High frequency equivalent circuit diagram of resistor

Resistors are the most widely used components in PCBs. Commonly used resistors include carbon, wire-wound and film chip resistors. Wire-wound resistors are not suitable for high-speed and high-frequency circuit applications due to the excessive lead inductance. Thin film chip resistors are often used in circuits, but they also have hidden radio frequency characteristics. The figure shows the high-frequency equivalent circuit of a resistor with a nominal value R.

Figure high frequency equivalent circuit of resistor

As shown in the figure, L is the inductance of the two metal pins; the capacitor Ca is the parasitic capacitance inside the resistor; Cb is the parasitic capacitance between the two metal pins (negligible). The two most easily overlooked aspects of resistors are package size and internal parasitic capacitance. Different packages have different parasitic parameters. Generally speaking, smaller "SMD" packages have smaller parasitic parameters. For example, the 0603 package is more suitable for high-speed high-frequency circuits than the 1206 package.