Current mirrors are one of the most important components of integrated circuits. As their name suggests, they reflect the input current and carry it to other parts of the circuit which simplifies it’s architecture. Their function is based on a premiss that the same current flows through two geometrically same transistors if they are operating at the same temperatures. There are different implementations to the current mirrors, depending on customer’s needs. For example, the simple MOSFET current mirror is made up of two transistors in diode connection which enables the 𝑈𝐺𝑆 voltages to have the same values in the input and in the output. The cascode MOSFET current mirror has the ability to neutralize the channel length modulation. Widlar current mirror enables generating small values of the output current without usage of large resistor values. Wilson current mirror has very large output resistance which makes the reflecting current less dependant on output voltage. In this final paper it is tried to describe several types of current mirrors in words and mathematically. Also, six simulations are given to help understand the influence of randomly selected currents and dimensions of transistors on current gain. Simulations of Widlar and Wilson current mirrors are used to question if equations written in previous chapters are valid in simulated conditions. Results are compared to the calculated ones. Key words: saturation, current mirror, referent current, output current, reflection coefficient, output resistance, output voltage, Widlar’s current mirror, Wilson’s current mirror