At present, Acousto-Optic Tunable Filter (AOTF) infrared spectrometers have attracted more and more attention. The speed of obtaining spectral curves not only depends on the number of spectral sampling points, but also depends on the rate of spectral sampling. A circuit design method based on a precision low noise integral amplifying circuit is presented. Compared with the traditional lock-in circuit, this circuit has a higher sampling speed which is up to microsecond order of magnitude in theory. According to the above theory, the data are collected with the same signal intensity and different integral time first. Then, the data are collected with different signal intensity and fixed integral time. The experimental results show that the circuit has its sampling speed up to 10² μs magnitude.}