Testing elements in a fast communication channel 100GB/s Final Presentation Spring 2010 Developers: Hanna Alam and Yousef Badran Project supervised by: Yossi Hipsh Technion - Israel Institute of Technology

Agenda  Brief Introduction  Project Goals  Transmitter and Receiver Schematic  Designing the Microstrip Line  Losses Considerations  Testing the Microstrip Line  Components and Suitable Devices  Conclusions and next steps

Introduction The Fast evolving high-speed digital systems in today’s technology and in daily life Using tools and technologies which we currently possess in order to create a more advanced design A method for breaching the 100 GB/s barrier is through channels with lower frequencies

Goals The ability to transfer information in a single 100GB/s rate channel between two units located on the same printed board Designing and characterizing the microstrip line Suggest theoretical and practical way to test the microstrip line in terms of signal integrity and internal losses

General Schematic

Unit1– Transmitter’s side Sharpening the signal Reducing tr/tf Reducing the bit time to 10ps Adding Different delay to each channel Buffer Sigma: Adding all of the 4 narrow signals 25GB/s 100GB/s

Unit1– Transmitter’s side Sharpening the signal to reduce rise and fall time: Problem : finding a suitable buffer In lower frequencies we use step recovery diodes, in higher frequencies the issue requires further researching

Unit1– Transmitter’s side Reducing the bit time is achieved by a mixer and a power divider Delay is required in order to achieve the desired result Also requires additional researching

Unit2– Receiver’s side Equalizer Splitting into 4 channels Filtering Data BuffersMonostable 100GB/s 25GB/s

Unit2– Receiver’s side The attenuation of the microstrip line is not uniform. The higher the frequencies the greater are the losses Equalizer - to compensate on the different losses preserving SI Monostable - to increase the bit time back to the original 40ps state

The µstrip Line primary objective is designing a microstrip line on a printed circuit board Our focus will be on a 15 cm long microstrip line. How to begin our design ?

Designing the µstrip First step is finding a suitable dielectric material for high frequency as 100 GHz Next, calculating and choosing microstrip line parameters considering technological constrains Additional possible modification that can be added

Duroid 5580 RT/duroid 5880Properties(typical Values) 2.2Dielectric constant Dissipation factor - Isotropic Uniform over volume Duroid 5580 manufactured by Rogers Corporation

Modeling the µstrip line The demand for Uniform EM field in the H«λ µstrip line “H” is the dielectric height, What is λ?

Modeling the µstrip line

Basic µstrip line Summing up basic µstrip line parameters:

Line modification Shielded microstrip line: +Reduces cross-talk +Significantly improves energy advancement through the µstrip line

Line modification Suspended microstrip +Foam-like material dielectric layer +dielectric constant close to unity +Much lower losses approximately 1:5 ratio - complicates manufacturing process

Losses Considerations Accurate losses equations are complicated, they’re explained in chapter 3 in the booklet Approximation:  Typical Duroid loss = 0.3 dB/λ  Microstrip length = 15 cm  λ(min) = 0.2 cm  Expected total losses = 22.5 dB This graph can be verified by SI simulations Internal Loss f[GHz]

Testing the µstrip line We need to measure the losses in the microstrip line in order to configure the equalizer or the pre-emphasis unit 100GHz pulses are hard to create, therefore we can calculate the Fourier series and deal with several lower frequencies individually This can be easily created using a simple signal generator

Testing the µstrip line A pulse signal can be split to a sum of sinusoidal signals in different frequencies by calculating its Fourier series example:

Testing the µstrip line Multiplying the signal to reach 100GHz frequency Running it through the microstrip line Using a mixer we decrease the frequency to a measuring level We repeat the process for additional various frequencies Enough points can give the losses vs. frequencies graph

Testing the µstrip line First schematic for 100GHz components :

Testing the µstrip line Second schematic for 50GHz components :

Testing the µstrip line Third schematic for 25GHz components :

Suitable Components EVA-ADF4350 is the supposed unit to generate a stable 0.5:4.4 GHz signal for the testing environment We deal with this unit as a black box with given parameters Other components can be found in our booklet appendix B

Conclusions & Next Steps Researching devices to sharpening the signal in unit-1, and additional units presented in the booklet Simulating the microstrip line using 3D simulation software such as “CST” Fabricating the design and testing it We’ve found various suitable devices that can operate in 100GHz frequency and more We have presented a HF medium in addition to testing environment