A thermal sensing system includes a circuit having a layout including standard cells arranged in rows and columns. First and second current sources provide first and second currents, respectively. The thermal sensing system includes thermal sensing units, first and second switching modules, and an analog to digital converter (ADC). Each thermal sensing unit is configured to provide a voltage drop dependent on a temperature at that thermal sensing unit. The first switching module is configured to select one of the thermal sensing units. The second switching module includes at least one switch controllable by a control signal. The at least one switch is configured to selectively couple the thermal sensing units, based on the control signal, to one of the first and second current sources, via the first switching module. The ADC is configured to convert an analog voltage, provided by the selected thermal sensing unit, to a digital value.