Patent ID: 8618839

Claim:
A method for utilizing a sense amplifier to select a suitable circuit, the method comprising the steps of: selecting a voltage gain of a sense amplifier having input terminals, auxiliary inputs, an output, an array of resistive loads, and an amplifier gain selector; adjusting voltage into the auxiliary inputs to nullify direct current (DC) offset voltage of the sense amplifier; connecting the input terminals of the sense amplifier to output terminals of a circuit that is within a group of circuits; determining if the circuit generates a voltage greater than or equal to a configurable reference voltage, based on the output of the sense amplifier; wherein the selected circuit includes at least one single field effect transistor comparison physically unclonable function (SFC circuit) that is selected to generate an authentication key; wherein components of the selected circuit are selected from an array of SFC circuit components that is greater than the number of SFC circuit components needed to generate the authentication key; wherein each component included in the array of SFC circuit components is selectively connectable to the output; wherein data bits included in the authentication key are generated based on the integrated circuit components included in the sense amplifier; wherein the SFC circuit is selected such that the SFC circuit generates a strong random output voltage signal that does not change polarity due to variations in the operating temperature of the SFC circuit; and wherein a resistive load is selected from the array of resistive loads to provide a differential voltage.