Patent ID: 6836170
Filing Date: 2004-12-28
Classification: H03H

Abstract:
An impedance trimming circuit comprising:a common bias section composed of a first series circuit having a first resistor and a second resistor connected in series via a first node and a first operational amplifier having a first input terminal being inputted a reference voltage, a second input terminal connected to the first node, wherein an output signal of the first operational amplifier controls a voltage of the first node; and an impedance trimming section composed of a second series circuit having a third resistor and an impedance dummy resistor connected in series via a second node, a comparator having a first input terminal connected to the first node and a second input terminal connected to the second node, a code control circuit latching an output signal from the comparator to generate switching codes, which controls a value of the impedance dummy resistor, wherein the switching codes control a value of a target impedance trimming resistor.