CN202135098U

CN202135098U - Planar Balun

Info

Publication number: CN202135098U
Application number: CN201020689207U
Authority: CN
Inventors: 刘勇
Original assignee: Philips China Investment Co Ltd
Current assignee: Philips China Investment Co Ltd
Priority date: 2010-12-24
Filing date: 2010-12-24
Publication date: 2012-02-01
Anticipated expiration: 2020-12-24

Abstract

The utility model relates to a planar Balun (balanced-to-unbalanced transformer), in particular to a planar Balun which is suitable for the working environment with high-intensity magnetic field and improves the insertion loss/return loss performance. The planar Balun comprises two coils which are formed respectively on a top layer and a bottom layer of a PCB substrate. The coil on the top layer has two lead-out wires, which are symmetrically arranged relative to the coil body and are separated by a slit to serve as balanced terminals of the Balun. The two coils are resonated at an operating frequency. The coil on the top layer is large enough to cover the coil on the bottom layer. The planar Balun is characterized in that the body of the coil on the top layer only has the slit extending portion between the two lead-out wires. A hole of the coil on the top layer is replaced by the slit, thereby realizing acceptable insertion loss/return loss efficiency.

Description

A kind of plane Ba Lun

Technical field

The utility model relates to a kind of plane Ba Lun (balanced-unbalanced transformer), and relates in particular to a kind of plane Ba Lun that is applicable to the high-intensity magnetic field operational environment and inserts loss/return loss performance improvement.

Background technology

Ba Lun is the necessary parts of amplifier, and when two transistors were worked with the symmetrical operation pattern, it was used for driving this a pair of transistor with the mode of balance.In output stage, also can use Ba Lun transistorized balance output to be converted to non-equilibrium (single-ended) output of amplifier with opposite direction.

Routinely, in low frequency and radio-frequency push-pull amplifier, often adopt the Ba Lun design of centre tapped transformer and line transformer as routine.In addition, iron core can help line transformer to improve its low frequency performance and expand its bandwidth.Yet iron core is with incompatible such as near magnetic resonance hole (MR bore) operational environment of high-intensity magnetic field that waits.

In the prior art design of being done by NXP semiconductor (NXP Semiconductors), gaseous core transmission line Ba Lun is suitable for being operated near the magnetic resonance hole.And this plane Ba Lun makes through the technology identical with PCB, and therefore full automatic manufacturing process can make the consistency of plane Ba Lun maximized and get rid of as far as possible because the manual quality of being brought of making of people is uncertain.

Yet; For the above-mentioned plane Ba Lun design of NXP; Only pass through up-sizing; It also can not be applicable to the operating frequency that some is specific, for example in the middle of the application of 1.5T MR (64MHz), because because the hole that coil had on the top layer makes it on insertion loss, return loss, can have relatively poor efficient.

The utility model content

In view of the above problems, the invention of the utility model has been made the utility model through overtesting.Particularly, the utility model has overcome this problem through the hole that substitutes the coil on the top layer with long slit.

The utility model provides a kind of plane Ba Lun to realize above-mentioned thought.

According to the embodiment of the utility model, a kind of plane Ba Lun is provided, said plane Ba Lun comprises the top layer that is respectively formed at the PCB substrate and two coils on the bottom, wherein

Coil on the said top layer have that main body with respect to this coil is symmetrical set and two lead-out wires separating by slit with balance end as this Ba Lun; The coil of said two coils on operating frequency resonance and said top layer is enough big so that cover the coil on the said bottom

Said plane Ba Lun is characterised in that:

The main body of the coil on the said top layer only has the extension of said slit between said two lead-out wires.

Through this design, can improve plane Ba Lun non-equilibrium end place return loss and make it go for the application of 1.5T MR (64MHz).

In an embodiment of the utility model, the coil on the said top layer is a single-turn circular coil, and the coil on the said bottom is that the length of arrangement wire of the coil on quarter-wave short-circuit line and the said bottom is 1/4th of a guide wavelength.

Said plane Ba Lun also comprises tuning capacitor, and on the extension of said slit or said slit, said tuning capacitor is installed.

And in another embodiment of the utility model; Coil on the said top layer is a single-turn circular coil; And the coil on the said bottom can not adopt the design of quarter-wave short-circuit line, but but can identically with the coil on the said top layer be provided with in the opposite directionly.In this case, similar with the coil on the top layer, the coil on the bottom also needs a tuning capacitor so that produce resonance.

With reference to the explanation that combines accompanying drawing to carry out, other purposes of the utility model and effect will become more obviously and easy to understand more.

Description of drawings

To combine embodiment below and more specifically introduce and explain the utility model with reference to accompanying drawing, in the accompanying drawings:

Fig. 1 is the sketch map according to the plane Ba Lun of prior art;

Fig. 2 is the 3D view according to the plane Ba Lun of an embodiment of the utility model;

Fig. 3 shows the concrete size according to the plane Ba Lun of an embodiment of the utility model;

Fig. 4 shows according to the simulation of the return loss of the non-equilibrium port of Ba Lun, plane of the utility model and the comparison between the test result; And

Fig. 5 shows the sketch map according to the plane Ba Lun of another embodiment of the utility model.

Identical in the accompanying drawings Reference numeral is represented similar or corresponding characteristic and/or function.

Embodiment

The embodiment of utility model hereinafter will more specifically be described with reference to accompanying drawing.

Fig. 1 is the sketch map according to the plane Ba Lun of prior art.

With reference to Fig. 1, the plane Ba Lun that the NXP semiconductor is designed makes through the technology identical with PCB, its only be to 174MHz to the applied environment of 230MHz and as shown in the figure, the coil on the PCB top layer has a square hole.

Mention like the introductory song of the utility model application, because the design of this square hole, through only amplifying the size of the semi-conductive plane Ba Lun of NXP, it can not be applicable to the for example high-intensity magnetic field applied environment of 1.5TMR (64MHz).Reason be this design since on its top layer the square hole of coil can to cause inserting loss/return loss efficient good and can't satisfy service behaviour.

Fig. 2 is the 3D view according to the plane Ba Lun of an embodiment of the utility model.

As shown in Figure 2, this plane Ba Lun comprises the top layer that is respectively formed at the PCB substrate and two coils on the bottom.

Coil on the said top layer have that main body with respect to this coil is symmetrical set and two lead-out wires separating by slit with balance end as this Ba Lun; (for example, 64MHz) coil on resonance and the said top layer is enough big so that cover the coil on the said bottom in operating frequency for said two coils.

Can clearly be seen that from the contrast of Fig. 1 and Fig. 2 the plane Ba Lun of the utility model is characterised in that:

The main body of the coil on the top layer only has the extension of two slits between the lead-out wire.

In other words, the coil on the top layer among Fig. 2 does not have the hole shown in Fig. 1, but complete extension branch replacement by slit.

Through this design, through emulation and result of the test discovery can improve plane Ba Lun non-equilibrium end place return loss and make it go for the application of 1.5T MR.This will combine Fig. 4 further to set forth below.

As is known to the person skilled in the art and as shown in Figure 2, the coil on the top layer of plane Ba Lun further is included in a lead-out wire on the opposite side of said two lead-out wires, and this lead-out wire is as the non-equilibrium end of Ba Lun.

In the embodiment shown in Figure 2; Because the coil on the bottom adopts the mode of quarter-wave short-circuit line; Therefore the resonance of the coil on this bottom can be realized through himself, and the length of arrangement wire of the coil on the said bottom is 1/4th of a guide wavelength.The resonance of the coil on the top layer then need rely on a tuning capacitor to realize.In this embodiment, on the extension of said slit, said tuning capacitor is installed.But it will be understood by those skilled in the art that said tuning capacitor also can be connected across on the said slit.

In one embodiment, the coil on the said top layer is a single-turn circular coil, and the coil on the said bottom can also can be multiturn for single turn, and promptly the number of turn N of coil can be more than or equal to 1 on the bottom.

Above-mentioned two coils can be formed by the metal line on the PCB substrate.As the material of the metal line on the PCB substrate,, can preferably adopt copper as known in those skilled in the art.

Further should be noted that; Although the utility model only adopts the instance of square coil as coil shape in the accompanying drawings; But those skilled in the art should expect; According to the specific requirement of using, the shape of these two coils also can be circular or any suitable distortion.

In addition; In order to make the coil on the said top layer enough big so that cover the coil on the said bottom; The width of said slit should be less than d; And the terminal point of the extension of said slit is within the length range of the positive and negative d in center of main body of the coil of distance on the said top layer, wherein d be on the said bottom coil in the length of side or the diameter in the formed hole of a circle.

Find that on the basis of the utility model inventor test of many times slit width is preferably in the scope from 0.5mm to 2mm, so that its performance can be accepted for the plane Ba Lun that is used for 1.5T MR RF amplifier.

Fig. 3 shows the concrete size according to the plane Ba Lun of an embodiment of the utility model.

In this embodiment, to adopt the design of four circles and this two coils all be square to the coil on the bottom.

In addition, as shown in Figure 3, the length of side of the square main body of the coil on the top layer is 45mm, is 1mm and the outer length of side of outermost one circle of the coil on the said bottom is the width of 44mm and slit.As shown in the figure, in the Ba Lun of this plane, have tuning capacitor C1 as its unique circuit block, and in this embodiment, selecting capacitance is that capacitor about 1.1nF is as tuning capacitor C1.

Fig. 4 shows according to the simulation of the return loss of the non-equilibrium port of Ba Lun, plane of the utility model and the comparison between the test result.

Can find out that on scheming for for the plane Ba Lun that embodiment designed of the utility model, its centre frequency is roughly 64MHz, and its bandwidth of operation frequency range of 10dB place (be defined as return loss to drop to-) is about 8MHz.Therefore its relative bandwidth is 8MHz/64MHz=12.5%.Therefore, can find out that from simulation and test result the plane Ba Lun of the utility model goes for the applied environment of 1.5T MR.

Can find out that from curve shown in Figure 4 analog result and test result are mated finely, wherein only have small deviation between these curves.And the reason that produces deviation is because the nominal capacitance value inaccuracy causes, and particularly uses together under the situation with the capacitance that forms tuning capacitor C1 at two of 20% accuracy or three capacitors.

As shown in Figure 5, in this embodiment, the coil on the said top layer is a single-turn circular coil, and the coil on the said bottom can not adopt the design of quarter-wave short-circuit line, but but can identically with the coil on the said top layer be provided with in the opposite directionly.In this case, similar with the coil on the top layer, the coil on the bottom also needs a tuning capacitor so that produce resonance.

In this embodiment; Coil produces the mode difference of resonance on bottom; Because itself and the foregoing description have all adopted the slit extension to assign to replace the design in hole of the prior art, so it also can realize the improvement to performance in the high-intensity magnetic field applied environment.

It should be noted that the foregoing description signal and unrestricted the utility model and those skilled in the art should design various alternate embodiments under the situation that does not break away from the accompanying claims scope.In claims, should any Reference numeral in the bracket be understood as is the restriction to claim.Word " comprises " not getting rid of and has element or the step of not enumerating in claim or the specification.Word " " before the element or " one " do not get rid of and have a plurality of this elements.In having enumerated system's claim of plurality of units, can implement by same type of software and/or hardware for several kinds in these elements.Use word " first ", " second " and " the 3rd " etc. not to represent any ordinal relation.Should these Word Understandings be become title.

Claims

1. plane Ba Lun, said plane Ba Lun comprise the top layer that is respectively formed at the PCB substrate and two coils on the bottom, wherein

Said plane Ba Lun is characterised in that:

2. plane Ba Lun according to claim 1 is characterized in that the coil on the said top layer is a single-turn circular coil, and the number of turn N of the coil on the said bottom is at least 1.

3. plane Ba Lun according to claim 1; It is characterized in that said two coils are formed by the wiring of the copper on the PCB substrate; Coil on the said bottom is the quarter-wave short-circuit line, and the length of arrangement wire of the coil on the said bottom is 1/4th of a guide wavelength.

4. plane Ba Lun according to claim 3 is characterized in that N is four.

5. plane Ba Lun according to claim 4 is characterized in that said two coils are square.

6. plane Ba Lun according to claim 5, the length of side that it is characterized in that the square main body of the coil on the said top layer is 45mm, and the outer length of side of outermost one circle of the coil on the said bottom is 44mm.

7. plane Ba Lun according to claim 4 is characterized in that said two coils are circular.

8. according to any described plane Ba Lun among the claim 5-7; The width that it is characterized in that said slit is less than d; And the terminal point of the extension of said slit is within the length range of the positive and negative d in center of main body of the coil of distance on the said top layer, wherein d be on the said bottom coil in the length of side or the diameter in the formed hole of a circle.

9. plane Ba Lun according to claim 8, the scope of width that it is characterized in that said slit is from 0.5mm to 2mm.

10. plane Ba Lun according to claim 9, the width that it is characterized in that said slit is 1mm.

11. plane Ba Lun according to claim 8 is characterized in that the terminal point of the extension of said slit is in the center of the main body of the coil on the said top layer.

12. plane Ba Lun according to claim 1 it is characterized in that the coil on the said top layer is a single-turn circular coil, but the coil on the said bottom is identical in the opposite direction with the coil on the said top layer.

13. plane Ba Lun according to claim 1 is characterized in that said plane Ba Lun also comprises tuning capacitor, and on the extension of said slit or said slit, said tuning capacitor is installed.