3.7.2 Circuit Elements

In this section we describe the passive components such as resistors and capacitors and non-volatile R/W memory.

Resistors in CMOS Technology

Resistors include diffused, polysilicon and well resistors. The diffused layer that used to form the source and drain of MOS devices can be used to form a diffused resistor. Similarly the polysilicon required in silicon gate MOS technology can be used to form resistors. The nominal sheet resistance is in the order of 20 / Ž to 80 / Ž . To reduce the sheet resistance a silicide layer is deposited on the top of the polysilicon. The well region in the CMOS technologies can also be used as resistors. It is relatively lightly doped region and this resistor provides a sheet resistance of the order of 10k / Ž . The MOS transistor biased in the triode region can be used in many circuits to perform the function of a resistor. In the drain-source resistance calculated by differentiating the drain current in the triode region with respect to the drain-source voltage.