A novel controlled slew-rate (CSR)output driver is presented to reduce the simultane-ous switching noise (SSN). The SSN effects on digitalcircuits and the noise immunity of the input driverare investigated. Compared with traditional CSR out-put driver, a combination of the feedback as well asthe distributed and weighted structure is adopted toimprove the noise performance of the CMOS outputdriver. A prototype circuit is implemented in 0.6-μmCMOS technology with about 3.6 times noise ampli-tude reduction in the ground line, which complies withthe simulation results of HSPICE.