Patent ID: 6812689
Filing Date: 2004-11-02
Classification: G01R

Abstract:
A method for measuring and setting of a voltage of an adjustable internal reference voltage source of an integrated semiconductor circuit, the method which comprises:a. providing a reference voltage from the internal reference voltage source and an external comparison voltage to a respective one of two voltage inputs of a commutator having two voltage outputs and being alternatively switchable to a first and a second commutating state via one of a clock signal and a switching signal from a control unit, both signals being applied to a clock input of the commutator; b. switching the commutator to the first commutating state; c. applying, in the first commutating state, at the same time, via the voltage outputs of the commutator, the reference voltage and the external comparison voltage, respectively to a first and second input of a comparator having an output; d. comparing the reference voltage and the external comparison voltage via the comparator in first commutating state; e. varying, via the control unit, one of the reference voltage and the external comparison voltage in a direction of a setpoint voltage value of one of the reference voltage and the external comparison voltage until the control unit detects a changing logic value of the comparator output; f. buffering, via the control unit, the voltage value varied in the preceding varying step and present for the current commutation state of the commutator upon the control unit detecting the changing logic value of the comparator output; g. switching the commutator to the second commutating state; h. applying, in the second commutating state, at the same time the reference voltage and the external comparison voltage via the voltage outputs of the commutator, respectively to the first and the second input of the comparator; i. comparing, in the second commutating state, the reference voltage and the external comparison voltage via the comparator; j. repeating steps e and f; k. forming, via the control unit, an average value for the reference voltage from the buffered voltage values; and l. setting the reference voltage as a function of the average value formed in the preceding step.