Impedance-based physical unclonable function

According to various aspects, systems and methods for providing a soft-decoding physical unclonable function are provided. According to one embodiment, PUF circuitry includes circuit elements with impedance values that are used to generate a PUF value. For example, one or more resistors may be connected to a voltage source. The resistors may generate a resulting voltage signal that is measured and indicates a ratio of the impedance values of the resistors. Due to manufacturing variations, each impedance value may be unique, such that the impedance values may be used to provide a unique number sequence. Each ratio value may be converted into a single bit or multi-bit digital value through digitization, for example with a comparator and/or an analog to digital converter, and the series of digital values may represent or be used to generate a unique number sequence.