JPS6322695Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the wiring structure of a printed circuit board, and more specifically, the present invention relates to a wiring structure of a printed circuit board, and more specifically, a single return terminal of an integrated circuit unbalanced amplifier mounted on the board is provided outside the board. The present invention relates to a printed circuit board in which a plurality of paths for connecting to a return terminal of an external circuit are printed and wired on the board.

Referring to FIG. 1, the prior art will be described. A single return terminal 3 of an integrated circuit unbalanced amplifier 2 mounted on a substrate 1 is connected to an external circuit 4 provided outside the substrate 1. A single path 5 for carrying the return current is printed on the substrate 1. The external circuit 4 includes an input signal source 6 that provides an input signal to the unbalanced amplifier 2, a driven circuit 7 driven by the unbalanced amplifier 2, a power supply (not shown), and the like. Therefore, the path 5 is a common path for the input signal source 6, the driven circuit 7, etc., and if the impedance of this common path is Z0, it is represented by the equivalent circuit shown in FIG. Since the thickness of the path 5, which is a printed wiring, is small, it has an impedance, and if the impedance of this path 5 is Z1, then Z0=Z1. This impedance Z1 is
Since it is inserted between the unbalanced amplifier 2, the input signal source 6 and the driven circuit 7, the output of the unbalanced amplifier is connected to the voltage dividing circuit formed by the driven circuit 7 and Z1 and the input signal source 6.
It is returned to the input side via. Furthermore, when connecting the external circuit 4 to a circuit such as the unbalanced amplifier 2 mounted on the board 1 using a connector (not shown),
Contact resistance occurs between the metal piece of the connector and the printed wiring. If the contact resistance between the metal piece of the connector and the return path 5 is Z2, then Z0 = Z1 + Z2, and the return is applied even more. Therefore, when the unbalanced amplifier 2 has a high gain and the feedback is positive feedback, this becomes a particular problem, and distortion characteristics, frequency characteristics, stability, etc. deteriorate, and sometimes oscillation may occur. In order to solve such problems, proposals have been made to consider the arrangement of components mounted on the board 1, to widen the width of the path 5, or to shorten the path 5. Furthermore, when using a connector, it has been proposed to allocate a plurality of terminals of the connector to the path 5 to reduce contact resistance. Although such proposals are effective, it is often difficult to implement such proposals in terms of component placement and the like.

The purpose of this invention is to solve the above technical problems,
It is an object of the present invention to provide a printed circuit board that eliminates common paths as much as possible.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a front view of one embodiment of the present invention. An integrated unbalanced amplifier 12 and components or circuits (not shown) are mounted on the substrate 11. The unbalanced amplifier 12 is formed into a 14-pin structure of a dual in-line package, and has a return terminal 13, an input terminal, an output terminal, a power supply terminal, and other terminals. An external circuit 14 is provided outside the substrate 11 . The external circuit 14 includes an input signal source 1 that provides an input signal to the unbalanced amplifier 12.
5, a driven circuit 16 driven by the unbalanced amplifier 12, a power source that supplies power to the unbalanced amplifier 12, and the like.

A plurality of (two shown in the figure) routes 17 and 18 branching from the vicinity of the return terminal 13 are printed on the board 11 . These paths 17 and 18 are connected to the external circuit 14
This is a line for connecting the return terminal 13, and different paths are assigned to at least the input signal source 15 and the driven circuit 16. That is, the input signal source 15 is assigned a path 17 and the driven circuit 16 is assigned a path 18. Route 18
is also assigned to the power supply.

Input signal source 15 is connected to the input terminal of unbalanced amplifier 12 via printed wiring 19 . Driven circuit 16 is connected to the output terminal of unbalanced amplifier 12 via printed wiring 20 . Components and circuits mounted on the board 11 and electrically related to the unbalanced amplifier 12 are connected to a printed wiring 21 that branches off from the middle of the path 17 .

The impedance of the path 17 or the impedance including the contact resistance between the path 17 and the connector.
When Z3 is the impedance of the path 18 or the impedance including the contact resistance between the path 18 and the connector is Z4, the equivalent circuit shown in FIG. 4 is shown. Route 17 and route 18 are connected to return terminal 13
Route 17 and Route 18 are branched nearby.
common routes are eliminated as much as possible. Therefore, impedances Z3 and Z4 are outside the common path,
Accordingly, coupling between input and output signals is prevented.
Therefore, distortion rate characteristics, frequency characteristics, stability, etc. are prevented from deteriorating due to undesired feedback.
Furthermore, the degree of freedom in designing component placement is improved.

FIG. 5 is a front view of another embodiment of the present invention, and parts corresponding to the embodiment shown in FIG. 3 are given the same reference numerals. What should be noted is that a route 22 is provided in addition to routes 17 and 18. The route 22 is
It is assigned to the input signal source 15, the driven circuit 16, and the external circuit 14 other than the power supply. Therefore, power supply ripples and mixing of signals from other circuits sharing the power supply are prevented.

FIG. 6 is a front view of another embodiment of the present invention, and parts corresponding to the embodiments shown in FIGS. 3 and 5 are given the same reference numerals. What should be noted is that the path 18, which was previously allocated to the driven circuit 16 and the power source, is now exclusively allocated to the driven circuit 16, and the path 23 is allocated to the power source. Therefore, interference with other circuits via the power supply can be prevented.

FIG. 7 is a front view of another embodiment of the present invention, and parts corresponding to the embodiments shown in FIGS. 3, 5, and 6 are given the same reference numerals. It should be noted that between each path 17, 18, 22, 23, a foil-free strip 24, 25, 26 having a small width is provided. Therefore, each route 17, 18, 2
2, 23 becomes wider, and each route 17, 1
8, 22, and 23 can be lowered. Also, the pattern can be simplified.

In other embodiments of the present invention, paths may be provided on both sides of the substrate.

As described above, according to the present invention, since the common path through which the return current flows is eliminated as much as possible, coupling of signals from external circuits is prevented. In addition, since different paths are assigned to at least two of the input signal source and the driven circuit, coupling between the input signal and the output signal is prevented, harmful feedback is not applied, and distortion characteristics and frequency characteristics are , stability, etc. are prevented from deteriorating. Further, since there is no need to unnecessarily widen or shorten the path, the degree of freedom in design, such as the arrangement of components on the board, is improved. Further, when a foil-free band having a small width is provided, the impedance of each path can be lowered and the pattern can be simplified. Furthermore, even when a connector is interposed between the board and the external circuit, the above-mentioned effects are not impaired.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the prior art, Fig. 2 is a diagram showing its equivalent circuit, Fig. 3 is a front view of an embodiment of the present invention, Fig. 4 is a diagram showing its equivalent circuit, and Fig. 5 is a diagram showing its equivalent circuit. FIG. 6 is a front view of another embodiment of the present invention, and FIG. 7 is a front view of another embodiment of the present invention. 11... Board, 12... Unbalanced amplifier, 13...
... Return terminal, 14 ... External circuit, 15 ... Input signal source, 16 ... Driven circuit, 17, 18, 22,
23... Route, 19, 20, 21... Printed wiring, 24, 25, 26... Non-foil strip.

Claims (1)

[Claims for Utility Model Registration] (1) A method for connecting a single return terminal of an unbalanced amplifier integrated circuit mounted on a board and a return terminal of an external circuit provided outside the board. A printed circuit board, characterized in that a plurality of paths are printed on the board, and each path is branched from near a return terminal of the unbalanced amplifier. (2) At least two of the external circuit, an input signal source that provides an input signal to the unbalanced amplifier, and a driven circuit driven by the unbalanced amplifier are connected to different paths of the respective paths. The printed circuit board according to claim 1, wherein a route is assigned. (3) The printed circuit board according to claim 1 or 2, wherein a foil-free band having a slight width is provided between each of the paths.