PCB Designed in Compliance With the QSFP Card Edge

PCB Designed in Compliance With the QSFP Card Edge

Some sort of progressive switch toward cloud computing as well as prevalent utilization of mobile phones has pushed an outburst in Internet traffic, which has made fiber optic interconnection a standard means even for the intra-traffic in the Internet data center, fiber optical transceivers for communication contribute to high-speed high-throughput data traffic.

Introduction

PCB was designed in compliance with the QSFP card edge requirement. An electrical circuitry  was designed to meet the requirement of a hot-pluggable electrical connection. Electrical  differential transmission lines on the PCB were carefully designed by performing   electric-magnetic (EM) simulations to realize a wide enough modulation bandwidth.  The optical module is mounted on the PCB together with other electronics components by a SMT machine and then soldered through a reflow-process. An SMT solder-reflow process is the best  approach to populate the PCBAs in high volume production. Accordingly, it derives reducing an assembly cost for the module.

The fabricated PCBAs were tested on a commercially- available QSFP evaluation board, the PCBA was connected to a QSFP-compliant edge connector. A micro-control unit (MCU) was mounted to control adequate driving parameters. The driving conditions are automatically adjusted by a feed-forward circuit with a look-up table stored in the MCU through the inter-integrated circuit (I2C) communication interface. All status motors are green and all functionalities work correctly. Removing the dust cap, a standard MT ferule was connected to the microlens of the module and fixed by a customized clip with an adequate mechanical force. The PCBA was built in a die-cast QSFP housing where the top surface of the module is thermally connected to the inner surface of the housing, and then a MMF cable was connected to the optical modules

 (Photograph of a PCBA connected to a commercially-available QSFP evaluation board)

To characterize a link performance of the AOC,

First, measuring the eye diagrams of the optical signal from the transmitter, The optical signals were transmitted over an OM2 fiber of 5 m to the receiver.

Secondly, measuring eye diagrams of electrical signals from the receiver ,the optical and electrical eye diagrams are clearly opened.

Subsequently,measuring BER bathtub curves for the AOC link and the results ,Compared with the BER bathtub curves for a link test of the 4-channel transceiver module , the AOC link keeps a quite similar total jitter margin.

Therefore, the PCB design was well-done and all functionalities required for a QSFP AOC works correctly. It is confirmed that the AOC can be employed in actual applications.

(QSFP+ AOC Cable)

Summary

Solderable 4-channel VCSEL-based optical transceiver module perfect for high-volume production of QSFP AOC. The 4-channel module can be simply mounted on a PCB together with other electronics components through a solder reflow process.

If you are interested in UTOPTICAL compatible module or full range of optical transceivers & cables ,please visit :UTOPTICAL Online Store.