We propose the optical transceiver having reference clock generator and CDR with delayed data topology in this paper. The 125MHz reference clock of optical transmitter have been extracted from 10 × 250 Mb/s data arrays. The clock extraction of reference clock generator is achieved by summing the edge information of the each data. Moreover, our optical transmitter includes 2-stacks NMOS serializer scheme rather than 3-stacks conventional scheme to achieve high speed operation. In optical receiver design, we employ a novel CDR with delayed data topology to overcome the problems in conventional CDR such as instability in locking state, nonlinearity output proportional to phase difference, false locking at harmonic frequency. The optical transceiver is designed by using of 0.35μm CMOS technology.
We propose a new model of the rate equation for the time domain analysis. A modulated signal is analyzed by the rate equation using the finite difference method (FDM) in time domain. For the analysis of modulated optical signal, an injection current term in the rate equation is altered to an appropriated electrical term either for analog or digital signal. The bandwidth, transmission characteristics and nonlinearity of laser diodes are analyzed by the proposed rate equation model.
Optical interconnection is recent issue for high-speed data transmission. The limitation of high-speed electrical data transmission is caused by impedance mismatching, electric field coupling, microwave loss, and different length of the electrical signal lines. To overcome these limitations, the electrical signal in the current electrical system has to be changed by the optical signal. The most suitable optical source in the OPCB (Optical Printed Circuit Board) is VCSEL (Vertical Cavity Surface Emitting Lasers) that is low-priced and has the characteristic of vertical surface emitting.
In this paper, we propose an electrical model of the VCSEL as E/O converting devices for the OPCB. The equivalent circuit of the VCSEL based on the rate equations includes carrier dynamics and material properties. The rate equation parameters are obtained by full analysis based on rate equation and experiment results. The electrical model of the VCSEL has the series resistance determined by I-V characteristic curve, and the parallel capacitance by the parasitic response of the VCSEL chip. The bandwidth of the optical interconnection is analyzed considering those parameters. We design and fabricate the optical transmitter for OPCB considering proposed electrical model of VCSEL.