1. Multilayer board wiring: High-frequency circuits frequently have a high integration and wiring density. Multilayer boards are not only required for wiring, but they are also an excellent way to prevent interference. A reasonable selection of the size of a certain number of layers of printed board during the PCB layout stage can make full use of the middle layer to set the shielding, better realize the nearby grounding, effectively reduce the parasitic inductance and shorten the signal transmission length, and greatly reduce signal cross interference. All of these strategies improve the reliability of high-frequency circuits.
2. Avoid routing loops: Try not to generate a loop when routing multiple high-frequency signals. Make the loop region as minimal as possible if it is unavoidable.
3. The less bending in the lead, the better: the lead of a high-frequency circuit wiring is ideal to use a full straight line, which requires turning, and a 45 degree broken line or arc turning can be employed. This criterion is only utilized to improve the fixing strength of copper foil in low-frequency circuits, although achieving this need can reduce external emission and mutual coupling of high-frequency signals in high-frequency circuits.

PCB design rules for high frequency

1. The less lead interlayer alternation, the better: The phrase “the less the interlayer alternation of leads, the better” refers to the number of vias (vias) employed in the component connecting procedure. One through can bring roughly 0.5pf dispersed capacitance, according to measurements. Reducing the number of vias can enhance performance and lessen the chance of data errors.

1. The shorter the lead, the better: signal radiation intensity is proportional to signal line length. The greater the length of the high-frequency signal lead, the easier it is to couple to the components nearby. As a result, the shorter the lead, the better for high-frequency signal lines such as signal clock, crystal oscillator, DDR data, LVDS line, USB line, HDMI line, and so on.
2. The ground wire of a high-frequency digital signal must be isolated from the ground wire of an analog signal: when the analog and digital ground wires are connected to the public ground wire, they must be connected with high-frequency choke beads or directly isolated, and a suitable location for single point interconnection must be chosen. The ground potential of a high-frequency digital signal’s ground wire is often inconsistent, and there is frequently a voltage differential between the two. Furthermore, the high-frequency digital transmission’s ground cable frequently carries a highly rich harmonic component of the high-frequency signal. When the ground wires of the digital signal and the analog signal are directly coupled, the harmonic of the high-frequency signal will interfere with the analog signal via ground wire coupling. As a result, in general, the ground wires of high-frequency digital and analog signals must be isolated, which can be accomplished by connecting a single point at a suitable position or by high-frequency choke beads.
3. Connect a high-frequency decoupling capacitor to the integrated circuit block’s power pin: Connect a high-frequency decoupling capacitor to the power pin of each integrated circuit block. Increasing the power pin’s high-frequency decoupling capacitance substantially suppresses interference generated by high-frequency harmonics.