The paper proposes a unified switch model for the analysis of circuits with ideal switches. The model is unique and valid for all states of switches. The developed model is based on modified nodal analysis (MNA) that exploits an efficient algorithm developed for linear active circuits. The analysis with the new switch model requires only one topology and uses the uniform system equations regardless of states of switches. The system equations and the states of switches are updated by control variables, used in the model. There are no restrictions on circuit topology and switch connections. The switches can be both externally and internally controlled. The inconsistent initial value problem and Dirac delta impulses occurring because of ideal switch are discussed in detail. Two examples are given concerning the analysis of circuits with ideal switch.