A device includes a circuit that generates a first current associated with a voltage of a region of a semiconductor substrate, a second current associated with a temperature of the region, a third current associated with a first process parameter of the region, and a fourth current associated with a second process parameter of the region. A multiplexer of the device receives the first, second, third, and fourth currents and selects the currents one by one and periodically. A ring oscillator of the device is coupled to the multiplexer and receives the first, second, third, and fourth currents one by one and periodically, from the multiplexer. The ring oscillator oscillates at oscillation frequencies that are based on the received current from the multiplexer. The voltage, temperature, and the first and second process parameters of the region are determined based on the oscillation frequencies.