire for adjusting the degree of bonding is obtained by connecting one end of the wire coated with an insulating material to one inductor, and fixing the other end of the wire with wax after adjusting the degree of bonding. A tuner circuit for a satellite television receiver described in Section 1.