Semiconductor integrated circuit having switching transistors and varactors

摘要

A CMOS line driver is made up of p- and nMOS transistors. A pMOS varactor is interposed between the source of the pMOS transistor and a power supply, while an nMOS varactor is interposed between the source of the nMOS transistor and ground. The sizes of each of these MOS varactors may be the same as those of the p- or nMOS transistor. Alternatively, each of these MOS varactors may have a channel area twice greater than that of the p- or nMOS transistor. The inverted version of a signal input to the line driver is supplied to the gates of the MOS varactors. In this manner, the MOS transistors, making up the line driver, can switch at a high speed.