An Ultra Wide Band RF Sampling System Based on Photoelectric Hybrid Technology

In the field of receiver, traditional heterodyne receiver is not able to meet needs for various reasons, and many applications are requiring the ability for direct sampling of high frequency and high bandwidth microwave signals. Currently, the commonly methods using to improve the conversion rate of ADC are limited by the physical limit of the transfer rate of semiconductor carriers, thus the front-end analog bandwidth is difficult to reach beyond 10GHz. However, the input bandwidth and quantization accuracy can be improved by using optical sampling. In this paper, an ultra wide band RF sampling system is realized by combining optical sampling and electrical quantization with photoelectric hybrid technology. Optical sampling of ultra-short optical pulses replaces the traditional sampling/holding circuit, enabling ultra-high speed sampling of ultra-wide band signals, and then uses the electronic ADC to encode the optical sampling signals in multi-channel time-division interleaved quantization, thus realizing the direct digitization of high frequency signals. In addition, linearization in the digital domain can further improve system performance. The system enables direct sampling of 40GHz microwave signals with a signal-to-noise ratio greater than 40dB.