Infrared detector development into the third generation, with a large array, long line array applications as a typical representative, of which the long line array is usually achieved using the splicing structure. The scale of the monolithic circuit involved in splicing is also expanding, and the line frequency is increasing. The increase in array specifications brings about the extension of the signal transmission link, the line frequency enhancement puts forward new requirements for the readout rate, and these must also take into account the detector's low-temperature applications, requiring the readout circuit to put forward a more reasonable and effective countermeasures. In this article, a novel output method is explored for long line array, which can suppress transmission noise by full differential output, while the differential module conversion module is independent of the main detector chip. The readout rate is significantly increased without affecting the overall thermal consumption of the chip. Depends on this design, the readout rate of line array is increased to 20 MHz, and for 1k scale, the line frequency reaches 19 kHz.