Patent ID: 7920011

Claim:
A voltage trimming circuit comprising: an input stage having a first input, a second input and an output, wherein the first input is to receive an input voltage, the second input is connected to a connection point and the output is to provide an output voltage based on a difference between voltages of the first input and the second input; an up-trimming resistor ladder connected between the output of the input stage and the connection point; a down-trimming resistor ladder connected between a ground potential and the connection point, wherein each of the up-trimming and the down-trimming resistor ladder comprises: a plurality of trimming resistor stages, wherein the resistance of the N-th trimming resistor stage is substantially 2 N-1 times of the resistance of the first trimming resistor stage; and a reference resistor connected serially to the plurality of trimming resistor stages; and a control means to control the resistance of the up-trimming resistor ladder and the down-trimming resistor ladder; wherein the output voltage is not trimmed when the resistance of the up-trimming resistor ladder and the down-trimming resistor ladder are equal, the output voltage is up-trimmed when the control means makes the resistance of the up-trimming resistor ladder larger than the resistance of the down-trimming resistor ladder and the output voltage is down-trimmed when the control means makes the resistance of the down-trimming resistor ladder larger than the resistance of the up-trimming resistor ladder.