PCB News - Is the capacitor close to the chip or the crystal is close to the chip

In PCB design.Is the capacitor close to the chip or the crystal is close to the chip

Ask about the crystal oscillator. There is no requirement for the distance between the crystal oscillator and the CPU. How do you usually place the crystal oscillator, and does it have any special requirements for wiring?

Of course, the closer you are to the CPU, the better.

Do not run important signal lines under the crystal oscillator. It is a source of interference. The clock signal should be drilled as little as possible. The clock signal should not cross the dividing plane. These factors will cause impedance changes and affect signal quality. It is better to also cover the ground network copper skin for the crystal oscillator. . .

It is better for the crystal oscillator to be close to the cpu, because this can ensure the shortest trace (to be made into a differential line), and there should be no signal lines passing through the adjacent layer under the crystal oscillator. You should also be careful not to get too close to the edge of the PCB board.

The crystal oscillator (quartz crystal resonator) should be closer to the chip (for higher frequency accuracy requirements, the closer the better), because the distribution parameters of the circuit board will affect the frequency accuracy.
The resonant frequency of the oscillation circuit is closely related to the capacitance between the pins of the quartz crystal resonator (called the load capacitance of the crystal), and its change will directly cause the resonant frequency of the oscillation circuit to change.

The closer you are to the CPU, the better. It is also better to consider the process, whether there is interference between the devices, and whether it is convenient to solder. The inductance and capacitance of the crystal oscillator is as close as possible to its power supply pin. The trace should be as short and straight as possible, and no vias should appear. Finally, it can be handled in a three-dimensional package. In the case of crystals, pay attention to the placement of capacitors and the grounding of similar differential traces.

Of course, the shorter the wiring, the better.

Modular design. Capacitor and crystal oscillator are a module closer. As part of the MCU clock (crystal oscillator and capacitor module), the requirements should be stricter when designing. Try to determine the position at the beginning of the design, and to a certain extent Pay attention to shielding interference. The single-chip computer and the clock module should be closer. If they are far away, the clock is unstable and it is easy for the crystal oscillator to fail to oscillate. The above is the introduction of whether the capacitor is close to the chip or the crystal oscillator is close to the chip.