There is an issue with the N-channel MOSFET inside the switch, however. This N-MOSFET needs a certain gate-to-source voltage (V_GS) to create the conducting channel. However, current through the NMOS and the load can cause a voltage drop at the load which reduces the V_GS and causes the NMOS to stop conducting, or to increase the ON resistance and reduce output voltage range. The solution is to add a series of diodes and capacitors inside the switch. This is called a charge pump. Switching the input of this charge pump between ground and a higher voltage U_e stores a charge alternately in C1 and C3 and then in C2 and C4, thus pumping up the output voltage through each switching iteration. By means of this charge pump, the NMOS gets a higher source-to-gate voltage and therefore the switch can pass signals that are higher than V_CC. This feature is used in the CB3Q family of analog switches.