Integrated package structure for generating low electromagnetic interference clock signal

Abstract

The invention relates to the field of electromagnetic interference suppression, and specifically relates to an integrated package structure for generating a low electromagnetic interference clock signal. The integrated package structure comprises a clock source module, a phase generator and a phase modulator, which are orderly connected with each other; the clock source module, the phase generator and the phase modulator are integrated in a standard and general package structure; the clock source module comprises a crystal and an oscillation circuit module; the phase generator generates modulation clock signals with a phase difference; and the phase modulator generates a spread spectrum clock signal. By designing the integrated package structure for generating the low electromagnetic interference clock signal, the clock source module, the phase generator and the phase modulator are integrated in the standard and general package structure, so that the suppression effect of a crystal oscillator clock EMI (Electro Magnetic Interference) can be improved and the integrity of signals can be kept; meanwhile, the integrated package structure is convenient for directly replacing a clock source without changing an original arrangement structure of the circuit, and convenient for replacement and improving the work efficiency.

Description

technical field [0001] The invention relates to the field of electromagnetic interference suppression, in particular to an integrated packaging structure for generating low electromagnetic interference clock signals. Background technique [0002] With the development of intelligent and high-speed electronic products, electromagnetic compatibility has become an important indicator for evaluating the quality of electronic products. According to the definition of electromagnetic compatibility by the International Electronics Commission standard IEC, it mainly includes two parts: EMI (electromagnetic emission) and EMS (electromagnetic immunity). Such as figure 1 As shown, the crystal oscillator circuit (active crystal oscillator) has always been used as the core functional device of electronic products to generate clock signals. It is directly connected to the MCU and is also the main source of EMI emissions. Therefore, the EMI suppression of the crystal oscillator clock is par...

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Problems solved by technology

[0003] Existing EMI suppression schemes for crystal oscillator clocks mainly include two traditional methods of shielding and filtering, but the above methods will have unsatisfactory suppression effects due to some external factors, specifically:

[0004] 1. Use a metal shield to shield the crystal oscillator circuit. Although the metal shield can suppress the emission of the crystal oscillator, due to the trend of miniaturization and integrated design of electronic products, and the intricate PCB wiring, crystal oscillator interference is easy to pass through the PCB. The crosstalk between emits

[0005] 2. Filtering the crystal oscillator circuit can reduce the output amplitude of the crystal oscillator clock and reduce EMI emissions, but the existence of the filter circuit will change the signal waveform of the crystal oscillator clock signal, such as the rising and falling edge times of the crystal oscillator clock signal, destroying the clock signal The signal integrity of the signal affects the stability of the system

[0006] Although the above-mentioned traditional rectification methods can reduce EMI emissions to a certain extent, because they do not suppress EMI at the source of the clock, it takes a lot of time to check the propagation path of crystal oscillator clock emissions, and a lot of time is spent in the EMI rectification process

[0007] In addition, if a circuit structure related to suppressing EMI is set between the crystal oscillator clock source and the MCU, although the EMI of the crystal oscillator clock can be suppressed at the source, the above-mentioned method will modify the originally designed circuit board structure, especially After the circuit board is manufactured, it is very difficult to suppress EMI through the above method, and it is not suitable for large-scale formed circuit boards.

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