JPS6019647B2 - transformer circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wideband transformer circuit used in various communication devices, and more particularly to a transformer circuit that greatly improves the amount of mismatch attenuation in the passband.

Transformers used in communication equipment must have flat and small operating attenuation characteristics within the band of use, and must have good impedance matching with the signal source and load resistance to reduce the effects of reflected waves. A large matching attenuation characteristic is required. This is particularly important for devices whose primary purpose is waveform transmission. Furthermore, it is desirable that the device be mechanically small. Conventionally, it has been known that in order to realize such a transformer, it is sufficient to use a magnetic core with a large relative magnetic permeability.

However, there is a limit to the realization of a magnetic core with a large relative magnetic permeability, and in reality, as the relative magnetic permeability increases, the instability of the magnetic core increases, and there are various restrictions on use. Further, when a direct current flows through the winding and a direct current magnetizing force is applied, the relative magnetic permeability is further restricted in terms of saturation magnetic flux density. Therefore, in order to realize a transformer that is small and has a large amount of mismatch attenuation, it is necessary to wind the pongee wire many times, but this increases the DC resistance due to the winding, which affects the electrical characteristics. This will lead to the deterioration of An object of the present invention is to provide a transformer circuit with good mismatched attenuation, which eliminates the above-mentioned drawbacks.

The transformer of the present invention includes a metal foil inserted between the primary winding and the secondary winding for electrostatic shielding, and a resistor having a resistance value that substantially satisfies a predetermined condition between the terminals of the electrostatic shield. It is characterized by the fact that it followed.

As a result, we were able to improve the mismatch attenuation by making the operating attenuation a little more uniform. Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a circuit diagram of a conventional transformer with an electrostatic shield to reduce longitudinal current. In the figure, a primary winding 2 and a secondary winding 3 are wound around the center 1, and a metal foil is wound between the primary winding 2 and the secondary winding 3. An electrostatic shield 4 is formed to reduce electrostatic coupling between the side winding 2 and the secondary winding 3. One end 5 of this shield 4 is grounded, and both terminals T and T of the primary winding 2 are connected to the ground.
' is connected to a signal source 6 having an internal resistance R, and a load 7 having a resistance value R2 is connected to terminals L and T2' on both sides of the secondary winding 3. FIG. 2 is a circuit diagram showing one embodiment of the present invention.

In the figure, the transformer 12 has a primary winding 2, a secondary winding 3, an electrostatic shield 4 formed between these primary and secondary windings, and an opposite ground end 9 of the shield 4. A resistor 11 having a resistance value R3 is connected between the side end 10 and ground. In the transformer 8 as shown in FIG. The transformer 8 in FIG. 1 can be expressed as shown in FIG. 4a, and generally (R2/R,
)=n2. The circuit shown in figure a can be expressed as an equivalent circuit as shown in figure b in the middle castle of the passage zone. In the same figure b, terminals T, -T,
The impedance Zin when looking at the transformer side from ' is Zin=
y, 10y2/n20R2/〆=y, 10y2/〆10R.

The matching state of impedance when looking at the transformer side when the internal resistance R of the signal source 6 is referenced, that is, the mismatch attenuation R
Shiha RL = 2 mark.

It is expressed as g1Kamesanki.

Substituting Zin in the above formula, R: 2m increase 1 Toyosantei main rod voice/poison ≧ Tatsumate 1: increase 1 wave 1
;． Main 1 tea poison 21 = 2 melons.

g{y, rare 2'nM}■. ...[1] becomes. As is clear from this equation, the mismatch attenuation RL is governed by the DC resistances y and y2 of the primary winding 2 and the secondary winding 3, respectively. In Figure 2, the DC resistance of the primary winding 2 is y, the DC resistance of the secondary winding 3 is y2, and the electrostatic shield 4 is
Let the DC resistance between terminals 9 and 10 be 3 and the low resistance value of the resistor 11 connected to the electrostatic shield 4 be R3.
When the number of turns of the secondary winding 2 is n, the number of turns of the secondary winding 3 is -, and the number of turns of the electrostatic shield is 1, the turns ratio (n, / mountain) 2 = R. /R2 between the terminals T, , T,' and between T2 and T2.
The mismatch attenuation between RL and RL2 can be expressed as shown below.

That is, as described above, in FIG. 2, the impedance Zin seen from the terminals T, -T,' to the transformer side
'Well, Zin! y. Ten (becomes a Kira vine potato that reaches the owner of the restaurant).

The mismatch attenuation RL with respect to the internal resistance R of the signal source 6 of this impedance is 82 = Hakama, 6 = 4 Imo 3', then = 2 increase l≦; 3rd day 1st 82/8. If = y, then: Addition 1 ≦ ... ≦ Kure Ashi Hair ... Ramie King Te King Collection ... Hiroshi King Te King; Seki 1 = Add 1 ≦ San Migure Ashi Kago San Te Wang 3 ≧ King ≦ Mi Kure Ashito ≧ Kago Miimo Wang; ≧Ko 1 = Kasou l ≦Tsuruko; Mibu ≧ Kyo fake ≦ Ote) 1 = Kasai 12 Stage name (Azusa ￥
1 (Ship)”
-[It will be 21.

Similarly, the impedance when looking from the terminal L-T2' to the transformer side is Mukuzan = So2'0 (ki; Imo Tsuri ≧ 亨 茨子 Tsuri;;; and the matching attenuation RL2 at this time is RL2:2 addition. .

g1 Mitsubishi sheep, = 2ol.

g1 (receiving; beauty ≧ speech person Shintoshu ragiimo vine reed pole ten (¥30 thatched raised hands sheep utsuri reed hand), = 2 ol increase l ≦ g Kurashige ≧ Ugyu 8 dance ≦ hair growth; plexi 1 = 2010 g1 Takusan Mitsumi 3≦6 piles of hot potatoes≧
Kagoimo Tokure 1 = 2 mogl ≦; Otegure Dosho Hakusha ≧ Wang ≦; Sanjinsha Go Tomb King ≦ San Wang Bag ≧ Tomb 1 = 2. ．． Increase, 2 potatoes, Hayabusa, etc. Toxic ≧ Issued by Hyougejijikugeisha}l (ship).・Becomes the legs. ■The conditions for RL and RL2 to reach their maximum values are 6. = (1-P, XI + noon, y) 8, (10 y) For RZ, 62 = q + 8, XI-3, y) 8, (10 y).

Therefore, y=1 or 8. ≠B2, RL and RL simultaneously take the maximum value at the same 6, but do not take the maximum value at the same time at 8 and ≠82. So 8,=82 and RL,=R
To find the conditions for L, l20 versatility...; Poison ≧ Sanhojite, Shiku Poison Epiphytic Poison ≧ Three Spears)} l =, 2 Ichi Bird Azusa King; ≠ Kotobuki)}1=
--- Find the conditions under which [4' holds.

8,≠82 That is, since y≠1, RL=RL2 is satisfied from equation '4-6.

Then, 8C = Tsukazuito becomes.

From the above, both terminals 9 and 1 of the electrostatic shield 4 in FIG.
0, both terminals T2 and T2' of the secondary winding 3
The amount of mismatching increase or decrease RL between them becomes the maximum value.

In addition, in a transformer that almost satisfies y,=y2(n./mountain)2, R3=ki is also---y. } (character) 2
-y3, the mismatch attenuation amounts RL, RL2 between the terminals T, , T,' and between the terminals T2, T2' simultaneously reach their maximum values.

Furthermore, in the case of B,≠82, that is, y≠1, if the terminals 9 and 10 on both sides of the electrostatic shield are connected, the primary winding 2
The mismatch attenuation RL between the terminals T, , T, and ' on both sides becomes the maximum value, and R3={Rtei-y and 2(n./-
)21(1'n・A-y3y・10y2(n,/n2)2
If you connect , the mismatch attenuation RL between both terminals T, , T, ' of primary winding 2 and between terminals L, Q' of secondary winding 3 will be
,,RL2 take equal values.

However, it is clear that RL and RL do not reach their maximum values. FIG. 3 shows an example of numerical calculation using parameters B, , y, and 6 of the glue formula.

In this figure, curve A shows RL (〒RL2) when 8,=0.1, y=1.0, and curve B shows 8,=0.1,
Curve C shows RL when y=1.3 and curve C shows RL under the same conditions as curve 8. As is clear from this figure, curve A is 6
. The curve B has a pole at 6, and the curve C has a pole at 62.
In addition, curves B and C are 6. It can be seen that RL=RL.
It can be seen that 6 should be set so that the mismatch attenuation value in the case of the conventional transformer circuit shown in FIG. 1 is higher than this value. That is, from '11,■ and formula [3}, we get 26, (
10y) + (1/6) {(118,XI+B,y)}
2...■81
(10y)-(1/6) {(1-8,xl+8,y)}
>10 Meat Medium Hit or 2 Urasha Yora ≧ Toru #Miku Qi) Mamochi Yakusuji Poison Grass Morale)}〉・18. (≧+y) ---
It is sufficient to design 6 that satisfies [61].

6 from the '5' formula is 6,', 6 from the (6} formula is 82'
If taken, 8, ≧0. Since y≧0,6,,62>0, 6. ′> (10 Go 3 (Yep sheep {bu;; Kosan voice person Sanseiki y)} --- [7) 62'>
.

13,) {(118,y)-B,2y(10y)}
...■8,(
10y) {218, (10y)}.

6. Compare the magnitude relationship between ' and 62'.

That is, from the nine-legged formula, △ = (118, y) {(10B,) - B, 2 (10y)
}One (1181) {(10Ply) - B12y (10y
．． ...[9] Check whether is larger or smaller than zero.

Solving equation '91 gives △=8,2(y11)(y-1), so 6 for y>1, 6 for y=1,
'=62', y<1, and 6,'<62'.

Therefore, by setting the larger of these 8,', and 62', the mismatch attenuation RL, RL2 is greater than the transformer circuit shown in Figure 1.
It turns out that is obtained. For example, in the case of 8,=0.1 and y=1.3, which correspond to curves B and C in FIG. 3, since y>1, a condition corresponding to 6,' may be set. On the other hand, when we examine how much the operational attenuation characteristics deteriorate by adding the resistor 11, we find that the power supplied to the load resistor 7 in the circuit of FIG. Load resistance 7 assuming that transformer 8 is an ideal transformer
If the power supplied to is Pmax, the peak of the operating attenuation is peak =. Defined as: o・0g-PKinkusan1 (dB).

Based on this definition, when calculating the motion attenuation N in Figure 2, the mountain =
2010g [10 seasons {81 (10 y) + /6 (18
, ) (118, y)] (ship) ...{becomes 10. Comparison/
8 = base, y = 82/8, = harm, 6 = (R3' + y3'
)R,.

When the amount of operational attenuation is numerically calculated for an example using B, y and 6 in the equation as parameters, the result is as shown in FIG. In this figure, curve D is B,=0.1,y=1. , curve E is 8
,=0.1, t=1.3. As is clear from this figure, since the AI of 6→mark is the value of the operating attenuation when no additional winding is added, it can be seen that according to the present invention, the operating attenuation increases slightly. However, by slightly increasing the operational attenuation amount N, the mismatch attenuation amount RL can be significantly improved. For example, curves B and C in Figure 3
As is clear from and E, it is possible to improve RL, , RL by about 33B for increasing AI by about 1 dB. As described above, according to the present invention, by effectively utilizing the electrostatic shield between the primary winding and the secondary winding, the amount of mismatch attenuation can be increased even if the amount of operational attenuation is slightly sacrificed. You can get an improved transformer circuit inside.

Note that the present invention is not limited to the above-mentioned embodiments, and can be applied to a transformer in which one terminal of the primary winding 2 and the secondary winding 3 is not grounded, or a transformer in which only one terminal of one of the windings is grounded. It can be similarly realized for a transformer that is

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional transformer, FIG. 2a is a circuit diagram showing an embodiment of the present invention, and FIG. 2b is an equivalent circuit diagram thereof. FIG. 3 is a characteristic diagram showing the improvement effect of the present invention, and FIGS. 4a and 4b are circuit diagrams showing the equivalent circuit of FIG. 1. In Fig. 2, 1...magnetic core, 2...primary winding, 3...
...Secondary winding, 4...Electrostatic shield. No. 'Figure many? Illustration Leopard 2 Illustration Leopard Etsu Illustration Younger Brother 4 Ruiji

Claims (1)

[Claims] 1. In a transformer circuit having an electrostatic shield configured by winding a conductive foil whose width is approximately equal to the winding width only once between the primary winding and the secondary winding, The turn ratio of the secondary winding to the number of turns is N_1, and the internal resistance of the power supply on the primary winding side is R.
_1, when the load resistance on the secondary winding side is R_2, N
_1^2=(R_2)/(R_1) is substantially satisfied, and the DC resistance value of the primary winding is γ_1, the DC resistance value of the secondary winding is γ_2, the DC resistance of the conductive foil is γ_3,
When the reciprocal of the number of turns of the primary winding is N_2, ▲ Formula,
There are chemical formulas, tables, etc. ▼ or ▲ There are mathematical formulas, chemical formulas, tables, etc. A transformer circuit characterized in that one of the ends of the winding is grounded.