JPH0145157Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a high frequency resistance attenuator using a resistor having a resistive thin film layer formed on its surface.

[Background technology and its problems]

A simple resistance attenuator can be made by soldering a rod-shaped resistor to a conductive pattern formed on a printed wiring board.

FIG. 1 shows an example of such a resistance attenuator, in which R ₁ , R ₂ , and R ₃ are rod-shaped resistors with conductive caps for electrodes at both ends, respectively, and P ₁ ,
P ₂ is a signal input conductor and a signal output conductor which are signal input and output conductors, and P ₃ is a ground conductor.

In this case, the resistors R ₁ , R ₂ , and R ₃ constitute a π-shaped attenuator, but when measuring the frequency characteristics of this resistive attenuator, it generally shows as shown by the solid line in Figure 2. Attenuation decreases in high frequency range.

Various factors can be considered as the cause of this decrease in attenuation, but generally it is largely due to the influence of the strain capacitance Cs shown by the dotted line that is present in parallel with the resistor _R1 .

Therefore, in order to compensate for the decrease in attenuation in the high frequency range due to the influence of this stray capacitance Cs, a compensating capacitor C _E is required as shown by the dashed line.
It would be possible to add a capacitor, but its capacity would be small, less than 0.5PF, making installation difficult.

Another method is to cover the resistors R ₂ and R ₃ with metal pipes, but this method is time-consuming and does not give good results.

[Purpose of invention]

This invention was made to solve this problem, and is a high-frequency resistive attenuator that can compensate for the decrease in attenuation at high frequencies by making simple modifications to the printed wiring board. It is also something that provides.

〔Example〕

An embodiment of the high frequency resistive attenuator of this invention will be described below with reference to FIGS. 3a and 3b.

In these figures, P ₁ is the signal input conductor to which the input signal is supplied, P ₂ is the signal output conductor,
P ₃ is the earth conductor. Resistor as in Figure 1
R ₁ , R ₂ , and R ₃ are connected across these conductors to form a π-shaped resistance attenuator, and the cap portions of the second and third resistors R ₂ and R ₃
There is a hole H in the part of the printed wiring board where C ₁ and C ₂ touch.
is provided. Furthermore, the second and third resistors
An earth conductor P _E was formed at a position where R ₂ and R ₃ are opposed to each other. Therefore, in the high frequency resistance attenuator of this invention, as can be understood from the side view of FIG.
The third resistors R ₂ and R ₃ can be fixed in close contact with the earth conductor PE electrically connected to the earth conductor _{P 3} .

Therefore, in this resistive attenuator, ground capacitance Ce is equivalently added as shown in Figure 4, and compensation is made so that the attenuation does not decrease in the high frequency range as shown by the dotted line in Figure 2. can do.

Figure 5 shows another embodiment of this invention.
The same parts as in FIG. 3 are given the same reference numerals.

However, in this embodiment, the second and third resistors
Since R ₂ and R ₃ are configured so that they are grounded in directions 180° different from each other, the influence of the strain capacity Cs shown in Figure 1 is reduced, and the attenuation remains flat even in the higher frequency range. It can be done.

In addition, if the cap parts C ₁ and C ₂ are directly soldered to the conductors P ₁ , P ₂ , and P ₃ of the printed wiring board as shown in the figure, the residual inductance component due to the lead wires will be reduced, and the inductance will remain constant even at high frequencies. Attenuation amount can be secured.

[Effect of idea]

As explained above, the high-frequency resistance attenuator of this invention is extremely simple because it forms a compensating capacitor by providing a hole in the printed wiring board that is small enough for the bulge of the resistor cap to sink into. This has the great effect of ensuring the amount of attenuation up to a high frequency range.

[Brief explanation of the drawing]

Figure 1 is a plan view of a resistive attenuator formed on a printed wiring board, Figure 2 is a diagram showing the frequency characteristics of the resistive attenuator, and Figures 3 a and b are resistive attenuators showing one embodiment of this invention. Top view and side view of the vessel, Figure 4 is the 3rd
Figure a is an equivalent circuit diagram, and Figure 5 is a resistor layout diagram showing another embodiment of this invention. In the figure, R ₁ , R ₂ , and R ₃ are the first, second, and third resistors, C ₁ and C ₂ are the cap parts, H is the hole, and P ₁ and P ₂ are the signal input and output conductors. , P ₃ , P _E indicate the earth conductor.

Claims (1)

[Scope of utility model registration request] a first resistor connected between a printed wiring board and a signal input conductor and a signal output conductor formed on the printed wiring board, one end of which is connected to each end of the first resistor; In the high frequency resistance attenuator, the second and third resistors are connected to each other and the other ends are connected to a ground conductor formed on the printed wiring board. A hole is provided for sinking the cap portion of the resistor No. 3 into the printed wiring board, and a hole is provided for sinking the cap portion of the resistor No. 3 into the printed wiring board.
and a high frequency resistance attenuator, characterized in that a ground conductor P _E electrically connected to the ground conductor is formed at a location facing the third resistor.