A 25 Gbps VCSEL driving ASIC: an attempt for ultra-high-speed front-end readout applications

This paper presents the design and the test results of a 25 Gbps VCSEL driving ASIC fabricated in a 55 nm CMOS technology as an attempt for the future very high-speed optical links. The VCSEL driving ASIC is composed of an input equalizer stage, a pre-driver stage and a novel output driver stage. To achieve high bandwidth, the pre-driver stage combines the inductor-shared peaking structure and the active-feedback technique. A novel output driver stage uses the pseudo differential CML driver structure and the adjustable FFE pre-emphasis technique to improve the bandwidth. This VCSEL driver has been integrated in a customized optical module with a VCSEL array. Both the electrical function and optical performance have been fully evaluated. The output optical eye diagram has passed the eye mask test at the data rate of 25 Gbps. The peak-to-peak jitter of 25 Gbps optical eye is 19.5 ps and the RMS jitter is 2.9 ps.

The CDAU — a common data acquisition unit for the radiation imaging detectors at HIRFL-CSR

A common data acquisition unit (CDAU) has been designed for data transmission in the radiation imaging detectors in the Heavy Ion Facility in Lanzhou (HIRFL). With a bandwidth of 64 Gbps, this CDAU can meet the need for most of the experiment. The CDAU can connect four front-end readout cards (FECs) through optical links for data collection, packaging, and transmission. This CDAU is based on the PCI Express (PCIe) Gen3 bus, using Xilinx Kintex Ultrascale series FPGA, combined with the periphery circuits design to complete the data acquisition system. This paper will discuss the design and performance of the CDAU.

Optical Inter-Satellite Link over Low Earth Orbit: Enhanced Performance

Space communication systems are traditionally operated with microwave in satellite-to-satellite links. Now, more efficient and reliable operation is required, which lead to use optical links for Inter Satellite Links (ISLs). This paper investigates the system performance of an optical ISL proposed between satellites over Low Earth Orbit (LEO). In this study, the proposed link is simulated to obtain a maximum bit rate and minimum bit error rate (BER) over different links distances. The system performance is improved by investigating its dependency on the photo detector type, operating wavelength, transmitted optical power, RZ and NRZ schemes. Our work results that best Q- factor are approximately 40 leading to a minimum BER for the LEO orbit, at 600 km when utilizing an APD. While at our investigation of the system performance at visible light bands, it is found that Q-factor will be approximately 60 achieving minimum BER with neglecting the eye-safety precautions in addition to the ability to transmit 2 Gbps at 10−9 BER within many bands.