Design and research of RS232 communication circuit used for 0.6um CMOS sensor IC

A RS232 transmitter interface circuit used for CMOS sensor IC has been developed in a 0.6mum CMOS technology, which makes it possible to integrate CMOS sensors and subsequent signal processing and communication interface circuits in a single chip. The positive and negative voltages (+7.6V/-6.1V under +5V single supply) are achieved with on-chip charge pump, which are used as supply of transmitter circuit. The transmitter acts as level and logic transfer unit and converts TTL/CMOS level to EIA/TIA RS232 level at 230.4kbps data rate under 3KOmega and 1000pF loads