A voltage clamping system includes: (a) a first electronic device connected to a first power source and having a signal output node, a voltage clamp high node, and a voltage clamp low node, wherein the voltage clamp high node and the voltage clamp low node are coupled to a second power source different than the first power source; and (b) a second electronic device powered by the second power source and having a signal input node coupled to the signal output node of the first electronic device. The signal output node of the first electronic device is passively clamped, with low distortion, approximately rail-to-rail with respect to the second power source such that the second electronic device is protected from damage due to excessive voltage levels.

The present disclosure provides a level shifter including: a level shifter section that is driven by a first power source voltage, and that, in accordance with switching of an input signal of a voltage lower than the first power source voltage, switches an output signal that has been level-shifted, from the first power source voltage to a voltage lower than the first power source voltage; and a threshold voltage changing circuit that, in accordance with a switching direction of the input signal, changes a threshold voltage of the input signal for switching the output signal.

There is disclosed a Connected Synthetic Physically Unclonable Function (acronym CSPUF) made of a circuit configured to receive signals of one or more sensors and/or actuators in/of a computer device; determine one or more statistical properties of the noise distribution of the selected one or more of the sensors and/or actuators; receive data IN from one or more external data sources; determine one or more digital signatures (responses) from the statistical properties and the selected external data. In one embodiment, along a response R when challenged by a challenge C, the circuit is configured to receive data IN and/or to communicate data OUT from one or more external data sources. Developments describe uses and advantages of data IN and data OUT channels, e.g. static or dynamic calibration, options to disable the circuit. Other embodiments consider variants of interconnections of two CSPUF circuits, providing self-cycled, iterative, cascaded and other blockchain arrangements.