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Senior Design Expo 04/27/2012 1 Kenneth Corbett Endowment.

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Presentation on theme: "Senior Design Expo 04/27/2012 1 Kenneth Corbett Endowment."— Presentation transcript:

1 Senior Design Expo 04/27/ Kenneth Corbett Endowment

2  Design an optical communication Integrated Circuit (IC) chip that will allow full-duplex transmission of wireless data at a bandwidth of 100kbit/s over a distance of several meters using a Field Programmable Gate Array (FPGA) interface. 2

3  Undergraduate Seniors pursuing a B.S.E.E. 3 Markus Geiger Chris Goodale Pin-Jen Wang

4  Consulting Faculty 4 Dr. Ken NorenDr. Suat Ay

5  Product applications  Technical constraints and design goals  Simplified block diagram  General design considerations  Major design decisions  Integrated Circuit Design  FPGA interface  Final Product  Demonstration platform  Specifications  Project cost  Future work  References 5

6  Directional, highly secure wireless transmission  Control/monitor sensitive information/infrastructure eg. wireless traffic monitoring, wireless money transfer via cellphone, etc.  Alternative to WiFi (Wireless Fidelity), which is based on the IEEE standard  Electro Magnetic (EM) safe  Unregulated wireless spectrum  Wireless sensor networks 6

7  Transmitter (TX) requirements ▪ Pdp_max = 500mW ▪ V_bias = 1.5V (+/- 100mV)  Receiver (RX) requirements ▪ Pdp_typ = 100mW ▪ V_bias = -5V  Transmission distance through air ▪ limited by power output of light-emitting diode (LED) and beam half angle ▪ Power decreases through air with 7

8  Preliminary Specifications:  100kbit/s signal transmission  Range of 2+ meters  Custom transmission protocol  Total power dissipation of TX circuitry < 500mW  Total power dissipation of RX circuitry < 10mW  5V single-ended power supply 8

9 Light emitting element (transmitter) Photo sensitive element (receiver) user interface High gain trans impedance amplifier (TIA) Comparator to digitize the signal Decoder that processes binary input according to a communication standard Common Drain amplifier to provide sufficient current 9 Encoder that processes the received signal FPGA MCPnano Transceiver IC Free space User Receiver Transmitter

10  Off the shelf components  LED to transmit data (IR or visible light)  Photo-diode to receive data (PIN or Avalanche)  MCPnano Integrated Circuit (IC) Design  Amplifier / Comparator stages for the receiver circuit  Transmitter circuitry consisting of repeaters and FET  System integration/interface with FPGA  Connectivity/User-interface  Encoding/Decoding schemes 10

11 INFRARED (IR) LED VISIBLE LIGHT LED  Wavelength: 390nm to 780nm  Very susceptible to interference from ambient light (need for a versatile filter system & noise cancellation system)  May use solid-state lighting (more compact system, ease of deployment)  Wavelength: 780 nm to 950 nm  limits interference due to ambient light  Need for separate transmission circuitry  Vishay High Speed IR LED 890nm: 11

12 fff PHOTO TRANSISTOR PIN PHOTO-DIODE  Slow response time (~500ns+ rise & fall)  Not feasible for our com. System  Inherent gain of the NPN transistor  Low cost (50c/piece) AVALANCHE PHOTO-DIODE  Fast rise/fall times (5 to 50ns typ.)  5V typ. rev. bias  Low cost (eg. 50c/piece)  Osram Photo diode 900nm  Fast rise/fall times (1ns typ.)  Highly sensitive  High gain (self multiplication ‘avalanche’ mechanism)  40V typ. rev. bias  High cost ($50+/piece) 12

13 PIN PHOTODIODEIR LED 13

14  Design environment: Cadence  Process: ONSemi’s 0.5  m process (C5)  Tapeout Date: November 28 th, 2011  Cost:$960  IC Design Effort  Receiver design (TIA, comparator)  Transmitter design (LED driver) 14

15  Bias voltages to be set externally (adjustability)  Allows use of different diodes  Debugging  Feedback resistor/potentiometer located off chip  impractical to implement 5MOhm resistor on-chip  Flexibility, various distances possible  Reference current set through off-chip variable resistor (adjustable gain of opamp if needed) 15

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19  Custom VHDL code that implements the following protocol 19

20  Special Thanks to Dr. James Frenzel (aka Dr. J) for supplying us with two Digilent BASYS2 boards 20

21 21 backfront

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24  Specifications:  100kbit/s signal transmission  Maximum range of 3 meters  Custom transmission protocol (FPGA in VHDL)  Total power dissipation of TX < 500mW  Total power dissipation of RX < 10mW  5V single-ended power supply (battery pack) 24

25  Compact IC transceiver unit on a PCB  Datasheet/Documentation of transceiver  TX: LED  RX: Photo-diode  IC: TIA, Comparator, LED driver  Discrete level shifter  Custom Communication Protocol (VHDL) 25

26 Parts $ Fabrication and packaging – 20 parts (11/28/11) $ Poster for presentation $ Total cost $ 1,

27  Incorporate the transmission protocol (using shift registers, etc.) onto the Integrated Circuit  VHDL description may be used to create the layout using automated place & route tools  Improve the comparator design on the IC (accomplish hysteresis)  Design for higher speed transmission (500kbit/s +) 27

28  FSO applications / outlook into the future   IR vs. RF  https://www.audiolinks.com/articles/rfvsir/ https://www.audiolinks.com/articles/rfvsir/  Vishay High Speed IR LED 890nm:  d%3d d%3d  Osram Photo diode 900nm:  Z/?qs=K5ta8V%252bWhtarQtPwL45qKw%3d%3d Z/?qs=K5ta8V%252bWhtarQtPwL45qKw%3d%3d 28


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