CN2784938Y - Broad rim coupler for detecting mobile phone circuit power - Google Patents

Abstract

The utility model discloses a broad rim coupler for detecting mobile phone circuit power, which comprises an upper layer conductive body, a lower layer conductive body, a power detecting chip, a medium layer and the output end of a power amplifier, wherein the upper layer conductive body and the lower layer conductive body are separated by the medium layer. The upper layer conductive body comprises a coupling end and an antenna end, the lower layer conductive body is provided with the power detecting chip and the coupling end of the upper layer conductive body is longitudinally coincided with the power detecting chip. The output end of a power amplifier is connected with the upper layer conductive body or the lower layer conductive body. The utility model uses the characteristic that the medium height between two metal layers of a mobile phone PCB board is low to obtain coupling purpose between the two layers of conductive bodies. Thus, power detection is realized.

Description

A kind of broadside coupled device that is used for the mobile phone circuit power detection

Technical field

The utility model relates to a kind of broadside coupled device, especially a kind of broadside coupled device that is used for the mobile phone circuit power detection.

Background technology

Nowadays, a large amount of of mobile phone popularize, and make the renewal of technology also develop rapidly, especially its circuit structure relevant with mobile phone.Being used for the means of detection power in the existing mobile phone has following several usually:

A kind of is directly to tell thinner relatively one from the main line of power amplifier output, sends into detection chip.The watt level that is coupled out like this is wayward, and promptly the degree of coupling is inaccurate, can not guarantee the consistance in the frequency band in addition, as shown in Figure 1.

Other has a kind of traditional coupling mechanism realizing method, promptly utilizes the characteristic of microstrip line narrow limit coupling, with two parallel microstrip lines power is coupled out, and sends into detection chip.The shortcoming of this way is that to take the PCB space bigger, be subjected to external interference easily, and isolation is bad.As shown in Figure 2.

In addition, two kinds of coupling mechanism implementations shown in Figure 3 can divide a class into, all are to realize in the printed board of high-k.The left side is interdigital line coupling mechanism; Branch line coupler cries on the right.They implement just complicated more, and are also higher to the requirement of printed board.Be difficult for realizing in the circuit board of mobile phone under miniaturization requires day by day.

Summary of the invention

Technical problem to be solved in the utility model provides a kind of broadside coupled device that is used for the mobile phone circuit power detection, make it can reduce the area occupied of pcb board, it is compact that structure becomes, reduce the influence of external interference simultaneously, realize more smooth connecting curve in the frequency band, reach wide band characteristic, can also realize strong coupling.

For solving the problems of the technologies described above, a kind of technical scheme that is used for the broadside coupled device of mobile phone circuit power detection of the utility model is, comprise upper strata electric conductor, lower floor's electric conductor, power detection chip, dielectric layer and power amplifier output terminal, described upper strata electric conductor and lower floor's electric conductor are separated by dielectric layer; The upper strata electric conductor comprises coupled end and antenna end, and lower floor's electric conductor is provided with the power detection chip; The coupled end of described upper strata electric conductor vertically overlaps with the power detection chip.Described power amplifier output terminal or be connected with the upper strata electric conductor perhaps is connected with the lower floor electric conductor.

The utility model utilizes parallel strap live width limit coupled characteristic, and the medium height features of smaller by means of between mobile phone pcb board (printed circuit board (PCB)) two metal levels is coupled between two-layer electric conductor, thereby realizes power detection.The utility model can reduce the area occupied of pcb board, makes its structure become compact, and such coupling scheme can reduce extraneous interference simultaneously, realize more smooth connecting curve in the frequency band, reach wide band characteristic, can also realize strong coupling.

Description of drawings

Below in conjunction with drawings and Examples the present invention is further described:

Fig. 1 carries out the synoptic diagram that circuit power detects for direct coupling system;

Fig. 2 utilizes the characteristic of microstrip line narrow limit coupling to carry out the synoptic diagram that circuit power detects;

Fig. 3 is for carrying out the synoptic diagram that circuit power detects with interdigital line coupling mechanism and branch line coupler;

Fig. 4 is a kind of structural representation that is used for the broadside coupled device of mobile phone circuit power detection of the utility model;

Fig. 5 is a kind of principle schematic that is used for the broadside coupled device of mobile phone circuit power detection of the utility model;

Fig. 6 is the reflection coefficient curve of the utility model embodiment;

Fig. 7, Fig. 8 are the transmission coefficient curve of the utility model embodiment.

Embodiment

Directional coupler is a kind of four port devices with directional transmissions characteristic.Directly directional coupler claimed structure compactness, the cabling of realizing on pcb board is simple.Just can adopt broadside coupled version in the occasion that needs strong coupling.Be divided into parallel broadside coupled and vertical broadside coupled two kinds of patterns again according to center conduction band placement location (with respect to ground plane).The utility model belongs to parallel broadside coupled.

As shown in Figure 4, a kind of broadside coupled device that is used for the mobile phone circuit power detection of the utility model, comprise upper strata electric conductor, lower floor's electric conductor, power detection chip, dielectric layer and power amplifier output terminal, described upper strata electric conductor and lower floor's electric conductor are separated by dielectric layer; The upper strata electric conductor comprises coupled end and antenna end, and lower floor's electric conductor is provided with the power detection chip; The coupled end of described upper strata electric conductor vertically overlaps with the power detection chip; Described power amplifier output terminal can be connected with the upper strata electric conductor, also can be connected with lower floor's electric conductor; The width of described upper strata electric conductor coupled end is less than the width of antenna end, and the length of described upper strata electric conductor coupled end is less than the length of antenna end.

As Fig. 5, described upper strata electric conductor and lower floor electric conductor lay respectively in the printed circuit board (PCB) on the two different metal levels, and described two different metal levels are all between two different ground planes.Because the medium aspect ratio between the pcb board double layer of metal is less, promptly the S among Fig. 5 is smaller.

At first, determine the degree of coupling C of the coupling mechanism of needs, this is next fixed according to the needs of system.Can be by formula C=20lg K (dB) in the hope of coupling coefficient K.

Then, the characteristic impedance Z 0 of given extension line (normally 50 ohm) is by formula

$Z_{0o}=Z_0\sqrt{\frac{1-K}{1+K}}$

$Z_{0e}=Z_0\sqrt{\frac{1+K}{1-K}}$

Can calculate unusual, ever mode characteristic impedance Z0o and Z0e.

According to the parity mode parametric method, utilize the angle preserving map principle to derive zero thickness (t=0) tape, among Fig. 5, parallel wide when W/S＞0.35 (wherein W is a live width, and S is the distance of two metal interlevels)

$Z_{0e}=\frac{188.3}{\sqrt{{\mathrm{\ϵ}}_r}}\frac{K\left(k^{\′}\right)}{K\left(k\right)}\left(\mathrm{\Ω}\right)---\left(1\right)$

$Z_{0o}=\frac{296.1}{\sqrt{{\mathrm{\ϵ}}_r}\frac{b}{s}\mathrm{arcthk}}\left(\mathrm{\Ω}\right)---\left(2\right)$

Limit coupling strip line characteristic impedance computing formula is

In the formula, the complete elliptic function integration of K (k), K (k ') the expression first kind, k, k ' they are moduluses; ε r is the specific inductive capacity of medium, b be two with reference to the distance between the ground, both B among Fig. 5.

When k was very little, we can utilize approximate formula:

$\frac{K\left(k^{\′}\right)}{K\left(k\right)}=\frac{2}{\mathrm{\π}}\ln \frac{4}{k}---\left(3\right)$

Size than the computing formula of W/b is:

By above-mentioned formula, the specific design step can be summarized as follows:

(1) solves the value of K (k ')/K (k) by formula (1) according to the value of given Z0e, ε r;

(2) calculate modulus k by formula (3);

(3), solve s/b by formula (2) according to given Z0o;

(4) calculate W/b by formula (4) at last;

B determines that by pcb board itself live width W just can calculate so usually.

Like this, broadside coupled directional coupler just can have been realized in the circuit board of mobile phone.It can be applied in the circuit of power detection part, occupies less pcb board area.

The coupling mechanism of this broadside coupled form can have comparatively flat frequency response in the frequency bandwidth of broad and the band.With the dielectric thickness is 1.27mm, and specific inductive capacity is that 4 pcb board is an example.The input end live width is 1.15mm, and the output terminal live width is 2.1mm, below the long 14mm of one deck electric conductor, above the long 12mm of one deck electric conductor, coupling regime length is 6.5mm.

By emulation and experimental test, obtain its family curve.The curve S 1,1 that obtains like this, as shown in Figure 6.As can be seen from the figure, frequency is all mated relatively goodly from 3GHz to 5GHz ,-below the 15dB.

Fig. 7, Fig. 8 are its transmission coefficient curve S 2,1.Analyze from figure, in the bandwidth of 3GHz～5GHz, the fluctuating of transmission parameter has good flatness less than 0.1dB.

Claims (6)

1. a broadside coupled device that is used for the mobile phone circuit power detection is characterized in that, comprises upper strata electric conductor, lower floor's electric conductor, power detection chip, dielectric layer and power amplifier output terminal, and described upper strata electric conductor and lower floor's electric conductor are separated by dielectric layer; The upper strata electric conductor comprises coupled end and antenna end, and lower floor's electric conductor is provided with the power detection chip; The coupled end of described upper strata electric conductor vertically overlaps with the power detection chip.

2. a kind of broadside coupled device that is used for the mobile phone circuit power detection according to claim 1, it is characterized in that, described upper strata electric conductor and lower floor electric conductor lay respectively in the printed circuit board (PCB) on the two different metal levels, and described two different metal levels are all between two different ground planes.

3. a kind of broadside coupled device that is used for the mobile phone circuit power detection according to claim 1 is characterized in that described power amplifier output terminal is connected with the upper strata electric conductor.

4. a kind of broadside coupled device that is used for the mobile phone circuit power detection according to claim 1 is characterized in that, described power amplifier output terminal is connected with the lower floor electric conductor.

5. a kind of broadside coupled device that is used for the mobile phone circuit power detection according to claim 1 is characterized in that the width of described upper strata electric conductor coupled end is less than the width of antenna end.

6. a kind of broadside coupled device that is used for the mobile phone circuit power detection according to claim 1 is characterized in that the length of described upper strata electric conductor coupled end is less than the length of antenna end.

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