CN207853862U - The EMI suppression circuits of square-like clock signal higher hamonic wave - Google Patents
The EMI suppression circuits of square-like clock signal higher hamonic wave Download PDFInfo
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- CN207853862U CN207853862U CN201820171638.5U CN201820171638U CN207853862U CN 207853862 U CN207853862 U CN 207853862U CN 201820171638 U CN201820171638 U CN 201820171638U CN 207853862 U CN207853862 U CN 207853862U
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- clock signal
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Abstract
A kind of EMI suppression circuits of square-like clock signal higher hamonic wave, including resistor, the first capacitor, the second capacitor, the load of clock signal input terminal mouth and square-like clock signal source, wherein, the output end in the square-like clock signal source connects ground terminal by resistor and the first capacitor, second capacitor is in parallel with resistor and the first capacitor, and the resistor, the first capacitor and the second capacitor are loaded close to clock signal input terminal mouth and placed.The utility model can ensure signal integrity demand when square wave signal transmission, effectively inhibit the appearance of signal rising edge and failing edge ring.The energy of square-wave signal higher hamonic wave can be effectively reduced for the adjustment of rising edge and failing edge time, the failure risk of EMI is reduced in signal source end, it does not influence the phase and amplitude of square-like clock signal again simultaneously, and circuit cost is relatively low, and has good inhibition to EMC radiation etc..
Description
Technical field
The utility model is related to electricity field more particularly to electrical automotive circuits, especially a kind of square-like clock signal is high
The EMI suppression circuits of subharmonic.
Background technology
In the prior art, for the EMI of clock signal（Electromagnetic interference）Restrain measurement mainly have ground connection, shielding, filtering and
Spread spectrum, but under automotive electronics increasingly complex environment, these types of conventional method has following defect：
1）EMI is inhibited using earthing method：Due to the rising edge and failing edge steeper of square-like clock signal, so
The spectral range that the higher hamonic wave energy of square-wave signal is very high and covering is extremely wide, high-frequency harmonic signal can be by PCB
In very short signal wire and ground wire as in aerial radiation to space, square-like clock signal is simply inhibited using earthing method
Higher hamonic wave be not obvious in high frequency section effect.
2）EMI is inhibited using metallic shield：This method is merely able to reduce the interference that correlation module gives off, still
Higher hamonic wave signal can be radiated by PCB trace in space, and this method can not be reduced through EMI radiation caused by transmission line
Problem.
3）EMI is inhibited using filtering method：The simple amplitude and phase that clock signal waveform can be reduced using RC filtering,
The minor change of filter condenser, which may result in square-wave signal, larger distortion.
4）EMI is inhibited using spread spectrum method：This method is to various clock signals using the technology of spread spectrum to specific frequency
Rate carries out spread-spectrum processing, and for reducing the energy radiation of clock signal and its harmonic wave, but the technology is only used for spread spectrum work(
The clock signal output terminal of energy, and the radiation of the energy near specific frequency can only be reduced, for the frequency of no spread spectrum function
Drop low-energy radiation cannot be realized in signal and wider frequency domain well.
Utility model content
It is described the purpose of this utility model is to provide a kind of EMI suppression circuits of square-like clock signal higher hamonic wave
The EMI suppression circuits of this square-like clock signal higher hamonic wave will solve earthing method in the prior art and higher hamonic wave is inhibited to exist
High frequency section effect unobvious, EMI methods can not reduce radiation, filtering method causes square-wave signal larger for metallic shield inhibition
The technology that distortion, spread spectrum method need clock signal output terminal to support that spread spectrum function and reduction energy radiation scope are limited is asked
Topic.
The EMI suppression circuits of this square-like clock signal higher hamonic wave of the utility model, including resistor, the first capacitance
Device, the second capacitor, the load of clock signal input terminal mouth and square-like clock signal source, wherein the square-like clock signal source
Output end ground terminal is connected by resistor and the first capacitor, second capacitor and resistor and the first capacitor are simultaneously
Connection, the resistor, the first capacitor and the second capacitor are connected with the load of clock signal input terminal mouth and close to placements.
Further, square-like clock signal source is more than one.
The utility model compares with prior art, and effect is positive and apparent.This square wave of the utility model
The output end of the EMI suppression circuits of clock signal higher hamonic wave, each square-like clock signal source passes through resistor and the first capacitance
For device to ground, the second capacitor is in parallel with resistor and the first capacitor.
The utility model carries out signal transmission matching using resistor and the first capacitor, utilizes the second capacitor progress side
The adjustment of wave signal rising edge and failing edge, it is ensured that signal integrity demand when square-wave signal transmits effectively inhibits letter
The appearance of number rising edge and failing edge ring.Adjustment for rising edge and failing edge time can effectively reduce square-wave signal height
The energy of subharmonic reduces the failure risk of EMI in signal source end, while not influencing the phase and width of square-like clock signal again
Degree, and circuit cost is relatively low, while having good inhibition to EMC radiation etc. again.
Description of the drawings
Fig. 1 is the schematic diagram of the EMI suppression circuits of the square-like clock signal higher hamonic wave of the utility model.
Fig. 2 is that clock signal when square-like clock signal does not carry out Proper Match in the prior art exports schematic diagram.
Fig. 3 is the clock signal output signal of the EMI suppression circuits of the square-like clock signal higher hamonic wave of the utility model
Figure.
Fig. 4 is the signal spectrum figure that square-like clock signal does not carry out higher hamonic wave when Proper Match in the prior art
Fig. 5 is the letter after the EMI suppression circuits of the square-like clock signal higher hamonic wave of the utility model are adjusted by signal
Number spectrogram.
Specific implementation mode
Embodiment 1
As shown in Figure 1, the EMI suppression circuits of this square-like clock signal higher hamonic wave of the utility model, including resistance
Device R1, the first capacitor C1, the second capacitor C2, clock signal input terminal mouth load U1 and square-like clock signal source V1, wherein
The output end of the square-like clock signal source V1 passes through resistor R1 and the first capacitor C1 connection ground terminals, the described second electricity
Container C2 is in parallel with resistor R1 and the first capacitor C1, the resistor R1, the first capacitor C1 and the second capacitor C2
It is connected and close to placement with clock signal input terminal mouth load U1.
Further, square-like clock signal source V1 is more than one.
As shown in Fig. 2, the appearance of clock signal low and high level position is bright when square-like clock signal does not carry out Proper Match
Aobvious oscillation, the rising edge and failing edge steeper of signal, the long distance transmission of the signal can cause higher hamonic wave to be coupling in
On signal wire around cabling, cause EMI exceeded.
As shown in figure 3, when the output square-like clock signal to square wave signal source of clock V1 is electric by resistor R1 and first
When container C1 is terminated, the signal after being terminated can not only ensure the demand of signal integrity, and reduce square wave
The ring situation of signal.The another advantage terminated using terminal can be directly walked in internal layer by MCU in PCB trace
Line, such cabling mode on the one hand can by the shielding on upper and lower stratum come reduce high-frequency signal surface layer cabling radiation wind
Danger, avoids high frequency E MI exceeded；On the other hand number of vias when signal lead can be reduced, the transmission quality of signal is improved.It is logical
The high level of square-like clock signal can be adjusted by crossing the first capacitor, it can be ensured that clock signal can meet load end pair always
In the demand of high level.Second capacitor is used to adjust the conversion time of the rising edge and failing edge of square-wave signal, is appropriately extended
The rising edge of square-wave signal and the conversion time of failing edge can greatly reduce the energy of higher hamonic wave.Such as Fig. 4 and Fig. 5 institutes
Show, adjusted by signal, the square-like clock signal after adjustment is in the band limits of 900MHz -1000MHz, spectrum energy drop
Low 30dB, the reduction of spectrum energy are greatly reduced the EMI failure risks of the square-like clock signal higher hamonic wave.
Square-like clock signal of the utility model especially suitable for long distance transmission, can reduce the radiation of high frequency frequency domain
Energy, while not influencing the phase of clock signal and whole amplitude again, circuit function and performance are preferably balanced.
Claims (2)
1. a kind of EMI suppression circuits of square-like clock signal higher hamonic wave, including resistor, the first capacitor, the second capacitor,
Clock signal input terminal mouth loads and square-like clock signal source, which is characterized in that the output end in the square-like clock signal source
Ground terminal is connected by resistor and the first capacitor, second capacitor is in parallel with resistor and the first capacitor, described
The load of resistor, the first capacitor and the second capacitor and clock signal input terminal mouth be connected and close to placement.
2. the EMI suppression circuits of square-like clock signal higher hamonic wave as described in claim 1, it is characterised in that：The square wave
Signal source of clock is more than one.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201820171638.5U CN207853862U (en) | 2018-02-01 | 2018-02-01 | The EMI suppression circuits of square-like clock signal higher hamonic wave |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201820171638.5U CN207853862U (en) | 2018-02-01 | 2018-02-01 | The EMI suppression circuits of square-like clock signal higher hamonic wave |
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| CN207853862U true CN207853862U (en) | 2018-09-11 |
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| CN201820171638.5U Active CN207853862U (en) | 2018-02-01 | 2018-02-01 | The EMI suppression circuits of square-like clock signal higher hamonic wave |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108063640A (en) * | 2017-11-13 | 2018-05-22 | 广东欧珀移动通信有限公司 | Method and system, device and the computer readable storage medium of anti-MIPI buses interference |
-
2018
- 2018-02-01 CN CN201820171638.5U patent/CN207853862U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108063640A (en) * | 2017-11-13 | 2018-05-22 | 广东欧珀移动通信有限公司 | Method and system, device and the computer readable storage medium of anti-MIPI buses interference |
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