Pad signal detecting circuit in a semiconductor device for detecting a reference voltage in a high-speed interface

摘要

A pad signal detecting circuit for detecting a reference voltage input to a pad of a semiconductor device. This invention may be used in high speed terminated interfaces using a reference voltage, such as those using stub series termination logic (SSTL). The invention allows the manufacture of semiconductor devices having more than one type of interface, because the device can sense the type of interface which is connected to the pad and activate the appropriate interface circuitry. This feature eliminates the need to manufacture different devices for different types of interfaces, and it facilitates high volume and low cost production of semiconductor devices that are compatible with more than one type of interface circuitry.