In this paper, we discuss the challenges in modelling of Noisy Intermediate Scale Quantum Computers, in particular, those implementations that rely on integrated interface and control electronics. We begin by overviewing the current state of quantum computers and highlight the emergence of quantum engineering and its relation to electrical and electronic engineering. We then discuss qubit modelling and existing solutions. The particular example we focus on in this paper is related to semiconductor CMOS charge qubits. For this reason, we overview the physical models and equivalent circuit model of this type of qubits.