Realtime signal processing of a compact high-speed photo-electron detection system

A photo-electron detection system with 32 PIN photodiodes in 1D array has been designed and implemented within 16cm width. There are mainly two parts in this system: the photodiode frontend with weak signal modulation and sampling, the signal processing backend with parallel signal processing and data transfer. The weak current signal of 32 PIN photodiodes' output is first amplified for about 104 times, and then sampled at 75MHz with 12bits digital precision. The weak signal modulation circuit has a good response to signal with pulse width larger than 20ns or lead edge longer than 10ns. The signal processing module receives the 32-channel signal at data-rate of 900Mbps per channel and caches them real-time inside the FPGA. The data bandwidth of the signal processing module reaches up to 28.8 Gbps. Sampled data is then transferred to host computer through a USB2.0 interface.