CN106787623B - Noise reduction method of electronic system, electronic system and voltage conversion circuit - Google Patents
Noise reduction method of electronic system, electronic system and voltage conversion circuit Download PDFInfo
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Abstract
The invention discloses a noise reduction method of an electronic system, the electronic system and a voltage conversion circuit, wherein the noise reduction method comprises the following steps: searching and determining elements generating noise on a PCB of the electronic system; for each searched element generating noise, replacing the element with a first element and a second element which are connected in parallel and have the same value, wherein the first element and the second element are the same as the element and are equivalent to the element after being connected in parallel; the first element and the second element are placed on the two sides of the PCB in the same direction, so that the noise generated by the first element and the noise generated by the second element are mutually offset. The noise reduction method can eliminate the vibration noise of electronic system elements, and has simple and easy realization method and lower cost.
Description
The patent application of the invention is a divisional application of Chinese invention patent application with application date of 2014, 08 and 06 and application number of 201410384460.9, named as 'noise reduction method of electronic system, electronic system and voltage conversion circuit'.
Technical Field
The invention relates to the field of noise reduction of electronic systems, in particular to a noise reduction method of an electronic system, the electronic system and a voltage conversion circuit.
Background
According to the piezoelectric effect, the ripple of the electrical signal, i.e. the variation of the voltage, causes the traces of the dielectric, the ripple amplitude and frequency of the electrical signal causing the dielectric ripple to have the same amplitude and frequency.
Electronic systems currently used in the industry include many electronic components, such as resistors, capacitors, etc. Fig. 1 and 2 show the layout of prior art components on a PCB and a schematic diagram of a voltage conversion circuit of an electronic system, and referring to fig. 1, these electronic components are all laid on the PCB of the electronic system, which results in that during the actual operation of the electronic system, when signals with large frequency and large amplitude pass through these components, or due to the ripple of the power supply, vibration of these components is caused, and the noise of the vibration often causes discomfort to users when using electronic products, especially in wearable products such as head-mounted electronic systems and wristbands, such noise is more obvious and seriously affects the comfort and practicability of the products.
Disclosure of Invention
The invention provides a noise reduction method of an electronic system, the electronic system and a voltage conversion circuit, which are used for solving the problem that the comfort and the practicability of a product are influenced by the vibration noise of electronic elements in the electronic system.
According to an aspect of the present invention, there is provided a method of reducing noise of an electronic system, the method comprising:
step S310: searching and determining elements generating noise on a PCB of the electronic system;
step S320: for each searched element generating noise, replacing the element with a first element and a second element which are connected in parallel and have the same value, wherein the first element and the second element are the same as the element and are equivalent to the element after being connected in parallel;
step S330: the first element and the second element are symmetrically placed on both sides of the PCB board, so that noises generated by the first element and the second element are mutually cancelled.
Optionally, step S340 is further included after step S330: noise of the electronic system is detected and determined to be satisfactory.
Optionally, the noise element generating noise comprises one or more of the following elements:
a resistance; a capacitor; an inductance.
Optionally, symmetrically placing the first element and the second element on both sides of the PCB board comprises:
and connecting the first element and the second element by the through hole, wherein the distance from the through hole to two ends of the first element and the second element is the shortest.
According to another aspect of the present invention, there is provided an electronic system including a plurality of components laid out on a PCB, in which a noise generating component is composed of a first component and a second component which are connected in parallel and have equal values;
the first element and the second element are the same as the element and are equivalent to the element after being connected in parallel;
the first element and the second element are symmetrically placed on both sides of the PCB board.
Optionally, the noise element generating noise comprises one or more of the following elements:
a resistance; a capacitor; an inductance.
Optionally, the first and second elements being symmetrically placed on both sides of the PCB board comprises:
and connecting the first element and the second element by the through hole, wherein the distance from the through hole to two ends of the first element and the second element is the shortest.
According to another aspect of the present invention, there is provided a voltage conversion circuit including: the power supply comprises a power supply management chip, MOS (metal oxide semiconductor) transistors Q1 and Q2, a power supply 1, a power supply 2, inductors L2 and L3, capacitors C2, C3, C4 and C5, resistors R2 and R3 and a functional module;
a high-level pin of the power management chip is connected with a grid electrode of the MOS tube Q1; the drain electrode of the MOS tube Q1 is connected with the power supply 1;
the source electrode of the MOS tube Q1 is respectively connected with the switching pin of the power management chip, one end of the inductor L2 and the drain electrode of the MOS tube Q2;
the grid electrode of the MOS tube Q2 is connected with a low level pin of the power management chip, and the source electrode of the MOS tube Q2 is grounded;
one end of the capacitor C2 is connected with the power supply 1, and the other end of the capacitor 2 is grounded;
a capacitor C3 is connected in parallel with two ends of the capacitor C2, and a capacitor C4 is connected in parallel with two ends of the capacitor C3;
the other end of the inductor L2 is connected with one end of the capacitor C5;
the other end of the capacitor C5 is grounded;
the inductor L3 is connected with the inductor L2 in parallel;
one end of the capacitor C5 is also connected with one end of the resistor R2, and the other end of the resistor R2 is connected with the power supply 2;
the resistor R3 is connected with the resistor R2 in parallel;
the functional module is connected to the power supply 2.
Optionally, the functional module includes: the display device comprises a signal processing chip and a display module;
the power end of the functional module is connected with the power supply 2;
the signal processing chip comprises an HDMI interface and an LVDS interface;
the signal processing chip is used for receiving the HDMI signals through the HDMI interface, converting the HDMI signals into LVDS signals and outputting the LVDS signals to the display module through the LVDS interface for output and display.
Optionally, the MOS transistors Q1 and Q2 are both N-MOS transistors.
The noise reduction method eliminates the noise generated by the vibration of the electronic element, thereby improving the noise environment of the electronic system of products such as wearable products and the like.
Drawings
FIG. 1 is a schematic diagram of placement of components on a prior art electronic system PCB;
FIG. 2 is a circuit diagram of a voltage conversion circuit in a prior art electronic system;
FIG. 3 is a flow chart of a method of reducing noise in an electronic system according to an embodiment of the invention;
FIG. 4 is a flow chart of a method of reducing noise in an electronic system according to an embodiment of the invention;
FIG. 5 is a schematic diagram of placement of components on an electronic system PCB according to one embodiment of the invention;
FIG. 6 is a circuit diagram of a voltage conversion circuit according to an embodiment of the present invention;
fig. 7 is a circuit diagram of a voltage conversion circuit according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The core idea of the invention is to use the noise vibration principle to firstly determine the elements emitting noise, generally passive elements such as resistance, capacitance, inductance, etc., aiming at the problem that the electronic elements of the existing electronic system generate noise due to vibration. Then, these noise-generating components are replaced with two equivalent identical components, and are symmetrically disposed on both sides of a printed circuit Board (printedcuit Board) PCB, respectively. Thus, due to the coincidence of the frequencies of the two equivalent elements, the direction of the element vibration is also coincident. When placed on both sides of the PCB, the vibration directions of the two equivalent elements are exactly opposite, cancelling out the amplitudes. Therefore, the purpose of eliminating noise generated by two equivalent elements is achieved, and the comfort and the practicability of the whole electronic system are improved.
Fig. 3 is a flow chart of a noise reduction method of an electronic system according to an embodiment of the present invention, and referring to fig. 3, the noise reduction method of the present invention includes:
step S310, searching elements generating noise on a PCB of the electronic system;
step S320, for each searched component generating noise, replacing the component with a first component and a second component which are connected in parallel and have the same value, wherein the first component and the second component are the same as the component and are equivalent to the component after being connected in parallel;
step S330, the first element and the second element are placed on the two sides of the PCB in the same direction, so that the noise generated by the first element and the second element is mutually offset.
Through the steps, the noises generated by the two equivalent electronic components can be mutually offset, so that the purpose of reducing the noise of the electronic system is achieved, and the noise reduction method is simple and easy to implement and low in cost.
In an embodiment of the present invention, after step S330, step S340 is further included: noise of the electronic system is detected and determined to be satisfactory.
Referring to fig. 4, the specific working flow of the noise reduction method of the present invention is to first determine whether the electronic noise generated by the electronic system is too large, which affects the normal use and comfort of people, according to the determination criteria. Secondly, after the electronic system is judged to be over-noisy, the noise emitted by one or more elements at the position is checked by a noise checking tool. And thirdly, replacing the noise source element with two equivalent and parallel elements, namely, the requirement of replacing needs to be met that the two equivalent elements are equivalent to the elements before replacement after being connected in parallel, and symmetrically placing the two equivalent elements on two sides of the PCB. In this way, due to the coincidence of the vibration frequencies and amplitudes of the two elements, but in opposite directions, the vibration noise can be cancelled out. And finally, judging that the noise meets the standard.
The noise reduction method mainly aims at electronic noise generated by electronic elements, in an electronic system, vibration noise generated by passive elements is sometimes extremely large, particularly on wearable products such as head-mounted electronic equipment or wristbands, the noise is more obvious, and users can hear the noise, so that the comfort and the practicability of the products are seriously influenced. The noise reduction method can eliminate the vibration noise of the electronic element, thereby improving the comfort and the practicability of the electronic system in use. The specific noise reduction meets the standard, and the user experience can be judged through the judgment mode. Due to the noise caused by the vibration of elements in the electronic system, a user can hear the noise seriously, and after the noise is reduced by the method, the user can not hear or feel the noise, namely the noise is considered to reach the noise reduction standard.
Fig. 5 is a schematic diagram of placing components on an electronic system PCB according to an embodiment of the present invention, and referring to fig. 5, in this embodiment, a layout manner of electronic components on the PCB when noise reduction is performed by using the method of the present invention is described by taking a resistor R1, a capacitor C1, and an inductor L1 as noise source components as examples.
As shown in fig. 5, the resistor R1 generating noise is replaced by equivalent resistors R2 and R3, and R2 and R3 are equivalent to R1 after being connected in parallel; the capacitance C1 which generates noise is replaced by equivalent capacitances C2 and C3, and the equivalent of C2 and C3 is equivalent to C1 after being connected in parallel; the inductance L1 generating noise is replaced by equivalent inductance L2 and L3, and L2 and L3 are equivalent to L1 after being connected in parallel.
The replacement isovalent components are then placed on both sides of the PCB board in the layout of fig. 5 so that the noise generated by two isovalent components of the same type cancel each other out. When laying out components on a PCB, the following points need to be noted: first, equivalent replacement components are placed on the two sides of the PCB in those empty locations where there are no traces or components. Secondly, considering the requirements of cutting the PCB and the like, the placement of the replaced equivalent elements has a certain safe distance with the peripheral routing of the PCB, generally more than 20 mils. Thirdly, connecting the first element and the second element by a through hole, wherein the distance from the through hole to the two ends of each element is shortest; signal convergence between two isoelectronic components requires the opening of vias which are as close as possible to the pads of the components, keeping the distance to the components to a minimum, to eliminate crosstalk caused by the separation of the signal lines of the two isoelectronic components. Fourthly, the two equivalent elements are completely and symmetrically arranged, so that the direction of the flowing signals is ensured to be consistent, and the aim of eliminating the vibration noise to the maximum is fulfilled.
According to the layout mode of fig. 5, after the equivalent element replacement and layout are completed, the vibration noise of the electronic system is tested, so that the judgment that the equivalent element replacement and layout meet the standard can be made, and discomfort can not be brought to a user.
In one embodiment of the present invention, when replacing the equivalent component, the formula for replacing the capacitor is different according to different replacement formulas of the electronic component, and the formula for replacing the capacitor is as follows: c2 ═ C3 ═ C1 ═ 1/2; the formula for replacing the resistance is as follows: r2 ═ R3 ═ 2 × R1; the formula for replacing the inductor is as follows: L2-L3-2-L1.
In other embodiments of the invention, the values of the substituted equivalent elements should be calculated based on different characteristics of the different elements. In one embodiment of the present invention, the resistor R1, the inductor L1, and the capacitor C1 are all used as noise sources, but in other embodiments of the present invention, the noise sources may be any one or two of the three. Of course, the types of the electronic components are not limited to resistors, inductors and capacitors, and may be other passive components that generate electronic noise.
Fig. 6 is a circuit diagram of a voltage converting circuit according to an embodiment of the present invention, which takes a power supply circuit of a functional module in an electronic system of a head-mounted product as an example to specifically illustrate the application of the noise reduction method according to the present invention. In the electronic system (see fig. 2) in the prior art, the switching power supply circuit realizes voltage conversion by high-frequency switching, but voltage ripples are formed at the same time of switching, which causes the capacitor C1, the inductor L1 and the resistor R1 to stabilize the frequency vibration, and generates vibration noise.
Referring to fig. 6, the voltage conversion circuit to which the noise reduction method of the present invention is applied includes: the power supply comprises a power supply management chip, MOS (metal oxide semiconductor) tubes Q1 and Q2, a power supply 1, a power supply 2, inductors L2 and L3, capacitors C2, C3, C4 and C5, resistors R2 and R3 and a functional module; a high-level pin of the power management chip is connected with a grid electrode of the MOS tube Q1; the drain electrode of the MOS tube Q1 is connected with a power supply 1; the source electrode of the MOS tube Q1 is respectively connected with the switching pin of the power management chip, one end of the inductor L2 and the drain electrode of the MOS tube Q2; the grid electrode of the MOS tube Q2 is connected with a low level pin of the power management chip, and the source electrode of the MOS tube Q2 is grounded; one end of the capacitor C2 is connected with the power supply 1, and the other end of the capacitor 2 is grounded; a capacitor C3 is connected in parallel with two ends of the capacitor C2, and a capacitor C4 is connected in parallel with two ends of the capacitor C3; the other end of the inductor L2 is connected with one end of the capacitor C5; the other end of the capacitor C5 is grounded; the inductor L3 is connected with the inductor L2 in parallel; one end of the capacitor C5 is also connected with one end of the resistor R2, and the other end of the resistor R2 is connected with the power supply 2; the resistor R3 is connected with the resistor R2 in parallel; the functional module is connected to the power supply 2.
Referring to fig. 6, in a circuit implementing a voltage conversion function using a switching power supply circuit, U1 is a switching power supply management chip that converts the high voltage of power supply 1 to a low voltage of power supply 2 suitable for use by the functional module. The conversion principle is to control a reasonable output duty ratio, and the conversion of the voltage is realized by alternately turning on and off Q1 and Q2 through a high level pin, a low level pin and a pin output of U1. Q1, Q2 is N-MOS tube as switching element; c1 and C4 are input capacitors and are used for removing circuit coupling and stabilizing voltage; l1 is an energy storage element inductor, which realizes the voltage reduction function. The capacitor C5 is used for removing circuit coupling and stabilizing voltage; resistor R1 acts as a current limiting.
As shown in fig. 6, each noise-generating element, namely, the capacitor C1, the inductor L1 and the resistor R1, is replaced by two equivalent elements of the same type, and each two equivalent elements are arranged on two sides of the PCB in parallel, so that the vibration noise generated by the two elements is cancelled, the discomfort caused by the vibration noise of the electronic element when the user uses the electronic element is eliminated, and the comfort and the practicability of wearable electronic products such as a head-worn or wrist strap are improved.
Fig. 7 is a circuit diagram of a voltage conversion circuit according to an embodiment of the present invention, and referring to fig. 7, the functional block in fig. 6 includes: the signal processing chip is used for converting a high-definition multimedia interface (HDMI) signal into a low-voltage differential signal (LVDS) and outputting the LVDS to a display module (a Liquid Crystal Display (LCD)), so that the display module performs a screen display function.
Fig. 7 shows the working mode of applying the noise reduction method of the present invention to realize the voltage conversion function and eliminate the noise caused by the vibration of the components in the circuit during the voltage conversion: the slave power switching Chip U1 controls to convert the high voltage of the power supply 1 into a voltage suitable for power in U2, the U1 includes a Chip set (System on Chip, SoC for short), and the function of the SoC Chip set is to process and convert the input HDMI signals into LVDS signals so as to adapt to the LCD screen display of the liquid crystal display. The power supply 2 is connected to a powerpin pin of the U2 to supply power to the U2, an external HDMI signal is input to an HDMI interface of the U2, and the processed and converted signal is output to the LCD through an LVDS interface of the U2.
The method of the invention is used for noise reduction, so that the LCD is not influenced by the vibration noise of electronic elements when in output display, and a user does not have uncomfortable feeling caused by the electronic noise when using the LCD.
In addition, the invention also provides an electronic system, which comprises a plurality of elements arranged on the PCB, wherein each element generating noise is replaced by a first element and a second element which are connected in parallel and have equal values; the first element and the second element are the same as the element and are equivalent to the element after being connected in parallel; the first element and the second element are symmetrically placed on both sides of the PCB. The vibration noise of the elements in the electronic system can be mutually offset, and the comfort and the user experience of the electronic system product are improved.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (3)
1. A method of noise reduction for an electronic system, the method comprising:
step S310, searching and determining elements generating noise on a PCB of the electronic system;
step S320, for each searched component generating noise, replacing the component at a blank position without wires or components on two surfaces of the PCB with a first component and a second component which are connected in parallel and have the same value, wherein the first component and the second component are the same as the component and are equivalent to the component after being connected in parallel;
step S330, symmetrically placing the first element and the second element on two sides of the PCB to enable the noise generated by the first element and the second element to be mutually offset;
the symmetrically placing the first and second elements on both sides of the PCB board comprises: connecting the first element and the second element by a through hole, wherein the through hole respectively has the shortest distance to two ends of the first element and the second element; the equivalent first element and the equivalent second element are placed in the same direction, so that the direction of the flow signals is ensured to be the same; signal convergence between two equivalent elements requires the punching of vias.
2. The noise reduction method according to claim 1, wherein the step S330 is followed by the step S340: noise of the electronic system is detected and determined to be satisfactory.
3. The method of reducing noise according to claim 1, wherein the noise-producing noise elements comprise one or more of: a resistance; a capacitor; an inductance.
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| CN201410384460.9A CN104201865B (en) | 2014-08-06 | 2014-08-06 | Electronic system and noise reduction method thereof and voltage switching circuit |
| CN201611140915.8A CN106787623B (en) | 2014-08-06 | 2014-08-06 | Noise reduction method of electronic system, electronic system and voltage conversion circuit |
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| JP2014036138A (en) * | 2012-08-09 | 2014-02-24 | Mitsubishi Electric Corp | Printed circuit board |
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| US6417462B1 (en) * | 2000-06-19 | 2002-07-09 | Intel Corporation | Low cost and high speed 3-load printed wiring board bus topology |
| TW200944076A (en) * | 2008-04-07 | 2009-10-16 | Phoenix Prec Technology Corp | Printed circuit board and manufacturing method thereof |
| CN101364770A (en) * | 2008-10-08 | 2009-02-11 | 复旦大学 | A Monolithically Integrated High Frequency Step-Down DC-DC Converter |
| CN201345758Y (en) * | 2008-12-22 | 2009-11-11 | 北京风光动力科技有限公司 | LED high-efficiency time-delay power control constant-current module |
| CN201887821U (en) * | 2010-10-28 | 2011-06-29 | 广东欧珀移动通信有限公司 | A PCB routing circuit for suppressing mobile phone TDD noise |
| CN102956219B (en) * | 2012-11-19 | 2015-04-01 | 天津三星电子有限公司 | Display terminal |
| CN103872905A (en) * | 2012-12-14 | 2014-06-18 | 鸿富锦精密工业（深圳）有限公司 | Power supply control device |
| CN203673582U (en) * | 2014-01-06 | 2014-06-25 | 青岛海信智能商用系统有限公司 | Double screen display interface circuit and POS machine |
| CN204131369U (en) * | 2014-08-06 | 2015-01-28 | 青岛歌尔声学科技有限公司 | A kind of electronic system and voltage conversion circuit |
| CN106787623B (en) * | 2014-08-06 | 2020-06-26 | 歌尔科技有限公司 | Noise reduction method of electronic system, electronic system and voltage conversion circuit |
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| JP2014036138A (en) * | 2012-08-09 | 2014-02-24 | Mitsubishi Electric Corp | Printed circuit board |
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