Simplified circuit replacing Balun
By designing a simplified Balun circuit, using the characteristics of capacitors and inductors, the problems of debugging complexity and high cost of existing Balun circuits in mobile phone environments are solved, and the sensitivity improvement and communication quality improvement is achieved.
Patent Information
- Application Number
- CN202421009843.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-08
- Publication Date
- 2024-12-27
- Estimated Expiration
- 2034-05-08
AI Technical Summary
The existing Balun circuit is complex in the mobile phone product environment, the LAYOUT is difficult, the production cost is high, and it is difficult to achieve equal-length differential routing, which affects the communication quality.
A simplified circuit is designed to replace Balun, which is connected to inductor L6030 through capacitor C6570. Inductor L6040 is a normally closed contact, capacitor C6580 is 0R, capacitor C6590 is a normally closed capacitor, capacitor C6570 is 2.7pF, and inductor L6030 is 2.4nH. The circuit structure is simplified, production costs are reduced, and commissioning sensitivity is improved.
The simplification of LAYOUT is achieved, the production cost is reduced, and the debugging sensitivity is improved, so that the phase difference between RF_RX_GSM_HB_N and RF_RX_GSM_HB_P signals can be adjusted to close to 180 degrees, improving communication quality.
Smart Images
Figure CN222262714U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of radio frequency circuit reception, and more specifically to a simplified circuit replacing Balun. Background Art
[0002] Balun (balun, short for "balanced to unbalanced") is a common circuit component. Its main function is to convert a single-ended signal into a differential signal. Baluns are implemented in different ways in different circuit applications. The most common one is to use a transformer with one end of the primary side grounded. In antenna engineering, it is more common to use a quarter-wavelength coaxial cable as a balun.
[0003] The existing Balun-saving circuit has the problem of high requirements for PCB routing and large PCB board space. The existing Balun-saving circuit has high cost and requires differential routing of 50 ohms for single-end and 100 ohms for differential, and equal length. The actual PCB routing is difficult to achieve in the product environment of mobile phones. The space is very limited and can only be as equal as possible. The existing Balun-saving circuit is complicated to debug, and GSM1800 1900 cannot be balanced well. Either 1800 is better or 1900 is better. It is inconvenient to use and has high production costs. Utility Model Content
[0004] The technical problem to be solved by the utility model is that the existing Balun circuit is complicated to debug, the actual LAYOUT is difficult, and the production cost is high. In view of the above-mentioned defects of the prior art, a simplified circuit for replacing Balun is provided, including: one end of capacitor C6570 is respectively connected to one end of inductor L6030 and RF_RX_GSM_HB_N signal line, the other end of inductor L6030 is respectively connected to one end of capacitor C6540, one end of capacitor C6550, and one end of capacitor C6580, the other end of capacitor C6580 is respectively connected to one end of inductor L6040 and RF_RX_GSM_HB_P signal line, the other end of inductor L6040 is connected to one end of capacitor C6590, the other end of capacitor C6540 is connected to one end of capacitor C6530, and the other end of capacitor C6530 is connected to one end of inductor L6020.
[0005] Preferably, the other end of the capacitor C6550 is grounded.
[0006] Preferably, the other end of the inductor L6020 is grounded.
[0007] Preferably, the other end of the capacitor C6570 is grounded.
[0008] Preferably, the other end of the capacitor C6590 is grounded.
[0009] Preferably, the capacitor C6580 is 0R.
[0010] Preferably, the inductor L6040 is NC.
[0011] Preferably, the capacitor C6590 is NC.
[0012] Preferably, the capacitor C6570 is 2.7 pF.
[0013] Preferably, the inductor L6030 is 2.4 nH.
[0014] The simplified circuit for replacing Balun of the utility model has the following beneficial effects: by adopting one end of capacitor C6570 to be respectively connected to one end of inductor L6030 and RF_RX_GSM_HB_N signal line, the other end of inductor L6030 is respectively connected to one end of capacitor C6540, one end of capacitor C6550 and one end of capacitor C6580, the other end of capacitor C6580 is respectively connected to one end of inductor L6040 and RF_RX_GSM_HB_P signal line, the other end of inductor L6040 is connected to one end of capacitor C6590, the other end of capacitor C6540 is connected to one end of capacitor C6530, and the other end of capacitor C6530 is connected to one end of inductor L6020, the simplified circuit for replacing Balun is convenient for LAYOUT, low in production cost, and easy to debug. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without creative work. The utility model will be further described below in combination with the drawings and embodiments. In the drawings:
[0016] Figure 1 It is a circuit diagram of a simplified circuit of the utility model replacing Balun;
[0017] Figure 2 This is the PCB LAYOUT diagram of the provincial Balun circuit before simplification. DETAILED DESCRIPTION
[0018] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.
[0019] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.
[0020] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the utility model.
[0021] See also Figure 1 , is a circuit diagram of a simplified circuit of the utility model replacing Balun. Figure 1 As shown, in the simplified circuit replacing Balun provided in the first embodiment of the utility model, at least a simplified circuit replacing Balun is included, including: one end of capacitor C6570 is respectively connected to one end of inductor L6030 and RF_RX_GSM_HB_N signal line, the other end of inductor L6030 is respectively connected to one end of capacitor C6540, one end of capacitor C6550, and one end of capacitor C6580, the other end of capacitor C6580 is respectively connected to one end of inductor L6040 and RF_RX_GSM_HB_P signal line, the other end of inductor L6040 is connected to one end of capacitor C6590, the other end of capacitor C6540 is connected to one end of capacitor C6530, and the other end of capacitor C6530 is connected to one end of inductor L6020. The other end of capacitor C6550 is grounded. The other end of inductor L6020 is grounded. The other end of capacitor C6570 is grounded. The other end of capacitor C6590 is grounded.
[0022] In the field of wireless communication, especially in GSM (Global System for Mobile Communications) technology, RF_RX_GSM_HB_P and RF_RX_GSM_HB_N are two crucial parameters. They are not only related to the communication quality, but also directly affect the network coverage and user experience.
[0023] RF stands for radio frequency, which is the key part of wireless communication responsible for transmitting signals. RX stands for receive, which refers to the ability of the device to receive signals. GSM_HB refers to the high frequency band of GSM, which is the main frequency band used to transmit data in the GSM network. The last P and N stand for positive and negative poles, respectively, which refers to the positive and negative phases of the signal.
[0024] RF_RX_GSM_HB_P and RF_RX_GSM_HB_N represent the positive phase and negative phase received signal strength in the GSM high frequency band respectively. These two parameters play a vital role in wireless communication. They not only reflect the ability of the device to receive signals, but also directly affect the communication quality and network coverage.
[0025] In actual applications, the values of RF_RX_GSM_HB_P and RF_RX_GSM_HB_N directly determine whether the device can successfully receive the signal and the quality of the received signal. If the values of these two parameters are high, it means that the device has a strong ability to receive signals and the communication quality will be improved accordingly. On the contrary, if the values of these two parameters are low, the device's ability to receive signals will be weakened and the communication quality will be affected.
[0026] In addition, these two parameters also have a direct impact on network coverage. In base station layout and signal coverage optimization, the values of RF_RX_GSM_HB_P and RF_RX_GSM_HB_N are key reference indicators. By adjusting base station parameters and antenna angles, the values of these two parameters can be optimized, thereby improving network coverage and communication quality.
[0027] In specific implementation, capacitor C6580 is 0R. The basic function of a capacitor is to store and release electrical energy, and its value directly affects the performance and stability of the circuit. Here, capacitor C6580 is set to 0R, which means that the capacitance value of 0R does not mean that the capacitor is completely ineffective, but that the impedance value of the capacitor is close to 0, that is, the blocking effect of the capacitor in the circuit is almost negligible. This characteristic makes it play a vital role in some circuits that require high-frequency signal transmission or precise signal control.
[0028] In high-frequency circuits, the impedance of capacitors decreases as the frequency increases, which means that when high-frequency signals are transmitted, the blocking effect of capacitors becomes more obvious. If a capacitor with a capacitance value of 0R is used, this blocking effect can be greatly reduced, thereby improving the signal transmission efficiency. This is undoubtedly very important for some electronic devices that need to run at high speeds.
[0029] In addition, capacitors with a capacitance value of 0R can also play an important role in areas where precise signal control is required. For example, in some precision analog circuits, a small change in capacitance value may cause signal distortion or drift. Using capacitors with a capacitance value of 0R can effectively reduce this effect, thereby improving the stability and accuracy of the circuit.
[0030] Setting capacitor C6580 to 0R can improve signal transmission efficiency, reduce signal distortion and drift, and improve circuit stability and accuracy.
[0031] In practice, the inductor L6040 is NC. NC refers to the Normal Close contact. This means that in the default or unpowered state, the NC contact is closed, and under certain conditions (such as after power is applied), the contact will be open. This is in contrast to the NO (Normally Open) contact, which is open by default and will only close when certain conditions are met. Inductance, as a property of a closed loop, describes the magnetic field induced by the coil after the current passes through it. This induced magnetic field will generate an induced current to resist the original current passing through the coil. This interaction between the current and the coil is the inductance, which has the unit of Henry (H).
[0032] In practical applications, inductors, especially coils with iron cores, are the main manifestation of inductance. Inductors hinder the change of current, block direct current, pass low frequencies, and block high frequencies. This characteristic makes inductors play a pivotal role in circuit design. When an inductor is NC (normally closed), it means that the inductor is closed when it is not powered. However, once powered, the effect of the electromagnetic coil will cause the inductor to open. In the field of communications, inductors are used for filtering and impedance matching to ensure clear and stable signals.
[0033] In specific implementation, capacitor C6590 is NC. Normally closed capacitors, also known as fixed capacitors or non-adjustable capacitors, have the greatest feature that their capacitance will not change once they are manufactured. This type of capacitor has strong stability. Normally closed capacitors can not only store and release electrical energy, but also play a variety of roles in circuits such as filtering, DC isolation, and coupling. In high-frequency circuits, normally closed capacitors can effectively prevent low-frequency signals from passing through, ensuring the normal operation of the circuit. In radio communications, normally closed capacitors are used to adjust frequency, filter, and match impedance to ensure clear and stable signals.
[0034] In a specific implementation, the capacitor C6570 is 2.7 pF and the inductor L6030 is 2.4 nH.
[0035] Figure 2 This is the schematic diagram of the PCB LAYOUT of the Balun circuit before simplification. Figure 2 As shown, it is impossible to achieve the requirement of equal length for actual PCB routing in the product environment of mobile phones. The space is very limited, so they can only be as equal as possible.
[0036] Obviously, RF_RX_GSM_HB_P is a little bit longer than RF_RX_GSM_HB_N, so the phase between the two lines is doomed to be impossible to have a phase difference of 180 degrees from the beginning. The classic matching is RF_RX_GSM_HB_N series L6030 2.7nH, and C65702.7pF. Ideally, the phase of RF_RX_GSM_HB_N is 90 degrees ahead of RF_RX_GSM_HB_P series C65802.7pF, and L60402.7nH. Ideally, the phase of RF_RX_GSM_HB_N lags 90 degrees. C6590 100pF is equivalent to a 0R short circuit to ground for GSM1800 1900 high frequency. The capacitor is used to isolate the DC, and the impact can be ignored. The matching value is designed to have a phase difference of 180 degrees, but the actual inductor L6040 2.7nH and L6030 2.7nH materials have a little bit of precision difference, and the capacitor C6570 2.7pF and C6580 2.7pF materials also have a little bit of precision difference, so the phase will deviate greatly from 180 degrees due to the unequal length and material precision difference. Theoretically, the actual value fluctuates between 0 and 180 degrees. The measured sensitivity also verifies that the sensitivity is not high and cannot be improved by adjusting the inductor and capacitor values.
[0037] Through the design of the above embodiment, the utility model optimizes the circuit differential matching by using three materials, and the original differential matching uses five materials. RF_RX_GSM_HB_N is connected in series with L6030 2.7nH, and C6570 2.7pF is retained in parallel. C6580 is changed to 0R, L6040 is directly normally closed NC, and C6590 is not used and is also selected as normally closed NC. After this change, unequal lengths have no effect. As long as the single-ended differential routing is 50 ohms and the differential is 100 ohms, the worst case can ensure that the phase difference between RF_RX_GSM_HB_N and RF_RX_GSM_HB_P is 90 degrees. By adjusting the matching of RF_RX_GSM_HB_N to be connected in series with L6030 2.4nH and C6570 2.7pF, it can be easily adjusted to nearly 180 degrees. The measured sensitivity has also verified that the sensitivity is indeed greatly improved by 3-4DB, which is comparable to that using Balun The SAW values are almost the same, which means that the RF_RX_GSM_HB_P and RF_RX_GSM_HB_N traces are only differential and there is no need to worry about equal length.
[0038] Through the design of the above embodiments, the utility model has the beneficial effects as follows: by adopting one end of the capacitor C6570 to be respectively connected to one end of the inductor L6030 and the RF_RX_GSM_HB_N signal line, the other end of the inductor L6030 is respectively connected to one end of the capacitor C6540, one end of the capacitor C6550, and one end of the capacitor C6580, the other end of the capacitor C6580 is respectively connected to one end of the inductor L6040 and the RF_RX_GSM_HB_P signal line, the other end of the inductor L6040 is connected to one end of the capacitor C6590, the other end of the capacitor C6540 is connected to one end of the capacitor C6530, and the other end of the capacitor C6530 is connected to one end of the inductor L6020, a simplified circuit that can replace Balun is convenient for LAYOUT, has low production cost, and is easy to debug.
[0039] The present invention is described according to specific embodiments, but those skilled in the art should understand that various changes and equivalent substitutions can be made without departing from the scope of the present invention. In addition, in order to adapt to specific occasions of the present invention technology, many modifications can be made to the present invention without departing from its protection scope. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all embodiments that fall within the scope of protection of the claims.
Claims
1. A simplified circuit to replace Balun, characterized in that: include: One end of capacitor C6570 is respectively connected to one end of inductor L6030 and the RF_RX_GSM_HB_N signal line, the other end of inductor L6030 is respectively connected to one end of capacitor C6540, one end of capacitor C6550, and one end of capacitor C6580, the other end of capacitor C6580 is respectively connected to one end of inductor L6040 and the RF_RX_GSM_HB_P signal line, the other end of inductor L6040 is connected to one end of capacitor C6590, the other end of capacitor C6540 is connected to one end of capacitor C6530, and the other end of capacitor C6530 is connected to one end of inductor L6020.
2. The simplified circuit for replacing Balun according to claim 1, characterized in that: The other end of the capacitor C6550 is grounded.
3. The simplified circuit for replacing Balun according to claim 1, characterized in that: The other end of the inductor L6020 is grounded.
4. The simplified circuit for replacing Balun according to claim 1, characterized in that: The other end of the capacitor C6570 is grounded.
5. The simplified circuit for replacing Balun according to claim 1, characterized in that: The other end of the capacitor C6590 is grounded.
6. The simplified circuit for replacing Balun according to any one of claims 1 to 5, characterized in that: The capacitor C6580 is 0R.
7. The simplified circuit for replacing Balun according to any one of claims 1 to 5, characterized in that: The inductor L6040 is NC.
8. The simplified circuit for replacing Balun according to any one of claims 1 to 5, characterized in that: The capacitor C6590 is NC.
9. The simplified circuit for replacing Balun according to any one of claims 1 to 5, characterized in that: The capacitor C6570 is 2.7 pF.
10. The simplified circuit for replacing Balun according to any one of claims 1 to 5, characterized in that: The inductor L6030 is 2.4nH.