Boolean circuits which correspond to L/poly
$\mathsf{L}/\mathrm{poly}$ can be characterized by polynomial size skew circuits. A boolean circuit is called skew if every AND-gate has at most one child that is not an input gate. Skew circuits and branching programs can simulate each other with polynomial blow-up, so polynomial size skew circuits and branching programs compute the same class of functions, which is $\mathsf{L}/\mathrm{poly}$.

A proof of these simulations can e.g. be found in this paper by Balaji, Krebs and Limaye.