High Frequency Circuit Design Tips

HF (High Frequency) circuit design is subject to very different physical rules than traditional DC or low frequency designs. In this world where even a path of a few millimeters creates an inductor effect, the following points should be considered for a successful PCB design:

Impedance Matching

To prevent signal reflections, the impedance between source, transmission line and load (usually 50 Ohm) must be fully compatible. Microstrip calculations are vital at this point.

Vias and Grounding

The ground plane in RF circuits must be continuous. The use of via (transition hole) should be kept to a minimum, and when used, protective ground stitches (vias stitching) should be placed around it.

Component Placement

Critical components should be placed as close to each other as possible, and high-gain sections and oscillator parts should be physically isolated. This placement pattern is key to passing Electromagnetic Compatibility (EMC) tests.