CN115133898A - LC balun circuit - Google Patents
LC balun circuit Download PDFInfo
- Publication number
- CN115133898A CN115133898A CN202210613254.5A CN202210613254A CN115133898A CN 115133898 A CN115133898 A CN 115133898A CN 202210613254 A CN202210613254 A CN 202210613254A CN 115133898 A CN115133898 A CN 115133898A
- Authority
- CN
- China
- Prior art keywords
- port
- pass filter
- capacitor
- inductance
- filter network
- 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.)
- Pending
Links
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/42—Balance/unbalance networks
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
- H03H7/38—Impedance-matching networks
Abstract
The invention discloses an LC balun circuit, which belongs to the technical field of broadband LC balun circuits and comprises high-pass filter networks 1 and 2, low-pass filter networks 1 and 2, ports 1, 2 and 3 and a reference ground, wherein the high-pass filter networks 1 and 2 have the same topological structure and are both T-shaped two-port networks formed by LC, and the low-pass filter networks 1 and 2 have the same topological structure and are both T-shaped two-port networks formed by LC; port 1 of high-pass filter network 1 HP1 And port 1 of low-pass filter network 1 LP1 Connected in parallel to port 1 of the invention, port 2 of high-pass filter network 2 HP2 Port 2 of low-pass filter network 2 connected to port 2 of the present invention LP2 And the port 3 of the invention, the high-pass filter networks 1 and 2 are connected in series, and the low-pass filter networks 1 and 2 are connected in series. The embodiment shows that the broadband LC balun circuit with the relative bandwidth of 67.6% can be realized by the broadband LC balun circuit.
Description
Technical Field
The invention relates to the technical field of broadband LC balun circuits, in particular to an LC balun circuit.
Background
Balun is a device for converting a balanced (differential) signal into an unbalanced (single-ended) signal or converting an unbalanced signal into a balanced signal, and is widely applied in modern communication systems, for example, Balun is required in design implementation of elements such as a balanced mixer, a push-pull amplifier, a differential low-noise amplifier, and an antenna feed network. Since the modern communication system is developed in a wide band and a small size, the design direction of Balun in the industry is also a wide band, a small size and a planar structure. The industry commonly uses a first-order Lattice LC Balun circuit, which is a Balun circuit structureSimple, but only at the central frequency point f 0 The best Balun characteristic is achieved, the working bandwidth is very narrow, and the Balun of the type cannot meet the working bandwidth requirement of modern broadband wireless communication.
Disclosure of Invention
The present invention aims to provide an LC balun circuit to solve the problems set forth in the background art.
In order to achieve the above object, the present invention provides the following technical solutions: an LC balun circuit comprises high- pass filter networks 1 and 2, low- pass filter networks 1 and 2, ports 1, 2 and 3 and a reference ground G, wherein the high- pass filter networks 1 and 2 and the low- pass filter networks 1 and 2 are both two-port networks, the ports 1, 2 and 3 are unbalanced ports which are externally connected, the ports are respectively composed of terminals 1 and 1 ', terminals 2 and 2' and terminals 3 and 3 ', the terminals 1', 2 'and 3' are electrically connected with the reference ground G, meanwhile, the terminals 2 and 3 form balanced ports which are electrically connected with an external balanced system, and the port 1 is electrically connected with the external unbalanced system;
the high-pass filter network 1 comprises a capacitor C 1 Inductor L 1 Capacitor C 21 Port 1 HP1 、2 HP1 And ground reference G, wherein port 1 HP1 From terminal 1 HP1 And 1' HP1 Formation of port 2 HP1 By terminal 2 HP1 And 2' HP1 Is constituted of terminal 1' HP1 And 2' HP1 Are all electrically connected with a reference ground G, a capacitor C 1 And C 21 Are sequentially connected in series with the terminal 1 HP1 And terminal 2 HP1 Between, inductance L 1 Electrically connected to the capacitor C 1 And C 21 Between the connection point of (C) and a reference ground G, a capacitance C 1 Inductor L 1 And a capacitor C 21 Form a T-network, and a capacitor C 1 And C 21 Are equal in capacitance value, i.e. C 1 ＝C 21 ；
The high-pass filter network 2 comprises a capacitor C 22 Inductor L 2 Capacitor C 3 Port 1 HP2 、2 HP2 And, with reference to G, has exactly the same extension as the described medium-high-pass filtering network 1 of Balun according to the inventionThe values of the inductance and the capacitance at the corresponding positions of the two high-pass filter networks are respectively equal, namely L 2 ＝L 1 ， C 22 ＝C 1 ，C 3 ＝C 21 ；
The low-pass filter network 1 comprises an inductor L 3 Capacitor C 4 An inductor L 41 Port 1 LP1 、2 LP1 And ground reference G, wherein port 1 LP1 From terminal 1 LP1 And 1' LP1 Is formed of a port 2 LP1 By terminal 2 LP1 And 2' LP1 Is constituted of terminal 1' LP1 And 2' LP1 Are all electrically connected with a reference ground G, an inductor L 3 And L 41 Are sequentially connected in series to the terminal 1 LP1 And terminal 2 LP1 Between, capacitance C 4 Electrical property connected to the inductor L 3 And L 41 Between the connection point of (3) and a reference ground G, an inductance L 3 Capacitor C 4 And an inductance L 41 Form a T-network and an inductance L 3 And L 41 Equal in inductance value, i.e. L 3 ＝L 41 ；
The low-pass filter network 2 comprises an inductor L 42 Capacitor C 5 Inductor L 5 Port 1 LP2 、2 LP2 And a reference ground G, the low-pass filter network 1 in Balun of the invention has the same topological structure, and the values of the inductance and the capacitance at the corresponding positions of the two low-pass filter networks are respectively equal, namely L 42 ＝L 3 ， L 5 ＝L 41 ，C 5 ＝C 4 。
Further, port 1 of the high-pass filter network 1 HP1 And port 1 of said low-pass filter network 1 LP1 Connected in parallel to port 1 of the present invention;
An LC balun circuit as claimed in claims 1 and 2 wherein the external load impedance Z comprises the balanced load impedance R of the balanced port B And the load impedance R of the unbalanced port UN Wherein R is B And R UN Resistance value R of B And R UN Are all real numbers;
balanced load impedance R of balanced port B Electrically connected to terminals 2 and 3;
unbalanced port load impedance R UN Electrical connections are made to terminals 1 and 1'.
Further, a capacitor C 21 And said capacitor C 22 In series relation, the capacitor C 21 And said capacitor C 22 Can be equivalent to a capacitor C 2 The capacitance value relationship is C 21 ＝C 22 ＝2C 2 ；
Further, the inductance L 41 And the inductance L 42 In series relation, the inductance L 41 And the inductance L 42 Can be equivalent to an inductor L 4 The relation of inductance is L 41 ＝L 42 ＝L 4 /2；
Further, the target central working frequency of balun design is f 0 Then ω is 0 ＝2×π×f 0 . The inductance and capacitance values must also satisfy the following relationship:
compared with the prior art, the invention has the beneficial effects that:
the LC balun circuit provided by the invention only uses lumped parameter inductance L and capacitance C, and does not need additional mutual inductance components, thereby simplifying the design complexity and realizing the broadband and miniaturization of elements. The Balun embodiment of the invention shows that the working frequency range is 2.673-5.401GHz, the relative bandwidth is 67.6%, the design target of the broadband working bandwidth is achieved, and the Balun function is realized, and meanwhile, the impedance matching between the source impedance and the load impedance is also realized, so that the wireless communication system applying the Balun function does not need additional impedance matching components, and the size of the system can be further reduced.
Drawings
FIG. 1 is a schematic diagram of Balun according to the present invention;
FIG. 2 is a diagram of a Balun topology of the present invention;
FIG. 3 is a schematic diagram of the Balun topology of the present invention;
FIG. 4 shows the load condition of Balun in practical operation, in which the unbalanced system connected to the external by the unbalanced port presents a load impedance R at the unbalanced port UN A balanced system with balanced ports connected to the outside presents a balanced (differential) load impedance at the balanced ports of R B ；
FIG. 5 shows the simulation results of the return loss (dBS (1,1)) of the unbalanced port in the first embodiment of the present invention within the operating band;
FIG. 6 is a simulation result of the output port balanced signal amplitude imbalance in the operating frequency band according to the first embodiment of the present invention;
fig. 7 is a simulation result of the output port balanced signal phase difference within the operating frequency band according to the first embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, an LC balun circuit includes high- pass filter networks 1 and 2, low- pass filter networks 1 and 2, ports 1, 2, 3, and a reference ground G, where the high- pass filter networks 1 and 2 and the low- pass filter networks 1 and 2 are both two-port networks, the ports 1, 2, and 3 are unbalanced ports that are externally connected according to the present invention, and respectively include terminals 1 and 1 ', terminals 2 and 2', and terminals 3 and 3 ', the terminals 1', 2 ', and 3' are electrically connected to the reference ground G, and at the same time, the terminals 2 and 3 also form balanced ports that are electrically connected to an external balanced system, and the port 1 is electrically connected to the external unbalanced system;
the high-pass filter network 1 comprises a capacitor C 1 An inductor L 1 Capacitor C 21 Port 1 HP1 、2 HP1 And ground reference G, wherein port 1 HP1 From terminal 1 HP1 And 1' HP1 Formation of port 2 HP1 By terminal 2 HP1 And 2' HP1 Is constituted of terminal 1' HP1 And 2' HP1 Are all electrically connected with a reference ground G, a capacitor C 1 And C 21 Are sequentially connected in series to the terminal 1 HP1 And terminal 2 HP1 Between, inductance L 1 Electrically connected to the capacitor C 1 And C 21 Between the connection point of (C) and a reference ground G, a capacitance C 1 Inductor L 1 And a capacitor C 21 Form a T-network, and a capacitor C 1 And C 21 Are equal in capacitance value, i.e. C 1 ＝C 21 ；
The high-pass filter network 2 comprises a capacitor C 22 An inductor L 2 Capacitor C 3 Port 1 HP2 、2 HP2 And a reference ground G, the topology of the filter network 1 is identical to that of the Balun high-pass filter network of the invention, and the values of the inductance and the capacitance at the corresponding positions of the two high-pass filter networks are respectively equal, namely L 2 ＝L 1 ， C 22 ＝C 1 ，C 3 ＝C 21 ；
The low-pass filter network 1 comprises an inductor L 3 Capacitor C 4 Inductor L 41 Port 1 LP1 、2 LP1 And ground reference G, wherein port 1 LP1 From terminal 1 LP1 And 1' LP1 Formation of port 2 LP1 By terminal 2 LP1 And 2' LP1 Is constituted of terminal 1' LP1 And 2' LP1 Are all electrically connected with a reference ground G, an inductor L 3 And L 41 Are sequentially connected in series to the terminal 1 LP1 And terminal 2 LP1 Between, capacitance C 4 Electrically connected to the inductor L 3 And L 41 Between the connection point of (3) and a reference ground G, an inductance L 3 Capacitor C 4 And an inductance L 41 Form a T-network and an inductance L 3 And L 41 Are equal in inductance value, i.e. L 3 ＝L 41 ；
The low-pass filter network 2 comprises an inductance L 42 Capacitor C 5 Inductor L 5 Port 1 LP2 、2 LP2 And a reference ground G, the low-pass filter network 1 in Balun of the invention has the same topological structure, and the values of the inductance and the capacitance at the corresponding positions of the two low-pass filter networks are respectively equal, namely L 42 ＝L 3 ， L 5 ＝L 41 ，C 5 ＝C 4 。
The external load impedance Z comprises a balanced load impedance R of the balanced port B And load impedance R of unbalanced port UN Wherein R is B And R UN Resistance value R of B And R UN Are all real numbers;
balanced load impedance R of balanced port B Electrically connected to terminals 2 and 3;
unbalanced port load impedance R UN Electrically connected to terminals 1 and 1'.
Capacitor C 21 And a capacitor C 22 Is connected in seriesRelation, capacitance C 21 And a capacitor C 22 Can be equivalent to a capacitor C 2 The capacitance value relationship is C 21 ＝C 22 ＝2C 2 ；
Inductor L 41 And an inductance L 42 In series relationship, inductance L 41 And an inductance L 42 Can be equivalent to an inductor L 4 The relation of inductance is L 41 ＝L 42 ＝L 4 /2；
The target center working frequency of balun design is f 0 Then ω is 0 ＝2×π×f 0 . The inductance and capacitance values must also satisfy the following relationship:
the first embodiment is as follows: balun with a central operating frequency of 3.8GHz and balanced (differential) and unbalanced (single-ended) load impedances of 100 omega and 50 omega, respectively
According to the design method, the following parameters are calculated
L 1 ＝L 2 ＝4.1883nH，L 3 ＝L 5 ＝1.2267nH，L 4 ＝2.4534nH， C 1 ＝C 3 ＝1.4300pF，C 2 ＝0.7150pF，C 4 ＝C 5 ＝0.4188pF。
As can be seen from FIG. 5, the frequency range is 1.763-8.19 GHz when dBS (1,1) < -10dB according to the design method.
As can be seen from fig. 6, according to the design method, | dBS (2,1) -dBS (3,1) | <1.5dB, the frequency range is 2.673-5.401 GHz.
As can be seen from fig. 7, according to the design method, | phase (S (2,1)) -phase (S (3,1)) | -180 ° | <20 °, the frequency range is 2.567-5.625 GHz.
To sum up: aiming at the design target, the LC balun circuit case designed by the method has the working frequency range of 2.673-5.401GHz and the relative bandwidth of 67.6 percent, thereby achieving the design target of the broadband working bandwidth.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be able to cover the technical solutions and the inventive concepts of the present invention within the technical scope of the present invention.
Claims (6)
1. An LC balun circuit is characterized by comprising high-pass filter networks 1 and 2, low-pass filter networks 1 and 2, ports 1, 2 and 3 and a reference ground G, wherein the high-pass filter networks 1 and 2 and the low-pass filter networks 1 and 2 are both two-port networks, the ports 1, 2 and 3 are unbalanced ports which are externally connected in the invention and respectively comprise terminals 1 and 1 ', terminals 2 and 2', and terminals 3 and 3 ', the terminals 1', 2 'and 3' are electrically connected with the reference ground G, meanwhile, the terminals 2 and 3 form balanced ports which are electrically connected with an external balanced system, and the port 1 is electrically connected with the external unbalanced system;
the high-pass filter network 1 comprises a capacitor C 1 Inductor L 1 Capacitor C 21 Port 1 HP1 、2 HP1 And ground G, where port 1 HP1 From terminal 1 HP1 And 1' HP1 Formation of port 2 HP1 By terminal 2 HP1 And 2' HP1 Is constituted of terminal 1' HP1 And 2' HP1 Are all electrically connected with a reference ground G, a capacitor C 1 And C 21 Are sequentially connected in series with the terminal 1 HP1 And terminal 2 HP1 Between, inductance L 1 Electrically connected to the capacitor C 1 And C 21 Between the connection point of (C) and a reference ground G, a capacitance C 1 An inductor L 1 And a capacitor C 21 Form a T-network, and a capacitor C 1 And C 21 Are equal in capacitance value, i.e. C 1 ＝C 21 ；
The high-pass filter network 2 comprises a capacitor C 22 Inductor L 2 Capacitor C 3 Port 1 HP2 、2 HP2 And a reference ground G, the topology of the filter network 1 is identical to that of the Balun high-pass filter network of the invention, and the values of the inductance and the capacitance at the corresponding positions of the two high-pass filter networks are respectively equal, namely L 2 ＝L 1 ，C 22 ＝C 1 ，C 3 ＝C 21 ；
The low-pass filter network 1 comprises an inductor L 3 Capacitor C 4 Inductor L 41 Port 1 LP1 、2 LP1 And ground reference G, wherein port 1 LP1 From terminal 1 LP1 And 1' LP1 Formation of port 2 LP1 By terminal 2 LP1 And 2' LP1 Is constituted of terminal 1' LP1 And 2' LP1 Are all electrically connected with a reference ground G, an inductor L 3 And L 41 Are sequentially connected in series with the terminal 1 LP1 And terminal 2 LP1 Between, capacitance C 4 Electrically connected to the inductor L 3 And L 41 Between the connection point of (3) and a reference ground G, an inductance L 3 Capacitor C 4 And an inductance L 41 Form a T-network and an inductance L 3 And L 41 Are equal in inductance value, i.e. L 3 ＝L 41 ；
The low-pass filter network 2 comprises an inductor L 42 Capacitor C 5 Inductor L 5 Port 1 LP2 、2 LP2 And a reference ground G, the low-pass filter network 1 in Balun of the invention has the same topological structure, and the values of the inductance and the capacitance at the corresponding positions of the two low-pass filter networks are respectively equal, namely L 42 ＝L 3 ，L 5 ＝L 41 ，C 5 ＝C 4 。
2. An LC balun circuit as claimed in claim 1 wherein port 1 of said high pass filter network 1 HP1 And port 1 of said low-pass filter network 1 LP1 Connected in parallel to port 1 of the present invention;
port 2 of the high-pass filter network 1 HP1 And port 1 of said high-pass filter network 2 HP2 Connecting;
port 2 of the high-pass filter network 2 HP2 Connected to port 2 of the present invention;
port 2 of the low-pass filter network 1 LP1 And port 1 of said low-pass filter network 2 LP2 Connecting;
port 2 of the low-pass filter network 2 LP2 Connected to port 3 of the present invention.
3. An LC balun circuit as claimed in claims 1 and 2,
the external load impedance Z comprises a balanced load impedance R of a balanced port B And load impedance R of unbalanced port UN Wherein R is B And R UN Resistance value R of B And R UN Are all real numbers;
balanced load impedance R of balanced port B Electrically connected to terminals 2 and 3;
unbalanced port load impedance R UN Electrical connections are made to terminals 1 and 1'.
4. An LC balun circuit as claimed in claims 1 and 2 wherein said capacitor C 21 And said capacitor C 22 In series relation, the capacitor C 21 And said capacitor C 22 Can be equivalent to a capacitor C 2 The capacitance value relationship is C 21 ＝C 22 ＝2C 2 。
5. An LC balun circuit as claimed in claim 1 or 2 wherein said inductance L is 41 And the inductance L 42 In series relation, the inductance L 41 And the inductance L 42 Can be equivalent to an inductor L 4 The relation of inductance is L 41 ＝L 42 ＝L 4 /2。
6. An LC balun circuit as claimed in claim 1 or 2 wherein the balun design target center operating frequency is f 0 Then ω is 0 ＝2×π×f 0 . The inductance and capacitance values must also satisfy the following relationship:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210613254.5A CN115133898A (en) | 2022-05-31 | 2022-05-31 | LC balun circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210613254.5A CN115133898A (en) | 2022-05-31 | 2022-05-31 | LC balun circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115133898A true CN115133898A (en) | 2022-09-30 |
Family
ID=83378146
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210613254.5A Pending CN115133898A (en) | 2022-05-31 | 2022-05-31 | LC balun circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115133898A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116470253A (en) * | 2023-04-23 | 2023-07-21 | 南通至晟微电子技术有限公司 | Compact balanced broadband filter |
-
2022
- 2022-05-31 CN CN202210613254.5A patent/CN115133898A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116470253A (en) * | 2023-04-23 | 2023-07-21 | 南通至晟微电子技术有限公司 | Compact balanced broadband filter |
| CN116470253B (en) * | 2023-04-23 | 2023-10-31 | 南通至晟微电子技术有限公司 | Compact balanced broadband filter |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US7327131B2 (en) | Balun transformer and low-pass filter | |
| Hou et al. | Design of Compact 90$^{\circ} $ and 180$^{\circ} $ Couplers With Harmonic Suppression Using Lumped-Element Bandstop Resonators | |
| CN112563712B (en) | Terminating complex impedance directional coupler with harmonic suppression function and design method | |
| US20040169566A1 (en) | Frequency-selective balun transformer | |
| US8552782B1 (en) | Quadrature phase network | |
| CN112366436A (en) | Filtering type crossing directional coupler with broadband pass response and design method | |
| CN115133898A (en) | LC balun circuit | |
| Lin et al. | High-linearity 5.3-7.0 GHz 3-pole tunable bandpass filter using commercial RF MEMS capacitors | |
| CN106450601B (en) | LTCC filter switch based on coupling control | |
| CN210093186U (en) | Dual complementary duplex filter | |
| Yang et al. | Compact and high-performance low-temperature co-fired ceramic balun filter using the hybrid resonator and symmetric four-port network | |
| CN111403378A (en) | Thin film integrated passive element IPD broadband radio frequency balun chip | |
| CN113964467B (en) | Balance-unbalanced type in-phase filtering power divider based on three-wire coupling | |
| CN108011168B (en) | Novel Wilkinson power divider capable of terminating complex impedance | |
| CN217607004U (en) | Broadband balun | |
| CN217590768U (en) | Balance-unbalance converter | |
| CN115967369A (en) | Ultra-wideband phase shifter based on band-pass filter network | |
| CN115001432A (en) | Balun circuit | |
| CN110856339B (en) | Planar circuit for signal cross transmission | |
| WO2023245497A1 (en) | Broadband lc balun | |
| CN111384908A (en) | Power divider circuit, power divider and design method of power divider circuit | |
| CN114243245B (en) | Broadband subminiature coupler based on folding line and non-equal-width coupling three lines | |
| CN219018787U (en) | Radio frequency matching circuit | |
| CN216565089U (en) | Impedance matching circuit and antenna | |
| CN220873811U (en) | VHF double-circuit integrated combiner |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |