EP1198861B1 - Balanced to unbalanced circuit - Google Patents
Balanced to unbalanced circuit Download PDFInfo
- Publication number
- EP1198861B1 EP1198861B1 EP00946644A EP00946644A EP1198861B1 EP 1198861 B1 EP1198861 B1 EP 1198861B1 EP 00946644 A EP00946644 A EP 00946644A EP 00946644 A EP00946644 A EP 00946644A EP 1198861 B1 EP1198861 B1 EP 1198861B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- circuit
- sub
- conductor
- balun
- balanced
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P5/00—Coupling devices of the waveguide type
- H01P5/08—Coupling devices of the waveguide type for linking dissimilar lines or devices
- H01P5/10—Coupling devices of the waveguide type for linking dissimilar lines or devices for coupling balanced with unbalanced lines or devices
Description
- The present invention relates to a balanced to unbalanced circuit (BALUN) according to the preamble of
Claim 1. - High frequency electric signals can be transmitted in two often occurring ways, namely either balanced or unbalanced. In the case of balanced transmission there is used two conductors in which electric currents are constantly in antiphase. Unbalanced transmission, on the other hand, uses only one signal conductor and the signal (the current) is returned via earth. The balanced transmission is differential in nature and therewith less sensitive to disturbances and interference than the unbalanced transmission.
- Balanced and unbalanced transmissions are often mixed in radio systems. It is therefore necessary to be able to convert a balanced signal to an unbalanced signal and vice versa with the smallest possible losses. Balun circuits are used to this end.
- The properties of the balun circuit depend on impedance difference and phase difference for odd and even modes in the high frequency electric signal.
- A typical balun is the Marchand-balun which includes four λ/4 waveguides connected in pairs. In many cases, a balanced port shall be connected to an input or to an output of a differential amplifier. Normally, it is necessary to DC-bias the amplifiers and consequently a DC-wise short circuit of the balanced port to earth cannot be accepted.
This has earlier been solved by including two capacitors between the actual balanced circuit and the balanced load. The capacitors are discrete capacitors which are chosen so that their resonance frequency coincides with the signal frequency. - The capacitance is then balanced by the own parasite inductance of the capacitor and ideally behaves transparent at the frequency concerned.
- A problem with discrete capacitors is that they are relatively bulky and cannot be implemented readily when integrated in multilayer printed circuit boards or ceramic substrates.
- When biasing the differential amplifiers it is normally necessary to connect present day balun circuits to a current source or voltage source via additional discrete components. This applies particularly to the Marchand balun and also constitutes a problem.
- An object of the present invention is to at least reduce the aforesaid problem.
- This object is achieved in accordance with a first aspect of the invention by means of a device according to
Claim 1. - One advantage afforded by the present invention is that performance is improved with regard to loss reductions and better phase characteristics of the balanced signal.
- Another advantage is that it can be simulated more readily than in the case of existing solutions, since it is not necessary to rely on discrete component models.
- The invention will now be described in more detail with reference to preferred embodiments thereof and also with reference to the accompanying drawings.
-
- Figure 1 is a principle diagram of a classic Marchand-balun.
- Figure 2 is a principle diagram of one embodiment of a Marchand-balun constructed in accordance with the present standpoint of techniques so as to avoid DC-wise short circuiting to earth of the balanced output signal.
- Figure 3 is a principle diagram of one embodiment of an inventive Marchand-balun.
- In order to provide a better understanding of the particular features of the inventive device, reference is made first to Figures 1 and 2.
- Figure 1 illustrates an embodiment of a classic Marchand-
balun 1, which includes a first and asecond sub-circuit first sub-circuit 10 includes anupper conductor 10U, alower conductor 10L and a discrete layer disposed between said conductors. Theupper conductor 10U and thelower conductor 10L in thefirst sub-circuit 10 are connected together capacitively and inductively, with a given coupling constant. Thefirst sub-circuit 10 corresponds to, or essentially to, a first λ/4-wave guide. Similarly, thesecond sub-circuit 20 includes anupper conductor 20U and alower conductor 20L and a dielectric layer disposed between said conductors. Theupper conductor 20U and thelower conductor 20L are connected to one another in saidsecond sub-circuit 20 capacitively and inductively, with a given coupling constant. The second sub-circuit corresponds to, or essentially to, a second λ/4-wave guide. - An input P1 is connected to a first side on the
upper conductor 10U in thefirst sub-circuit 10. A second side on theupper conductor 10U in thefirst sub-circuit 10 is connected to a first side on theupper conductor 20U in thesecond sub-circuit 20 via aconnecting conductor 15. A second side on theupper conductor 20U in thesecond sub-circuit 20 is open. A first side on thelower conductor 10L in thefirst sub-circuit 10 is connected to earth. A second side of thelower conductor 10L in thefirst sub-circuit 10 is connected to a first output port P2. A first side on thelower conductor 20L in thesecond sub-circuit 20 is connected to a second output port P3. A second side of thelower conductor 20L in thesecond sub-circuit 20 is connected to earth. - Figure 2 illustrates a Marchand-balun circuit 1A. The sole difference between the Marchand-balun circuit 1A and the classic Marchand-
balun 1 shown in Figure 1 is that the Figure 2 circuit includes twocapacitors first capacitor 50 is arranged between the output port P2 and the second side of thelower conductor 10L in thefirst sub-circuit 10. Asecond capacitor 60 is arranged between the output port P3 and the first side of thesecond conductor 20L in thesecond sub-circuit 20. - Figure 3 illustrates an embodiment of an inventive balun circuit 1B. The illustrated embodiment of the inventive balun circuit is shown in stripline form, in other words the mutually connected conductors lie in different planes. The inventive balun circuit 1B includes a first and a
second sub-circuit first sub-circuit 10 includes anupper conductor 10U, alower conductor 10L and a dielectric layer disposed between the said conductors. Theupper conductor 10U and thelower conductor 10L in thefirst sub-circuit 10 are connected together capacitively and inductively with a given coupling constant. Thefirst sub-circuit 10 corresponds to, or essentially to, a first λ/4-wave guide. Similarly, thesecond sub-circuit 20 includes anupper conductor 20U and alower conductor 20L and a dielectric layer disposed between said conductors. Theupper conductor 20U and thelower conductor 20L in thesecond sub-circuit 20 are connected together capacitively and inductively with a given coupling constant. The second sub-circuit corresponds to, or essentially to, a second λ/4-wave guide. - An input P1 is connected to a first side of the
upper conductor 10U in thefirst sub-circuit 10. A second side on theupper conductor 10U in thefirst sub-circuit 10 is connected to a first side on theupper conductor 20U in thesecond sub-circuit 20 via aconnecting conductor 15. A second side on theupper conductor 20U in thesecond sub-circuit 20 is open. A first side on thesecond conductor 10L in thefirst sub-circuit 10 is connected to a first side of a first open terminating λ/4-wave guide 30. A second side on thelower conductor 10L in thefirst sub-circuit 10 is connected to a first output port P2. A first side on thelower conductor 20L in thesecond sub-circuit 20 is connected to a second output port P3. A second side on thelower conductor 20L in thesecond sub-circuit 20 is connected to a first side on a second open, terminating λ/4-wave guide 40. - The dielectric material disposed between the
upper conductors lower conductors - A
point 70 between the third λ/4-wave guide 30 and thelower conductor 10L in the first sub-circuit 10 functions as an RF-wise earth point. Apoint 80 between the fourth λ/4-wave guide 40 and thelower conductor 20L in the second sub-circuit 20 functions as an RF-wise earth point. - The λ/4-wave guides in the illustrated embodiment of the balun circuit 1B may be made of metal, for instance from a silver alloy, copper, tungsten or aluminium. The dielectric material may comprise a ceramic material, polymeric material, an electrically non-conductive organic material, silicon dioxide or silicon nitride.
- Although the inventive balun circuit will function for all wave lengths, the length of each λ/4-wave guide must be manageable for purely practical reasons.
- The balun circuit 1B may be of the microstrip or stripline kind.
Claims (3)
- A balun circuit (1B) comprising a first sub-circuit (10) and a second sub-circuit (20) each of which corresponds to, or essentially to, a λ/4-wave guide, wherein the first sub-circuit (10) includes a first conductor (10U), a second conductor (10L) and a dielectric layer disposed between said first and second conductors, wherein said conductors are connected together capacitively and inductively, wherein the second sub-circuit (20) includes a first conductor (20U), a second conductor (20L) and a dielectric layer disposed between said first and said second conductors, said conductors being connected together capacitively and inductively, wherein a first side on the first conductor (10U) in the first sub-circuit (10) is connected to an input port (P1), a second side on the first conductor (10U) in the first sub-circuit (10) is connected to a first side on the first conductor (20U) in the second sub-circuit (20) via a connecting conductor (15), a second side on the second conductor (10L) in the first sub-circuit (10) is connected to a first output port (P2) and a first side on the second conductor (20L) in the second sub-circuit (20) is connected to a second output port (P3), characterized in that a first open, terminating λ/4-wave guide (30) is connected to a first side on the second conductor (10L) in the first sub-circuit (10), and in that a second, open terminating λ/4-wave guide (40) is connected to a second side of said second conductor (20L) in the second sub-circuit (20).
- A balun circuit according to Claim 1, characterized in that the balun circuit is of the stripline kind.
- A balun circuit according to Claim 1, characterized in that the balun circuit is of the microstrip kind.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
SE9902497 | 1999-06-30 | ||
SE9902497A SE513345C2 (en) | 1999-06-30 | 1999-06-30 | balun |
PCT/SE2000/001350 WO2001001514A1 (en) | 1999-06-30 | 2000-06-26 | Balanced to unbalanced circuit |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1198861A1 EP1198861A1 (en) | 2002-04-24 |
EP1198861B1 true EP1198861B1 (en) | 2007-07-25 |
Family
ID=20416316
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP00946644A Expired - Lifetime EP1198861B1 (en) | 1999-06-30 | 2000-06-26 | Balanced to unbalanced circuit |
Country Status (11)
Country | Link |
---|---|
EP (1) | EP1198861B1 (en) |
JP (1) | JP2003503928A (en) |
KR (1) | KR20020013938A (en) |
CN (1) | CN1175516C (en) |
AU (1) | AU6036900A (en) |
CA (1) | CA2377963A1 (en) |
DE (1) | DE60035694D1 (en) |
HK (1) | HK1048197B (en) |
SE (1) | SE513345C2 (en) |
TW (1) | TW431079B (en) |
WO (1) | WO2001001514A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100531782B1 (en) * | 2002-08-13 | 2005-11-29 | 엘지전자 주식회사 | Manufacturing method of balun |
WO2018041809A1 (en) * | 2016-08-29 | 2018-03-08 | Arralis Holdings Limited | A multiband circularly polarised antenna |
CN109088137B (en) * | 2018-08-31 | 2022-03-01 | 易力声科技(深圳)有限公司 | Lumped circuit balance converter applied to double-sided parallel lines |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6263198B1 (en) * | 1996-06-14 | 2001-07-17 | Wj Communications, Inc. | Multi-layer printed wiring board having integrated broadside microwave coupled baluns |
US5697088A (en) * | 1996-08-05 | 1997-12-09 | Motorola, Inc. | Balun transformer |
JP3576754B2 (en) * | 1997-03-31 | 2004-10-13 | 日本電信電話株式会社 | Balun circuit and balanced frequency converter |
-
1999
- 1999-06-30 SE SE9902497A patent/SE513345C2/en not_active IP Right Cessation
- 1999-09-27 TW TW088116506A patent/TW431079B/en not_active IP Right Cessation
-
2000
- 2000-06-26 CA CA002377963A patent/CA2377963A1/en not_active Abandoned
- 2000-06-26 JP JP2001506637A patent/JP2003503928A/en not_active Withdrawn
- 2000-06-26 AU AU60369/00A patent/AU6036900A/en not_active Abandoned
- 2000-06-26 CN CNB008097887A patent/CN1175516C/en not_active Expired - Fee Related
- 2000-06-26 DE DE60035694T patent/DE60035694D1/en not_active Expired - Lifetime
- 2000-06-26 KR KR1020017016717A patent/KR20020013938A/en not_active Application Discontinuation
- 2000-06-26 WO PCT/SE2000/001350 patent/WO2001001514A1/en active Search and Examination
- 2000-06-26 EP EP00946644A patent/EP1198861B1/en not_active Expired - Lifetime
-
2003
- 2003-01-13 HK HK03100298.6A patent/HK1048197B/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
SE9902497D0 (en) | 1999-06-30 |
CN1359550A (en) | 2002-07-17 |
CN1175516C (en) | 2004-11-10 |
TW431079B (en) | 2001-04-21 |
CA2377963A1 (en) | 2001-01-04 |
WO2001001514A1 (en) | 2001-01-04 |
SE9902497L (en) | 2000-08-28 |
HK1048197B (en) | 2005-06-24 |
SE513345C2 (en) | 2000-08-28 |
KR20020013938A (en) | 2002-02-21 |
HK1048197A1 (en) | 2003-03-21 |
JP2003503928A (en) | 2003-01-28 |
EP1198861A1 (en) | 2002-04-24 |
AU6036900A (en) | 2001-01-31 |
DE60035694D1 (en) | 2007-09-06 |
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