CMOS analog switch

• Main Author: STEINHAGEN WOLFGANG
• Format: Patent
• Language: English
• Published: 31.10.2006
• Subjects: BASIC ELECTRONIC CIRCUITRY; ELECTRICITY; PULSE TECHNIQUE

A CMOS analog switch is provided that can handle negative input polarity. The semiconductor substrate wherein the analog switch is formed has a substrate area of n-conductivity type. First and second p-channel transistors are formed in the n-conductivity substrate area and each have a gate, a source connected to the input terminal and a drain connected to the output terminal. The analog switch further has a comparator for comparing a voltage level at the input terminal with ground level, a switch driven by an output of the comparator to selectively connect the n-conductivity area with the signal input terminal for a positive input voltage level or to ground for a negative input voltage level, and control circuitry providing gate control signals for the first and second p-channel transistors. The inherent substrate diodes are effectively kept from becoming conductive.