In this paper, charge-modulated field effect transistor based detection circuit is presented for the purpose of electrical detection of DNA hybridization. The readout circuit consists of a drain follower and a compensated differential amplifier. It is able to achieve a voltage gain of 56.94 dB in the frequency range up to 6.79 kHz using 0.18μm Silterra CMOS process. The compensation technique is used in the detection circuit in order to improve the phase margin to 52.66o. The proposed potentiometric biosensor eliminates the need for a reference electrode which can offer great potential for miniaturized sensor array that would enable a massive parallel detection of DNA assay.

This study designs a low-voltage, label-free and fully integrated impedance-based biosensor using standard complementary metal oxide semiconductor (CMOS) technology to compute both capacitance and resistance of the electrode-electrolyte interface. The proposed biosensor circuit is composed of a common-gate transimpedance amplifier (CG-TIA) with two quadrature phase Gilbert cell double-balanced mixers and finally integrated with microelectrode using 0.18 µm Silterra CMOS technology process. The output value of the readout circuit was used to estimate the magnitude and phase of the measured admittance. The developed CG-TIA can achieve a gain of 88.6 dB up to a frequency of 50 MHz. The overall dynamic range was approximately 116 dB.

The purpose of this research is to design a low power integrated complementary metal oxide semiconductor (CMOS) detection circuit for charge-modulated field-effect transistor (CMFET) and it is used for the detection of deoxyribonucleic acid (DNA) hybridization. With the available CMOS technology, it allows the realization of complete systems which integrate the sensing units and transducing elements in the same device. Point-of-care (POC) testing device is a device that allows anyone to operate anywhere and obtain immediate results. One of the important features of POC device is low power consumption because it is normally battery-operated. The power consumption of the proposed integrated CMOS detection circuit requires only 14.87 mW. The detection circuit will amplify the electrical signal that comes from the CMFET to a specified level in order to improve the recording characteristics of the biosensor. Self-cascode topology was used in the drain follower circuit in order to reduce the channel length modulation effect. The proposed detection circuit was designed with 0.18µm Silterra CMOS fabrication process and simulated under Cadence Simulation Tool.