EE194-EE290C. 28 nm SoC for IoT. Acknowledgement: Wayne Stark EE455 Lecture Notes, University of Michigan

Transcription

1 EE194-EE290C 28 nm SoC for IoT Acknowledgement: Wayne Stark EE455 Lecture Notes, University of Michigan

2 Course InformaKon Instructor: Dr. Osama Khan, Kris Pister Units: 4 Meets: TuTh 4-5:30 Cory 293 Pre-reqs: At least one of EE140, 142, 151 ; ( or equivalent) Office: Swarm Lab, Cory Hall, oukhan@berkeley.edu Office: 512 Cory Hall, ksjp@berkeley.edu Office Hours: TBD GSI: David Burne^ (db@berkeley.edu) GSI Office: Swarm Lab, EECS GSI Office Hours: TBD Discussion seckon: TBD

3 Lecture 1:Goals Know the difference between analog and digital communicakons Know the fundamental tradeoff between data rate, bandwidth, signal power and noise power in communicakng binary informakon (bits) from a source to a desknakon

4 EM Spectrum

5 US Radio Spectrum h^ps://

6 CommunicaKon System The goal of communicakon systems is to transfer informakon from one locakon to another at a distance away. Circuits, electromagnekcs, signal processing, microprocessors, and communicakon networks, Source: Wikipedia

7 CommunicaKon Range 1cm, 1m, 10m, 1Km, 10Km,, 20 billion Km,... An AU is just the distance from Earth to the Sun, about 93 million miles. h^p://voyager.jpl.nasa.gov/where/

8 CommunicaKon System Source Transmitted signal Received signal Transmitter Channel Receiver Destination Noise, interference, and distortion

9 Important Parameters The goal of communicakon systems is to transmit informakon from one locakon to another. This can be done in various ways which depends on certain resources. These include the energy, the noise, the channel condikons among others. Parameters: Power/Energy, Data Rate, Bandwidth, DistorKon, Bit Error Probability

10 Digital vs. Analog An analog message is a physical quankty that varies with Kme, Usually in a smooth and conknuous fashion. An analog communicakon system should deliver this waveform with a specified degree of fidelity. A digital message is an ordered sequence of symbols selected from a finite set of discrete elements. Since the informakon resides in discrete symbols, a digital communicakon system should deliver these symbols with a specified degree of accuracy in a specified amount of Kme.

11 ModulaKon ModulaKon involves two waveforms: A modulakng signal that represents the message. A carrier wave that suits the parkcular applicakon. A modulator systemakcally alters the carrier wave in correspondence with the variakons of the modulakng signal. The resulkng modulated wave thereby carries the message informakon. We generally require that modulakon be a reversible operakon, so the message can be retrieved by the complementary process of demodulakon.

12 ModulaKon h^p://

13 Why ModulaKon? Efficient Transmission: Efficient radiakon requires antennas whose physical dimension are at least 1/10 th of the signal s wavelength. Un-modulated transmission of an audio signal containing frequency components down to 100Hz would require antennas ~300 km long. Modulated transmission at 100MHz, as in FM broadcaskng, allows a prackcal antenna size of about one meter. Hardware limitakons Noise and interference Frequency assignments

14 Digital vs. Analog Digital communicakon differs from analog communicakon in that in a digital communicakon system during any finite Kme interval there is a finite number of possible transmi^ed waveforms. In an analog communicakon system during any finite Kme interval there are a potenkally infinite number of possible waveforms transmi^ed.

15 Digital vs. Analog h^p://blog.rfvenue.com/digital-wiireless-explored/

16 Digital vs. Analog In a digital communicakon system the receiver needs to decide, based on the received signal, which of the finite number of transmi^ed signals was sent. In an analog communicakon system the receiver needs to eskmate, based on the received signal, what was the transmi^ed signal. The performance measure for digital communicakon systems is usually the probability of making an error in deciding which waveform was transmi^ed.

17 Advantages of Digital Ease of regenerakon of signals in a series of regenerakve repeaters, The flexibility of circuitry available for processing digital signals (DSPs, VLSI), The ability to store informakon in digital format in various media (e.g. DVD, CD, RAM, Hard Disk), Many source are digital (e.g. data files).

18 Power Clearly the more power available the more reliable communicakon is possible. However, the goal is to reduce the required transmission power so that talk Kme is maximized. Power levels of radios vary from less than a milliwa^ to 1MWa^. Performance generally depends on the received power (not the transmit power) which depends on how far apart the transmi^er and receiver are located.

19 The goal is large data rates. Data Rate For a fixed amount of power as the data rate increases the energy transmi^ed per bit will decrease because of decreased transmission Kme for each bit. The data rate can be as low as several kbps to transmit speech to 10 s of Gbps for data.

20 Bandwidth The bandwidth is the amount of frequency spectrum available for use. Generally the FCC allocates spectrum and provides some type of mask for which the radios emissions must fall within. The larger the bandwidth the more independent fades across frequencies and thus be^er averaging is possible. The available bandwidth might be 3kHz for voice-band telephone lines and as high as 10 s of GHz.

21 DistorKon For analog sources such as speech or video the distorkon between the original source and the reproduckon of the original signal at the desknakon is open a performance measure of interest. The mean-squared error is one open used performance measure for distorkon.

22 Bit Error Probability Different sources require different error probabilikes (also call bit error rates). Bit error rates vary between 10 2 and 10 4

23 First Fundamental Tradeoff P Watts W Hz Source Whatever + Whatever Sink R bps AWGN with PSD N o /2

24 AssumpKons The source produces equally likely data bits (0s and 1s) at rate R bits/second. We transmit a signal (waveform) such that the received power is P. The transmi^ed signal has bandwidth W (Hz). Noise is added to the transmi^ed signal. The noise is white (power at all frequencies of interest), Gaussian and has power spectral density N0/2 Wa^s/Hz. This is called an addikve white Gaussian noise channel. We can allow any delay or complexity.

25 First Fundamental Tradeoff In 1948 Claude Shannon (U of M EE/Math graduate) published a paper in which he determined the tradeoff between data rate, bandwidth, signal power and noise power for reliable communicakons for an addikve white Gaussian noise channel. Let W be the bandwidth (in Hz), R be the data rate (in bits per second), P be the received signal power (in Wa^s), N 0 /2 the noise power spectral density (in Wa^s/Hz). Then reliable communicakon is possible provided R < W log 2 1+ P N o W

26 Capacity For large values of W the maximum rate (capacity) approaches lim W log 2 1+ P W N o W = P N o ln(2) = P N o Let E b be the energy transmi^ed per bit of informakon. Then E b = P R or P = E b R Using this relakon we can express the capacity formula as R W < log 2 1+ E b N o R W

27 Capacity R W < log 2 1+ E b N o R W InverKng this we obtain E b > 2 N o R W 1 R W

28 Capacity E b > 2 N o R W 1 R W Reliable communicakon is possible with bandwidth efficiency R/W provided that the signal-to-noise rako, E b /N o, is larger than the right hand side of the equakon. For small values of R/W the smallest value of E b /N o where reliable communicakon is Possible is ln(2)= That is, R 2 lim R W 0 W 1 R W = ln(2)

29 Capacity Eb/No(dB) Achievable 0 Not Achievable Rate (bps/hz)

30 10 1 Capacity Not Achievable High Energy, High Data Rate Bandwidth Limited Region Rate (bps/hz) 10 0 Achievable Low Energy, Low Data Rate Energy Limited Region Eb/No(dB) -1.59dB

31 db or not db? When the range of values for energy or power are vast we usually employ a db scale. The conversion is E b N o (db) =10 log 10 E b N o The smallest signal-to-noise rako for reliable communicakon (at low rates) is E b N o > log(2) = E b (db) >10 log10( 0.693) = 1.59dB N o

32 dbw, dbm SomeKmes absolute power levels are also expressed in db s by referencing them to either 1W or 1mW. When referencing to 1W the db units are wri^en as dbw. When referencing to 1mW the db units are wri^en as dbm. So, for example 100Watts =10 log 10 (100Watts /1Watt) = 20dBW =10log 10 ( 100Watts /1mWatt) = 50dBm 10Watts =10 log 10 (10Watts /1Watt) =10dBW =10 log 10 ( 10Watts /1mWatt) = 40dBm

33 dbw, dbm 1Watts =10log 10 (1Watts /1Watt) = 0dBW =10 log 10 ( 1Watts /1mWatt) = 30dBm 0.1Watts =10log 10 (0.1Watts /1Watt) = 10dBW =10 log 10 ( 0.1Watts /1mWatt) = 20dBm 0.01Watts =10 log 10 (0.01Watts /1Watt) = 20dBW =10log 10 ( 0.01Watts /1mWatt) =10dBm 0.001Watts =10log 10 (0.001Watts /1Watt) = 30dBW =10 log 10 ( 0.001Watts /1mWatt) = 0dBm

34 Notes The capacity formula only provides a tradeoff between energy efficiency and bandwidth efficiency. Complexity is essenkally infinite, as is delay. The model of the channel is rather benign in that no signal fading is assumed to occur. The capacity theorem says that we can communicate with error probability near zero at rates below the capacity or equivalently at values of E b /N 0 above a threshold.

35 Example Telephone modems use about 3000Hz and have P/No of 74dB. What rate is possible? P =10 N o = C = 3000 log / 3000 ( ) = 3000 log ( ) = kbps

36 Wireless ApplicaKons Paging Digital Cordless Phones Digital Cellular Packet Radio Wireless Local Area Networks Low Earth Orbit Satellites (e.g. GPS) Generally these systems are power or energy limited rather than bandwidth limited in that they must operate on ba^eries.

37 Wired ApplicaKons Telephone Modems DSL (Digital Subscriber Loop) Cable Modems Ethernet OpKcal Fiber Generally these systems are bandwidth limited rather than power or energy limited since they are typically powered from an AC power source.

38 Analog Cellular Analog cellular systems were in widespread use from the early 1980 s to the mid 1990 s. but are not being used anymore (in the US). All of these systems used FM (frequency modulakon) with FDMA (frequency division mulkple access).

39 Industrial ScienKfic and Medical(ISM) Bands Frequencies: MHz, MHz, MHz The data rates vary from around 10 kbps to 100 Mbps.

40 IEEE a,b,g,n,h WiMax UWB GPS LTE BLE IEEE Other wireless systems

41 SoC Block Diagram RF LO 2f o Gaussian Pulse Shaping Tx Data from RISC V I 2 Q Matching Network PA Dummy Complex Image Reject Filter Clock & Data Recovery Rx Data Clk To RISC V Passive IF IF Channel 1-bit Mixers Gain Gain Select Filter ADC Power Management Bandgap Vref Temp. sensor Timing Relaxation oscillator PTAT Iref LDO Power-on-Reset (POR) clock generation

42 Team FormaKon