RF Circuit Design, 2nd Edition

Chapter 7: Grounding

7.1 Implication of Grounding

Grounding is a common concern in all circuit design for circuit blocks and systems, including RF, digital, and analog circuit designs. As long as the circuit operates in AC mode, grounding must be done properly no matter how low or high the operating frequencies are. In the RF frequency range, grounding becomes a more serious matter because RF frequencies are usually higher than other AC frequencies. Many problems or “bugs” arise from inappropriate grounding. As a matter of fact, grounding is one of the core technologies and an indispensable skill in RF circuit design. In high-speed digital circuit designs, grounding is as important as in RF circuit design.

In a circuit block or a system, there are many ground points or nodes marked in a schematic. Figure 7.1 shows a typical way to draw a schematic of circuitry, in which the positive terminal of the DC power supply point is marked with V_cc and the negative terminal of the DC power supply is marked with GND or by an up-side-down symbol “Δ.” The positive terminal of the DC power supply point, V_cc, is connected to many subpoints of DC power supply, V_cc1 to V_cc8, and the negative terminal of the DC power supply point, GND, is connected to many subpoints of ground points, G₁ to G₈.

Figure 7.1 A typical way to draw a schematic of circuitry.

First, a question is raised: which grounded ...