CN206472115U

CN206472115U - Without spread spectrum clock signal EMI suppression circuits

Info

Publication number: CN206472115U
Application number: CN201621135173.5U
Authority: CN
Inventors: 李天强; 岳钢; 王泽龙; 韩雁斌; 朱天朋
Original assignee: Yanfeng Visteon Electronic Technology Shanghai Co Ltd
Current assignee: Yanfeng Visteon Electronic Technology Shanghai Co Ltd
Priority date: 2016-10-19
Filing date: 2016-10-19
Publication date: 2017-09-05
Anticipated expiration: 2026-10-19

Abstract

One kind is related to technical field of automotive electronics without spread spectrum clock signal EMI suppression circuits, and what is solved is the technical problem for suppressing clock signal EMI.The circuit includes magnetic bead, first resistor device, the first inductor, the first capacitor, the second capacitor, the 3rd capacitor, the first clamp diode, the second clamp diode, and at least one signal source of clock；The output end of each signal source of clock is connected to the input of first resistor device by magnetic bead, the output of first resistor device terminates the first capacitor to ground, and the output of first resistor device terminates the first clamp diode to ground, and the output of first resistor device terminates the second capacitor to ground；The output end of the input termination first resistor device of first inductor, the output of the first inductor terminates the 3rd capacitor to ground, and the output of the first inductor terminates the second clamp diode to ground.The utility model provide circuit, be particularly suitable for use in can not spread spectrum clock signal.

Description

Without spread spectrum clock signal EMI suppression circuits

Technical field

The utility model is related to electricity field, more particularly to automotive electronic technology, and particularly one kind is without spread spectrum clock signal EMI suppression circuits.

Background technology

For the EMI of clock signal（Electromagnetic interference）Restrain measurement mainly has ground connection, shielding, filtering and several tradition of spread spectrum Method, but under automotive electronics increasingly complex environment, this several conventional method has following defect：

1）EMI is suppressed using earthing method：Because vehicle electronics volume is smaller, it is easy between each functional module There is crosstalk phenomenon, when the frequency of clock signal is fallen into the operating frequency range of other modules, pressed down using earthing method EMI processed can reduce the stability of other modules work.

2）EMI is suppressed using metallic shield：This method is merely able to reduce the interference that correlation module gives off, for By the clock signal of PCB trace, this method can not be reduced by transmitting EMI problems caused by beta radiation.

3）EMI is suppressed using filtering method：It is simple to reduce the amplitude and phase of clock signal waveform, meeting using filtering Influence the job stability of circuit.

4）EMI is suppressed 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, is radiated for the energy that reduces clock signal and its harmonic wave, but can only to reduce specific frequency attached for the technology Near energy radiation, for good reduction can not be realized in the frequency signal without spread spectrum function and wider frequency domain Energy is radiated.

Utility model content

For defect present in above-mentioned prior art, technical problem to be solved in the utility model is to provide a kind of energy Effectively suppress the EMI of clock signal, and without spread spectrum without spread spectrum clock signal EMI suppression circuits.

It is in order to solve the above-mentioned technical problem, provided by the utility model a kind of without spread spectrum clock signal EMI suppression circuits, It is characterized in that：Including magnetic bead, first resistor device, the first inductor, the first capacitor, the second capacitor, the 3rd capacitor, One clamp diode, the second clamp diode, and at least one signal source of clock；

The output end of each signal source of clock is connected to the input of first resistor device, the output of first resistor device by magnetic bead The first capacitor is terminated to ground, and first resistor device output terminate the first clamp diode to, and first resistor device Output terminate the second capacitor to；

The output end of the input termination first resistor device of first inductor, the electricity of output termination the 3rd of the first inductor Container is to ground, and the output of the first inductor terminates the second clamp diode to ground.

The utility model provide without spread spectrum clock signal EMI suppression circuits, High-frequency Interference is absorbed using magnetic bead, utilize Resistance reduces the radiation of higher frequency signal energy externally with the frequency low pass ripple of electric capacity composition, is prevented using clamp diode The interference of electrostatic surge pulse, and shaping is carried out using pi type filter, can be to clock phase offset correction, raising front end drop Low clock amplitude, can also filter out the CLK higher hamonic wave signals that processor chips are reflected, can effectively suppress clock signal EMI, and clock signal reduces the radiation of overall frequency domain without spread spectrum, at the same do not influence again clock signal phase and Amplitude, and circuit cost is relatively low, while having good inhibition to EMC radiation etc. again, simultaneously in automotive electronics The radio part beat noise reductions in portion have good inhibition.

Brief description of the drawings

Fig. 1 is the circuit diagram without spread spectrum clock signal EMI suppression circuits of the utility model embodiment.

Embodiment

Below in conjunction with brief description of the drawings embodiment of the present utility model is described in further detail, but the present embodiment and without It is every to use similar structure of the present utility model and its similar change in limitation the utility model, the utility model all should be included in Protection domain, the pause mark in the utility model represents the relation of sum.

As shown in figure 1, one kind that the utility model embodiment is provided is without spread spectrum clock signal EMI suppression circuits, it is special Levy and be：Including magnetic bead ATTN1, first resistor device R1, the first inductor L1, the first capacitor C1, the second capacitor C2, the 3rd Capacitor C3, the first clamp diode D1, the second clamp diode D2, and at least one signal source of clock CLOCK；

Each signal source of clock CLOCK output end is connected to first resistor device R1 input, first by magnetic bead ATTN1 Resistor R1 output terminates the first capacitor C1 to ground, and first resistor device R1 output terminates the first clamp diode D1 Output to ground, and first resistor device R1 terminates the second capacitor C2 to ground；

The input termination first resistor device R1 of first inductor L1 output end, the first inductor L1 output termination 3rd capacitor C3 is to ground, and the first inductor L1 output terminates the second clamp diode D2 to ground.

The operation principle of the utility model embodiment is as follows：

The clock signal of signal source of clock CLOCK output sequentially passes through magnetic bead ATTN1, first resistor device R1, magnetic bead pair High-frequency Interference has absorption, can not only prevent because resonance causes other EMI problems, and can prevent high frequency from believing Number it is radiate in clock signal output terminal by PCB, so as to avoid high frequency E MI exceeded；First resistor device R1 is used to drop The amplitude of low-clock signal, can so effectively reduce the radiation of fundamental frequency energy externally；First resistor device R1 and the first electric capacity Device C1 constitutes frequency low pass wave mode, further the radiation of reduction higher frequency signal energy externally；First clamp diode D1 is used for Clamp signal amplitude voltage, is allowed to control within the specific limits；Second clamp diode D2 is used for clamp signal amplitude voltage, makes Control in certain limit, while preventing electrostatic surge pulse from disturbing signal input part；Due to after first resistor device The amplitude of clock signal can be reduced, although performance requirement can be met at normal temperatures, but in order to ensure electronic product is severe High and low temperature environment under can also be for a long time normal work, it is necessary to use pi type filter in processor chips input Carry out shaping；Second capacitor C2, the first inductor L1, the 3rd capacitor C3 constitute pi type filter, and pi type filter is on the one hand Processing on the other hand can also be filtered out for realizing to clock phase offset correction, improving the clock amplitude that front end is reduced The CLK higher hamonic wave signals that device chip is reflected, prevent these high-frequency energies from influenceing the EMI performances of complete machine by space radiation.

The utility model embodiment be particularly suitable for use in can not spread spectrum clock signal, the spoke of overall frequency domain can be reduced Penetrate, while not influenceing the phase and overall amplitude of clock signal again, circuit function and performance are preferably balanced.

Sine wave, square wave frequency of the utility model embodiment for 108MHz, fundamental frequency 108MHz and its frequency multiplication 108MHz* N（N is odd number）, half frequency multiplication 54MHz and its strange frequency multiplication 54MHz*N（N is odd number）, 27MHz and strange frequency multiplication 27MHz*N（N is strange Number）, 13.5MHz and its strange frequency multiplication 13.5MHz*N（N is odd number）Radiation at these frequencies has good inhibition, right There is good inhibition in internal radio part 94.5MHz, 108MHz beat noise.

Sine wave, square wave frequency of the utility model embodiment for 54MHz, fundamental frequency 54MHz and its frequency multiplication 54MHz*N（N For integer）, half frequency multiplication 27MHz and its frequency multiplication 27MHz*N（N is integer）, 13.5MHz and its frequency multiplication 13.5MHz*N（N is integer） Radiation at these frequencies has good inhibition, for internal radio part 94.5MHz, 108MHz beat Noise has good inhibition.

Claims

1. one kind is without spread spectrum clock signal EMI suppression circuits, it is characterised in that：Including magnetic bead, first resistor device, the first inductance Device, the first capacitor, the second capacitor, the 3rd capacitor, the first clamp diode, the second clamp diode, and at least one Signal source of clock；

The output end of each signal source of clock is connected to the input of first resistor device, the output termination of first resistor device by magnetic bead First capacitor to ground, and first resistor device output terminate the first clamp diode to, and first resistor device is defeated Go out the second capacitor of termination to ground；

The output end of the input termination first resistor device of first inductor, the output of the first inductor terminates the 3rd capacitor Output to ground, and the first inductor terminates the second clamp diode to ground.