This paper presents a new current comparator with a novel dual-modulation concept. The dual modulation concept has the ability to increase the accuracy quite substantially. The output voltage range still reaches its maximum peak value of 1.2V when the differential current is only 0.6 nA with a 3.3 V supply voltage. In addition to high-accuracy, the design reduced the input impedance of the proposed current comparator to 1⁄(gm 2 ro) even without the use of an operational amplifier (OPA). Moreover, the novel current comparator was implemented using TSMC 0.35 μm Mixed-Signal 2P4M Polycide 3.3V models with an active area of 0.0024 mm 2 .

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-This paper presents a novel readout circuit with potentiostat for amperometric chemical sensors that has wide output current range and has low power consumption, with its application towards the implantable glucose sensing system. This new design of electrochemical interface circuit operates in current-to-current transfer mode, has low input impedance characteristic and has stable loop gain unaffected by sensor resistance variation. Post layout simulations showed detection of redox current from 50 pA to 50 PA with power consumption from only 390 PW to 745 PW, while experimental verification using on-board prototype provided measurements from 10 nA to 50 PA, with 10 nA as the lowest capability of the semiconductor device analyzer used in the setup. This novel readout circuit was implemented using TSMC 0.35 Pm mixed-signal 2P4M 3.3 V CMOS technology with a chip area of 0.1767 mm 2 .