JPS6178193A - High frequency amplification circuit for tv tunner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] The present invention is a printed circuit board! This invention relates to a high frequency amplification circuit for a television set using a surface-mounted chip type dual gate MO8FZT as an amplification element.

In recent years, the use of high-frequency circuit elements as chips has been rapidly progressing, and chips have been widely used in television televisions for the purpose of miniaturization, high-density packaging, and high performance. However, with the miniaturization of components, shortcomings in high frequency characteristics due to their mounting are becoming increasingly obvious. Hereinafter, the drawbacks of the conventional example will be explained with reference to FIG.

Figure 2 (a) is a chip type dual gate MO8FKT1
In the conventional implementation example, 2 is the drain, 3 is the first gate, and 4 is the drain.
5 indicates the second gate electrode, and 5 indicates the source electrode. This conventional example is an example of implementation in a relatively low frequency band of 50 MHz or less, but it has problems as described below. That is, since it is a chip component, the spatial distance between the first gate 3 on the signal input side and the drain 2 on the output side is very small, so unnecessary transmission amount occurs through space and the substrate.
The value becomes so large that it cannot be ignored. Particularly in television tuners, since the high-frequency amplification circuit constitutes the gain control loop of the television set, this problem greatly reduces the maximum gain control amount and causes image quality deterioration such as image disturbance in areas with strong electric fields. become the cause.

FIG. 2(b) shows a conventional example intended to improve this problem, in which 6.7 is an earth round and 8.9 is a chip capacitor for grounding. However, the grounding effect of this conventional grounding capacitor 8.9 is from VHP low band to VHP
It is insufficient to satisfy up to the obi. Therefore, the conductive pattern wired on the bottom surface of the chip-type dual gate MOSFET 1 cannot be at a complete ground potential as shown in the equivalent circuit of FIG. A bond remains between them. As described above, the pattern arrangement of the conventional example shown in FIG. 2(B) cannot improve the good characteristics of the isolation 1, and it cannot be expected to significantly improve the maximum gain control amount.

The present invention is intended to solve this problem, and is capable of perfecting AGC operation in areas with strong electric fields in a television lan tuner using a chip type dual game (MO8I'ET) as an amplification element of a high frequency amplification circuit. It was carried out in
It is an object of the present invention to provide a high frequency amplification circuit that can produce images with good image quality.

[Structure of the Invention] The high frequency amplification circuit of the television receiver of the present invention is a chip-type DAIRG MO8FI! i
In a television launch system in which T is an amplifier element of a high frequency amplifier circuit, the chip F MO8F1! is mounted on a printed circuit board. :A conductive pattern is provided between the opposing first gate and drain electrodes of T, and this conductive pattern is connected to the chip-type MO81'l! : It is characterized by extending in the direction of both sides of the T without electrodes and connecting this to the earth round provided in the direction of extension.

An embodiment of the invention will be described with reference to FIG.

In the same figure, 1 is a chip type deaial gate MO8FET.
, 2 is the drain, 5 is the first gate, 4 is the second gate, 5
is the source. Reference numeral 10 denotes a conductive pattern provided between the first gate 3 and the second gate 4 and the drain 2 and the drain 75 facing each other, which extends in the direction of both sides of the chip type MOFICT 1 without electrodes, and is connected to the wiring. It is connected to the ground round 11.12 provided on the board.

[Effect of the invention] As described above, in the present invention,
A conductive pattern 10 is provided between the first gate 5 and the second gate 4 and the opposing drain 2 and source 5, and both ends thereof are connected to the ground round 11.121C.
Therefore, the distance between the first gate 3 and the drain 2 is shown in FIG. 5Cb).
As shown in the equivalent circuit of , it can be completely grounded. Therefore, the amount of transmission from the first gate round to the drain round and the gain control amount of the high frequency amplification circuit can be greatly improved as shown in FIGS. 4 and 5. In addition, in Fig. 4 and Fig. 5, (
(a) shows the conventional example in FIG. 2 (a), (b) shows the conventional example in FIG. 2 (b), and (c) shows the characteristics of the present invention.

Furthermore, the present invention is a chip-type device (Alge) 14087F.
It also has the advantage of greatly reducing electrical connections between rounds when iτ is placed on a printed circuit board.

[Brief explanation of drawings]

Figure 1: Chip type dual gate MO8FKT of the present invention
Example of mounting on a printed circuit board Figure 2: Example of mounting 'r on a printed circuit board of (4140)ti conventional chip type DEAL gate MO87 Figure 3:
Chip type deaial gate MOEI? ]! :Equivalent circuit diagram between the first gate and drain of T, (α) is the conventional example, Cb) is the transmission f (relative Figure 4 shows the gain control amount (300MHz) of the high frequency amplification circuit by MO81'FXT. 2...Drain, 3...First gate, 4...Second
Gate, 5... Source, 6.7... Earth round, 8.9... Ground capacitor, 10... Conductive pattern, Figure 1 Figure 2 (0) (MHz
) Procedural amendment (method) Date of February 1985 t Indication of case 1988 Patent Application No. 200044 2 Title of invention High frequency amplification circuit for television tuner Applicant 582 Matsushita Electric Industrial Co., Ltd. 4, Agent

Claims (1)

[Claims] In a television tuner using a chip-type dual-gate MOSFET as an amplification element of a high-frequency amplification circuit, a conductive pattern is provided between two opposing electrodes of a first gate and a drain of the chip-type MOSFET mounted on a printed circuit board. , this conductive pattern is connected to the chip type MOSFET.
A high frequency amplification circuit for a television tuner, characterized in that the T is extended in the direction of both sides without electrodes, and connected to a ground round provided in the direction of the extension.