Very high sensitivity CMOS circuit to track fast biological current signals

The paper presents a novel transimpedance amplifier to sense very small and fast biological signals even in the presence of a dc leakage current as high as few tens of nanoamperes. The circuit, integrated on standard 0.35 mum CMOS technology, has a core based on the series of an integrator and a differentiator stage but features an additional time continuous feedback loop to discharge the standing current from the device under test, thus ensuring an unlimited measuring time opportunity with no need of reset pulses. This amplifier is ideal in a wide range of applications in miniaturized single chip systems such as implantable electronics, single molecules characterization or sensor interfaces, where very high sensitivity is requested together with minimum amount of biological matter and of analyte.