In this paper, a well-known bridge-circuit design for high-precision calibration using voltage controlled
resistors is newly proposed. This circuit utilizes a valanced resistor ratio characteristic as a precision
instrumental approach by controlling and tuning the resistance value of the resistors, that being replaced
with passive resistors in a bridge circuit. Because the resistance of a resistor is controlled by an external
voltage, the voltage value for balanced condition can be used to acquire the external or internal unbalanced
condition. A 0.0001% change of a resistance on 50㏀ resistance generates approximately ±1㎶ change. It is
verified through simulations that the proposed circuit using voltage controlled resistance in a bridge circuit
can detect a difference of a ppm-level that is significantly low.