| 摘要 |
A comparator is provided to compare the magnitude voltage of two signals with minute voltage difference by correcting a gain error of an operational amplifier. A comparator includes first and second switches(SW1, SW2), a first operational amplifier(100), third and fourth switches(SW3, SW4), a second operational amplifier(110), and a capacitor(C1,C2). The first and second switches selectively input the ground signal or the comparison signal. The first operational amplifier calculates and amplifies the signal of the first and second switches. The third and fourth switches are connected to the ground. The second operational amplifier amplifies the signal of the third and fourth switches. The capacitor stores the output signal of the first and second operational amplifiers in case the first to fourth switches are connected to the ground. The first and second switches select the comparison signal. The capacitor positively feeds backs the output signal of the first and second operational amplifiers to the second operational amplifier when the third and fourth switches are opened. A voltage level regulator is positioned between the first and second switches and the first operational amplifier. The voltage level regulator compares the source voltage which is the input transistor of the first operational amplifier with the previously set reference voltage. According to the comparison result, the voltage level regulator regulates the voltage level of the signal inputted through the first and second switches. |
