Noise effects in field-effect transistor biological sensor detection circuits

Affinity-based biological sensor field-effect transistors (BioFETs) exhibit a large amount of noise in their drain current under constant bias. In this work, we use SPICE to simulate the effect of sensor noise on a differential pair amplifier detection circuit. This is accomplished by the generation of a realistic noise signal with 1/f power spectrum which is applied to the back gate and reference electrode of a nanoribbon BioFET sensor. The resulting output signal from the transient simulation is time-averaged to obtain the noise rms amplitude. The ability to distinguish the sensor signal from the noisy environment is examined for various amounts of noise power and integration time. Corresponding minimum theoretical direct detection limits for of Biotin-Streptavidin attachment and DNA hybridization are also provided, along with discussion of possible methods to reduce the noise effects.