If linearity of a semiconductor photodetector is a critical issue in an application like in radiometry, spectrophotometry, etc. the detectors are used in the so called current measurement mode. In this mode the detector is directly connected to a current-to-voltage converter, consequently in an ideal situation all the photogenerated charge carriers appear on the feedback resistor of the converter and produce a voltage drop. Photovoltaic detectors are short circuited by the converter, the built in electric field of the detector transfers the generated carriers to the converter. On the other hand photoconductive detectors should be biased externally by a constant voltage to produce an internal field for the transport of the charge carriers. Some applications need great area detectors, that especially in the IR wavelength region show low shunt resistance values. Ge, InAs, InSb, PbS, PbSe, HgCdTe, etc., have many decades lower shunt resistance values than that of a Si or InGaAs detector operating in the visible or near infrared region. If high sensitivity is needed than a high value of the feedback resistor is required that decreases the closed loop gain, consequently the settling accuracy. Bootstrapping of the detectors virtually increases the shunt resistance and so restores the decreased closed loop gain and settling accuracy. The bootstrapping technique will be shown and the noise characteristics will be analyzed and compared to the traditional solutions.