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.