DNA detector is one of the main way to use in order to detect diseases, preventing crime and so on. The DNA detecting process is limited due to the bulky and expensive existing DNA detector machine. As the demand of the small, portable and inexpensive biosensor for point-of-care testing aid and medical diagnostic, the research and development of biosensor are increasing exponentially every year. The aim of this work is to develop an on-chip Complementary Metal Oxide Semiconductor (CMOS) biosensor circuit based on the charge-modulated field effect transistor (CMFET) for a label-free deoxyribonucleic acid (DNA) detection. This project focusing on low voltage and low power design potentiometric DNA detection circuit. Overall of detection circuit consists of two main circuits which are self-cascode source drain follower and two-stage differential amplifier. The proposed detection circuit is designed and simulates using 0.13 µm Silterra CMOS fabrication with 1.2 V supply. The power consumption of the improved source-drain follower circuit is 1.36 µW and with gain of 0.998 dB. The two-stage differential amplifier achives a voltage gain of 56.02 dB and high common mode rejection ration (CMRR) of 90 dB
