Optoelectronic Module with Integrated Transceiver and Mux-Demux for Optical Interconnect Applications

Nga Thi Hang Nguyen,Jamshid Sangirov,Ikechi Augustine Ukaegbu,Hyo-Hoon Park

doi:10.11648/j.ajop.20190702.11

Abstract

The design, development and improvtableement in electronic devices and components have led to the further miniaturization of the system devices and their interconnecting interfaces. Hence, reducing the size of the transmitter (Tx) chips, receiver (Rx) chips and associated components play an important role in designing a reduced/small sized optoelectronic modules for optical interconnect applications. Some of the associated components include multiplexer, demultiplexer, clock and data recovery circuits (CDR), etc. Therefore, in this paper we present an optoelectronic module with integrated transceiver (Tx-Rx) and multiplexer-demultiplexer (mux-demux) with the aim of reducing the total area occupied by the chips. The topology is based on sharing common blocks between Tx and Rx as well as Mux and Demux for saving chip area, power consumption and board area. Based on this topology, a design of 2-channel Tx/Mux and Rx/Demux is realized in a 0.18 μm CMOS technology. The measurement results show clear output eye diagrams at 2.5 Gbps with the voltage swing of 375 mV<sub>pp</sub> from the Rx/Demux. The combined solution would save the chip area and power consumption of 10% and 23%, respectively, compared to discrete circuits implementations. Using this topology, a high efficient bidirectional optical link could be implemented in modern computer and other green IT applications.

Highlights

System clock speed is rapidly increasing and the copper-based links on printed circuit boards (PCBs) constitute the bottle-neck of the high speed signal transmission between CPU and memory in modern computer systems
A transmitter (Tx) module consists of a Tx chip and a Vertical Cavity Surface Emitting Laser (VCSEL) for transmitting and a receiver module (Rx) consists of an Rx chip and a photodiode (PD) for receiving
The topology is special for replacing multi parallel time interleaving electrical links using a single optical link

Summary

Introduction

System clock speed is rapidly increasing and the copper-based links on printed circuit boards (PCBs) constitute the bottle-neck of the high speed signal transmission between CPU and memory in modern computer systems. Several implementations of data transfer (sending and receiving data) between the CPU and memory use time multiplexing In traditional topologies, both the Tx and Rx are implemented on separate chips without sharing a common block for transmission. In order to increase throughput while transmitting data of the same type, multiple transmit pins and multiple receive pins need to be used over a single transmission line To solve this problem, a multiplexer (Mux) and a demultiplexer (Demux) can be used to convert the slow speed parallel data to a serialized high speed data in the transmitting side and vice versa in the receiving side to replace many electrical data line using a single optical link. The chip design as well as the measurement results and chip photographs for integrating 2:1 Mux-Tx and 1:2 Demux-Rx chips are presented

The Proposed Optoelectronic Module

Circuit Design and Implementation

Experimental Results

Conclusion