Abstract: A method of designing improved CMOS input circuits by understanding and selecting appropriate drive strength for a CMOS output from a previous stage. The method involves modeling the net using HSPICE and including a transit time term to accurately model charge storage, then size drivers as needed to keep the V.sub.ss clamps out of forward conduction. Excessive ringing can cause data errors in the input stage if unterminated, falling edge transitions in such a net can turn on a receiver's V.sub.ss clamp diode (stored charge in the V.sub.ss clamp diode combined with the line's inductance and the receiver's capacitance form an energized resonant circuit which can release energy at a time to cause a data glitch). Currently, XNS simulation miscalculates the ring amplitude by a factor of three. Driver scaling and termination can eliminate the problem by keeping the receiver's V.sub.ss clamp out of forward conduction. Driver sizing can control the problem.

Abstract: An analog interface for a PC module and an electronic device which communicate through a standard 68-pin PC card digital interface. The PC module includes a cellular phone radio and an analog modem that provides cellular communication capabilities to both a notebook computer and a telephone handset that includes a PC card slot. The PC module and the notebook computer have modified the standard 68-pin PC card interface, while remaining compliant with the standard interface, to enable voice applications in the notebook computer. The PC card interface is modified by reassigning pin assignments on the 68-pin connector through the use of a switch and audio lines in both the notebook computer and in the PC module.