WO2023020097A1

WO2023020097A1 - Harmonic suppression matching circuit structure suitable for balun, and power amplifier

Info

Publication number: WO2023020097A1
Application number: PCT/CN2022/099448
Authority: WO
Inventors: 赵罡; 龙华
Original assignee: 深圳飞骧科技股份有限公司
Priority date: 2021-08-19
Filing date: 2022-06-17
Publication date: 2023-02-23
Also published as: CN215912080U

Abstract

A harmonic suppression matching circuit structure suitable for a balun, and a power amplifier. The circuit structure comprises a balun (1), a first tuning unit (2) and a second tuning unit (3). The balun (1) comprises a primary coupling coil (N1), a first secondary coupling coil (N2) and a second secondary coupling coil (N3), wherein the primary coupling coil (N1) is connected between an unbalanced signal port (T1) and a grounding end; one end of the first secondary coupling coil (N2) is connected to a first balanced signal port (T2); one end of the second secondary coupling coil (N3) is connected to a second balanced signal port (T3); and a connection point of the first secondary coupling coil (N2) and the second secondary coupling coil (N3) is connected to the grounding end. The first tuning unit (2) is connected between the first balanced signal port (T2) and the second balanced signal port (T3). The second tuning unit (3) is connected between the unbalanced signal port (T1) and the grounding end. Given that the good balance of a balun is maintained, the higher harmonic suppression capability of the balun can be effectively improved, such that system requirements of 5G-NR are met.

Description

A Harmonic Suppression Matching Circuit Structure and Power Amplifier Suitable for Balun

technical field

The present application relates to the technical field of power amplification, in particular to a harmonic suppression matching circuit structure and a power amplifier suitable for a balun.

Background technique

A balun (English balun) is a three-port device, or a broadband radio frequency transmission line transformer that realizes the connection between a balanced transmission line circuit and an unbalanced transmission line circuit by converting a matched input into a differential output. The function of the balun is to make the system have different impedance or compatible with differential/single-ended signaling, and it is used in modern communication systems such as mobile phones and data transmission networks.

5G NR, a global 5G standard based on a new OFDM air interface design, is also a very important foundation for the next generation of cellular mobile technology. 5G technology will achieve ultra-low latency and high reliability. The main advantage of 5G networks is that the data transfer rate is much higher than previous cellular networks, up to 10Gbit/s, which is faster than current wired Internet and 100 times faster than previous 4G LTE cellular networks. Another advantage is lower network latency (faster response time), below 1 millisecond compared to 30-70 milliseconds for 4G.

In order to achieve such a high data transmission rate, higher linearity requirements are put forward for the power amplifier in the RF front-end module. The push-pull RF amplifier structure is more and more used in the design of 5G-NR RF power amplifiers because of its high linear power. The balun is designed at the output port of the push-pull RF amplifier, which has impedance matching and harmonic suppression. And so on, it plays a key role in the performance of the whole module.

Because the 5G-NR RF front-end module has high transmit power, the high-order harmonics generated are also synchronously larger, and the traditional balun does not have good harmonic suppression capabilities.

Utility model content

An embodiment of the present application provides a harmonic suppression matching circuit structure suitable for a balun, including a balun, a first tuning unit, and a second tuning unit. The balun includes a main coupling coil, a first secondary coupling coil, and a second A secondary coupling coil, the main coupling coil is connected between the unbalanced signal port and the ground terminal, one end of the first secondary coupling coil is connected to the first balanced signal port, and one end of the second secondary coupling coil is connected to the second balanced signal port Signal port, the connection point of the first secondary coupling coil and the second secondary coupling coil is connected to the ground terminal; the first tuning unit is connected between the first balanced signal port and the second balanced signal port ; The second tuning unit is connected between the unbalanced signal port and the ground terminal.

According to some embodiments, the first tuning unit includes a first capacitor connected between the first balanced signal port and the second balanced signal port.

According to some embodiments, the first tuning unit further includes a first inductor, and the first inductor and the first capacitor are connected in series between the first balanced signal port and the second balanced signal port.

According to some embodiments, the first capacitor and the first inductor resonate at a second harmonic frequency.

According to some embodiments, the second tuning unit includes a second capacitor connected between the unbalanced signal port and the ground terminal.

According to some embodiments, the second tuning unit further includes a second inductor, and the second inductor and the second capacitor are connected in series between the unbalanced signal port and the ground terminal.

According to some embodiments, the second capacitor and the second inductor resonate at a third harmonic frequency.

According to some embodiments, the working frequency band of the balun is adjusted by tuning the first capacitance of the first tuning unit and the second capacitance of the second tuning unit.

The embodiment of the present application also provides a power amplifier, including the above-mentioned harmonic suppression matching circuit structure suitable for a balun.

The technical solution provided by the embodiment of the present application proposes a harmonic suppression matching circuit structure suitable for the balun. Using this structure can effectively improve the balun's high-order harmonics under the premise of maintaining a good balance of the balun. The ability to suppress, so as to meet the system requirements of 5G-NR, and can maintain a good balance of the balun.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings without creative effort.

FIG. 1 is a schematic structural diagram of a balun matching circuit in the prior art.

FIG. 2 is a schematic diagram of the Balun balance of the structure in FIG. 1 .

FIG. 3 is a schematic diagram of the harmonic suppression capability of the structure in FIG. 1 .

FIG. 4 is a schematic structural diagram of a harmonic suppression matching circuit suitable for a balun according to an embodiment of the present application.

FIG. 5 is a schematic structural diagram of another harmonic suppression matching circuit suitable for a balun according to an embodiment of the present application.

FIG. 6 is a schematic structural diagram of another harmonic suppression matching circuit suitable for a balun according to an embodiment of the present application.

FIG. 7 is a schematic diagram of the Balun balance of the structure in FIG. 6 .

FIG. 8 is a schematic diagram of the harmonic suppression capability of the structure in FIG. 6 .

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of this application.

It should be understood that the terms "comprising" and "comprising" used in the specification and claims of this application indicate the presence of described features, integers, steps, operations, elements and/or components, but do not exclude one or more other Presence or addition of features, wholes, steps, operations, elements, components and/or collections thereof.

As shown in Figure 1, port 1 is an unbalanced port, and

ports

2 and 3 are balanced ports. The capacitor C1 between the balanced ends and the capacitor C2 between the unbalanced ends play a tuning role, so that the balun works in different frequency bands. The balun Xfer1 is composed of three inductors, which are the main coil inductor N1, and the additional coil inductors N2 and N3. In order to make the balance ends differ by 180°, the center ports of N1 and N2 coils are grounded.

Design a 2.5GHz balun structure, as shown in Figure 2.

As shown in Figure 2, the abscissa is the frequency, the unit is GHz, and the ordinate is the phase from the two balanced ends to the unbalanced end. phase(S2,1) represents the phase from the first balanced end to the unbalanced end, and phase(S3,1) represents the phase from the second balanced end to the unbalanced end.

At point m4, the frequency is 2.5GHz, the phase from the first balanced end to the unbalanced end is 51.048°, and the phase from the second balanced end to the unbalanced end is 128.952°.

It can be seen that the balance of the balun is good, and the difference between the two balanced ports is 180°.

The frequency response of the balun is shown in Figure 3. The abscissa is the frequency in GHz, and the ordinate is the insertion loss, dB(S2,1), which represents the insertion loss from the first balanced end to the unbalanced end. dB(S3,1), represents the insertion loss from the second balanced end to the unbalanced end.

At point m1, the frequency is 2.5GHz, the insertion loss from the first balanced end to the unbalanced end is -3.010dB, and the insertion loss from the second balanced end to the unbalanced end is -3.010dB. At point m2, the frequency is 5GHz, the insertion loss from the first balanced end to the unbalanced end is -10.511dB, and the insertion loss from the second balanced end to the unbalanced end is -10.511dB. At point m3, the frequency is 7.5GHz, the insertion loss from the first balanced end to the unbalanced end is -21.811dB, and the insertion loss from the second balanced end to the unbalanced end is -21.811dB.

The insertion loss from the balanced terminal to the unbalanced terminal is -3dB, the second-order harmonic suppression capability is -10dB, and the third-order harmonic suppression capability is -21dB.

The circuit structure includes a balun 1 , a first tuning unit 2 and a second tuning unit 3 .

The balun 1 includes a primary coupling coil N1, a first secondary coupling coil N2 and a second secondary coupling coil N3. The main coupling coil N1 is connected between the unbalanced signal port T1 and the ground. One end of the first secondary coupling coil N2 is connected to the first balanced signal port T2. One end of the second secondary coupling coil N3 is connected to the second balanced signal port T3. The connection point between the first secondary coupling coil N2 and the second secondary coupling coil N3 is connected to the ground terminal; the first tuning unit 2 is connected between the first balanced signal port T2 and the second balanced signal port T3. The second tuning unit 3 is connected between the unbalanced signal port T1 and the ground.

The first tuning unit 2 includes a first capacitor C1, and the first capacitor C1 is connected between the first balanced signal port T2 and the second balanced signal port T3.

According to some embodiments, the first tuning unit 2 includes a first capacitor C1 and a first inductor, as shown in FIG. 5 . The first inductor L1 and the first capacitor C1 are connected in series between the first balanced signal port T2 and the second balanced signal port T3. The first capacitor C1 and the first inductor L1 resonate at the second-order harmonic frequency, which can improve the ability to suppress the second-order harmonic.

According to some embodiments, the second tuning unit 3 includes a second capacitor C2, and the second capacitor C2 is connected between the unbalanced signal port T1 and the ground terminal.

According to some embodiments, the second tuning unit 3 includes a second capacitor C2 and a second inductor L2. As shown in FIG. 6 , the second inductor L2 and the second capacitor C2 are connected in series between the unbalanced signal port T1 and the ground. The second capacitor C2 and the second inductor L2 resonate at the third-order harmonic frequency, which can improve the ability to suppress the third-order harmonic.

By tuning the first capacitor C1 of the first tuning unit 2 and the second capacitor C2 of the second tuning unit 3 , the working frequency band of the balun 1 is adjusted.

Design a 2.5GHz balun structure as shown in Figure 6, and the balun balance is shown in Figure 7.

As shown in FIG. 7 , the abscissa is the frequency, and the unit is GHz, and the ordinate is the phase from the two balanced terminals to the unbalanced terminal. phase(S2,1), represents the phase from the first balanced end to the unbalanced end, and the curve shown in the figure is 10, and phase(S3,1), represents the phase from the second balanced end to the unbalanced end, as shown in the figure The curve is 20.

At point m1, the frequency is 2.5GHz, the phase phase (S2,1) from the first balanced end to the unbalanced end is 55.359°, and the phase phase (S3,1) from the second balanced end to the unbalanced end is 124.641°.

An important standard indicator of the balun is its balance, that is, two balanced outputs (one is an inverting 180° output and the other is a non-inverting output) and the ideal state of "equal power level, 180° phase difference" the degree of proximity. The degree to which the phase angle difference between the two outputs deviates from 180° is called the phase imbalance of the balun. The quality of the balun balance directly affects the performance of the RF power amplifier. It can be seen that the balance of the balun is good, and the difference between the two balanced ports is 180°.

The frequency response of the balun is shown in Figure 8. The abscissa is the frequency in GHz, and the ordinate is the insertion loss, dB(S2,1), which represents the insertion loss from the first balanced end to the unbalanced end. dB(S3,1), represents the insertion loss from the second balanced end to the unbalanced end.

At point m2, the frequency is 2.5GHz, the insertion loss from the first balanced end to the unbalanced end is -3.04dB, and the insertion loss from the second balanced end to the unbalanced end is -3.04dB. At point m3, the frequency is 5GHz, the insertion loss from the first balanced port to the unbalanced port is -51.371dB, and the insertion loss from the second balanced port to the unbalanced port is -51.371dB. At point m4, the frequency is 7.5GHz, the insertion loss from the first balanced end to the unbalanced end is -66.836dB, and the insertion loss from the second balanced end to the unbalanced end is -66.836dB.

It can be seen that in this embodiment, the insertion loss from the balanced terminal to the unbalanced terminal is -3dB, the second-order harmonic suppression capability is -51dB, and the third-order harmonic suppression capability is -66dB. Compared with the balun of the prior art, the harmonic suppression capability of the balun is greatly enhanced without sacrificing insertion loss and balance.

An embodiment of the present application also provides a power amplifier, including the harmonic suppression matching circuit structure suitable for a balun as described above.

The above embodiments are only to illustrate the technical ideas of the present application, and cannot limit the protection scope of the application with this. Any changes made on the basis of the technical solutions according to the technical ideas proposed in the application all fall within the protection scope of the application. Inside.

Claims

A harmonic suppression matching circuit structure suitable for a balun, including:

The balun includes a main coupling coil, a first secondary coupling coil and a second secondary coupling coil, the primary coupling coil is connected between the unbalanced signal port and the ground terminal, and one end of the first secondary coupling coil is connected to the first balanced A signal port, one end of the second secondary coupling coil is connected to a second balanced signal port, and the connection point between the first secondary coupling coil and the second secondary coupling coil is connected to a ground terminal;

a first tuning unit connected between the first balanced signal port and the second balanced signal port;

The second tuning unit is connected between the unbalanced signal port and the ground terminal.
The circuit structure according to claim 1, wherein the first tuning unit comprises:

The first capacitor is connected between the first balanced signal port and the second balanced signal port.
The circuit structure according to claim 2, wherein the first tuning unit further comprises:

The first inductor is connected in series with the first capacitor between the first balanced signal port and the second balanced signal port.
The circuit structure of claim 3, wherein said first capacitor and said first inductor resonate at a second harmonic frequency.
The circuit structure according to any one of claims 1 to 4, wherein the second tuning unit comprises:

The second capacitor is connected between the unbalanced signal port and the ground terminal.
The circuit structure according to claim 5, wherein the second tuning unit further comprises:

The second inductor is connected in series with the second capacitor between the unbalanced signal port and the ground terminal.
The circuit structure of claim 6, wherein said second capacitor and said second inductor resonate at a third harmonic frequency.
The circuit structure according to claim 5, wherein the working frequency band of the balun is adjusted by tuning the first capacitance of the first tuning unit and the second capacitance of the second tuning unit.
A power amplifier, comprising the harmonic suppression matching circuit structure applicable to a balun according to any one of claims 1 to 8.