Testing Circuit of a Longtime-Constant Circuit Stage and Corresponding Testing Method

A method can be used for testing a charge-retention circuit for measurement of a time interval having a storage capacitor coupled between a first biasing terminal and a floating node, and a discharge element coupled between the floating node and a reference terminal. The discharge element is configured to implement discharge of a charge stored in the storage capacitor by leakage through a corresponding dielectric. The method includes biasing the floating node at a reading voltage, detecting a biasing value of the reading voltage, implementing an operation of integration of the discharge current in the discharge element with the reading voltage kept constant at the biasing value, and determining an effective resistance value of the discharge element as a function of the operation of integration.