Lec. 1: Introduction to Data Convertors

Transcription

1 In The Name of Almighty Lec. 1: Introduction to Data Convertors Lecturer: Hooman Farkhani Department of Electrical Engineering Islamic Azad University of Najafabad Feb

2 Assignments Homework: (15%) Midterm Project: (25%) Transistor level design and simulation of a data converter subblock (no layout) Prepare a project report in the format and style of an IEEE jour nal paper Final Exam (60%) 2

3 Tools and Technology Primary tools HSPICE 2011 or later Cadence Virtuoso Schematic Editor with 0.18-μm model embe dded You can use your own tools/setups at own risk Getting started Read tutorials and setup info provided in HSPICE help Technology 0.18-μm TSMC CMOS model 3

4 Reference Books M. Pelgrom, Analog-to-Digital Conversion, Springer, Gustavsson, Wikner, Tan, CMOS Data Converters for Commu nications, Kluwer, A. Rodriguez-Vazquez, F. Medeiro, and E. Janssens, CMOS T elecom Data Converters, Kluwer Academic Publishers, W. Kester, The Data Conversion Handbook, Newnes, B. Razavi, Data Conversion System Design, IEEE Press, R. Schreier, G. Temes, Understanding Delta-Sigma Data Conv erters, Wiley-IEEE Press, R. v. d. Plassche, CMOS Integrated Analog-to-Digital and Dig ital-to-analog Converters, 2nd ed., Kluwer, J. G. Proakis, and D. G. Manolakis, Digital Signal Processing, Prentice Hall,

5 An Analog Word Everything in the physical world is an analog signal i.e.: They are continuos and can take an inifinity of values Sound, light, temperature, gravitational force x(t) Need to convert into electrical signals Transducers: converts one type of energy to another Examples Electro-mechanical, Photonic, Electrical, Microphone/speaker Thermocouples Accelerometers t 5

6 An Analog Word Transducers Allow us to convert physical phenomena to a voltage potential in a welldefined way. 6

7 Data Converters: مبدل های داده - Analog to Digital Converter (ADC) - Digital to Analog Converter (DAC) 7

8 Data Converter Applications (1) Consumer Electronics - Audio, TV, Video - Digital Cameras - Automotive control - Appliances - Toys - Sensors/instrumentation Communications - Mobile phones - Personal Data Assistants - Wireless Transceivers/ Wireline Communication - Routers, Modems -. 8

9 Example (1) A typical cell phone contains: - 4 Rx ADCs - 4 Tx DACs Dual Standard. I/Q - 3 Auxiliary ADCs - 8 Auxiliary DACs Audio, Tx/Rx power control, Battery charge control, display A total of 19 data converters! 9

10 Basics: Analog-to-Digital Conversion Conversion Process: - 3 steps: Sampling Quantification Coding These operations are all performed in a same element: The A to D Converter 10

11 1. Sampling in Time: Digital system works with discrete states The signal is only defined at determined times The sampling times are proportional to the sampling period (T s ) T s x(t) x s (t) x(t) x s (t=k*t s ) Question 1: How fast can we sample the analog signal? (Sampling Rate) - Do a research on Nyquist sampling-rate ADCs. T s 11

12 2. Quantification The signal can only take determined values Belonging to a range of conversion (ΔV r ) Based on number of bit combinations that the converter can output Number of possible states: N=2 n where n is number of bits Resolution: Q= ΔV r /N x q (t) Q ΔVr T s t 12

13 2. Quantification (Cont.) Example: Assume that Analog signal varies from 0 to 1.8V. We want to digitize the input by 3 digits. Thus we have resolution=q =1.8/2^3 =225mV For 6-bit ADC: Q=1.8/2^6=28mV. For 8-bit ADC: Q=1.8/2^8=3mV. 13

14 3. Coding Assigning a unique digital word to each sample Matching the digital word to the input signal A Discretization Analog Input Voltage Digitalization Step Width (1 VLSB) V j+1 V j T[1] T[2] T[3] T[4] T[5] T[6] T[n] Digital Output Code

15 ADCs for different applications: Medium Resolution; High-Speed ADCs (Gigabit Ethernet, Fas t Ethernet) 6-7 bit 250Msps, 7-8 bit 125Msps High Resolution; Medium-Speed ADCs (xdsl) bit 35Msps; Low Power (VDSL) Medium-to-High Resolution; Medium-to-High BW ADCs (zero-if Receivers: , WiMAX) bit 80Msps Large DR; Highly Linear; Medium-to-High BW ADCs (IF Sampling, Multi-Standard: Software Radio Architectures) bit Msps; SFDR > 90dB 15

16 ADCs for different applications (cont.): High Resolution Audio/Voice BW ADCs (CD/DVD Quality) - 24 bit 192Ksps; Low Noise, Large DR Medium-to-High Resolution; Medium-to-High BW ADCs (Im aging & Video Processing: Imaging Devices, HDTV) bit 40Msps, Low Power for Portables Question(2): For some especial applications, find the required resolution and sampling rates of ADCs. Question(3): Do a brief research on history of ADCs/ DACs from 1950 till now. 16

17 ADC Landscape in

18 ADC Landscape in 2012 ADCs have become substantially greener over the years 18

19 ADC landscape

20 Figure-of-Merit (FOM) versus frequency of operation 20

21 Reference Books M. Pelgrom, Analog-to-Digital Conversion, Springer, Gustavsson, Wikner, Tan, CMOS Data Converters for Commu nications, Kluwer, A. Rodriguez-Vazquez, F. Medeiro and E. Janssens, CMOS T elecom Data Converters, Kluwer Academic Publishers, B. Razavi, Data Conversion system design, IEEE pres, R. V. d. Plassche, CMOS Integrated Analog-to-Digital and Di gital-to-analog Converters, 2 nd ed., Kluwer, W. Kester, The Data Conversion Handbook, Newnes, J. G. Proakis and D. G. Manolakis, Digital Signal Processing, Prentice hall,

22 References Professor Boris Murmann Course slides 2013, Stanford University- EE315B course Dr. Reza Lotfi, ADC course slides