DC Block

A DC block is a capacitor with an infinite capacitance. During DC simulation the DC block is an open circuit. Thus, its MNA entries are all zero.

The MNA matrix entries of a DC block correspond to an ideal short circuit during AC analysis which is modeled by a voltage source with zero voltage.

$$\begin{bmatrix}. & . & +1\\ . & . & -1\\ +1 & -1 & 0\\ \end{bmatr... ...in{bmatrix}I_1\\ I_2\\ 0 \end{bmatrix} = \begin{bmatrix}0\\ 0\\ 0 \end{bmatrix}$$ (9.17)

The scattering parameters writes as follows.

$$(S) = \begin{pmatrix}0 & 1\\ 1 & 0\\ \end{pmatrix}$$ (9.18)

A DC block is noise free. A model for transient simulation does not exist. It is common practice to model it as a capacitor with finite capacitance whose value is entered by the user.