Design Of Dual SPDT Analog Switch

The design of low-voltage single-supply dual SPDT analog switch is presented in this thesis which comes from an engineering practice project. The chip is mainly applied in communication systems and portable products. For example, audio and video signal routing, battery-powered systems and so on.Four modules are included in the SPDT analog switch, for example, MOS switch circuit, driver circuit, buffer circuit, and ESD protection circuit. The design of a dual channel MOS switch, one NO switch and one NC switch with different switching time, is presented in the thesis. And the substrate bias is developed based on the traditional means in order to achieve the relevant design indexes. Then the design of a high efficiency switch driver is finished. This driver generates a pair of complementary signals to drive the MOS switch and makes the break-before-make switching is available. Several schemes of input/output buffer design are put forward, and they can effectively eliminate input noise. Then several solutions of the ESD protection are advanced, and the circuit is well protected from the damage caused by ESD by inserting ESD protection modules between pads.The simulation results show that the relevant design indexes of this device have been successfully achieved, such as fast switching speed (tON: 43ns,tOFF: 3ns), short break-before-make interval (tD: 5ns), low charge injection (QNO: 310C, QNC: 110C), and low on-resistance (RNO: 0.91?, RNC: 0.65?).