Patent ID: 7071711
Filing Date: 2006-07-04
Classification: G01R

Abstract:
1. A method for determining a ratio of an actual value of an RC time constant of an RC network in an integrated circuit to a desired value of the RC time constant of the RC network, the method comprising the steps of: providing a first reference RC network with a first resistor and a first capacitor and a second RC network with a second resistor and a second capacitor, the first and second RC networks being oppositely connected in a circuit between first and second supply potentials, where time constants of the first and second RC networks are equal; defining a normalized RC time constant for the first and second reference RC networks; implementing successive charge and discharge cycles during a predetermined evaluation period, where the first and second capacitors are charged in a cycle during a charge time until a potential at a first node common to the first resistor and the first capacitor of the first reference RC network approximately corresponds to a potential at a second node common to the second resistor and the second capacitor of the second reference RC network, and where the first and second capacitors are subsequently discharged in a cycle for a discharge time; matching the predetermined evaluation period to the normalized RC time constant such that where the RC time constant of the first and second reference RC networks corresponds to the normalized RC time constant then a predetermined number of charge and discharge cycles can be implemented during the predetermined evaluation period; determining the number of charge and discharge cycles actually implemented during the predetermined evaluation period; and providing a value that corresponds to a quotient of the actual number of charge and discharge cycles and the predetermined number of charge and discharge cycles to provide a measure of the ratio of the normalized RC time constant to the RC time constant of the first and second reference RC networks.