Method and device for offset-voltage free voltage measurement and adjustment of a reference voltage source of an integrated semiconductor circuit

A method for measuring and setting of a voltage of an adjustable internal reference voltage source of a dynamic semiconductor memory, which comprises:

• comparing a reference voltage to an external comparison voltage with a comparator having two inputs;
• forming a measured value for the reference voltage that is to be set in accordance with a result of the comparison;
• switching a commutator by one of a clock-control and a software-control to alternatively apply the reference voltage and the external comparison voltage to the two inputs of the comparator at the same time;
• varying one of the reference voltage and the external comparison voltage in a direction of a setpoint voltage value until the comparator output changes its logic value at each switched stage of the commutator;
• buffering the voltage values present for each switched state of the commutator when the logic value of the comparator output changes and respectively varied in the preceding step;
• forming an average value for the reference voltage from the stored voltage values;
• and
• setting the reference voltage as a function of the average value formed in the preceding step.

A device for measuring and setting of a voltage of an adjustable internal reference voltage source of an integrated semiconductor circuit, comprising:

• an internal reference voltage source providing an internal reference voltage;
• an external comparison voltage source providing an external comparison voltage;
• a comparator having two comparator inputs and a comparator output for outputting a logic value;
• a commutator having switched stages, a switch input, two commutator inputs, and two commutator outputs;
• each of said two commutator inputs connected to a respective one of said internal reference voltage source and said external comparison voltage source;
• each of said two commutator outputs directly connected to a respective one of said two comparator inputs;
• said commutator alternately switching said two comparator inputs between said internal reference voltage and said external comparison voltage;
• said comparator comparing said internal reference voltage to said external comparison voltage;
• a switch control having a switch output connected to said switch input of said commutator for alternatively applying said internal reference voltage and said external comparison voltage to said two comparator inputs at the same time;
• and
• one of said internal reference voltage and said external comparison voltage are varied in a direction of a setpoint voltage value until said comparator output changes said logic value at each switched stage of said commutator.

A device for measuring and setting of a voltage of an adjustable internal reference voltage source of a dynamic semiconductor memory, comprising:

• an internal reference voltage source providing an internal reference voltage;
• an external comparison voltage source providing an external comparison voltage;
• a comparator having two comparator inputs and a comparator output for outputting a logic value;
• a commutator having switched stages, a switch input, two commutator inputs, and two commutator outputs;
• each of said two commutator inputs connected to a respective one of said internal reference voltage source and said external comparison voltage source;
• each of said two commutator outputs directly connected to a respective one of said two comparator inputs;
• said commutator alternately switching said two comparator inputs between said internal reference voltage and said external comparison voltage;
• said comparator comparing said internal reference voltage to said external comparison voltage;
• a switch control having a switch output connected to said switch input of said commutator for alternatively applying said internal reference voltage and said external comparison voltage to said two comparator inputs at the same time;
• and
• one of said internal reference voltage and said external comparison voltage are varied in a direction of a setpoint voltage value until said comparator output changes said logic value at each switched stage of said commutator.