An input buffer with monolithic JFET in standard BCD technology for sensor applications

A new input buffer with monolithic integrated JFET in standard BCD technologies is presented in this work. The JFET has been implemented without any modification to the standard BCD process. An input buffer with PMOSFET was also fabricated for comparison. Measurements showed that the low-frequency input referred noise of the JFET input buffer is much smaller than that of the PMOSFET buffer. The proposed circuit can be applied to low-noise front-end amplifiers of sensors.