0L[HG(cid:3)6LJQDO(cid:3)&LUFXLWV(cid:3)DQG(cid:3)6\VWHPV
`
`0RGHP(cid:3)7HFKQLTXHV(cid:3)(cid:16)(cid:3)(cid:27)(cid:3)(cid:16)(cid:3)
`
`(cid:3)(cid:3)
`
`
`The Modem as an example of a mixed signal system
`
`
`
`
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.1
`
`Dish
`Exhibit 1038, Page 1
`
`
`
`0RGHP(cid:3)7HFKQLTXHV(cid:3)(cid:16)(cid:3)(cid:27)(cid:3)(cid:16)(cid:3)
`
`(cid:3)(cid:3)
`
`
`The Modem as an example of a mixed signal system
`
`
`
`
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.1
`
`Dish
`Exhibit 1038, Page 1
`
`
`
`[’6/(cid:3)(cid:11)[[[(cid:3)’LJLWDO(cid:3)6XEVFULEHU(cid:3)/LQH(cid:12)(cid:3)2YHUYLHZ(cid:3)
`
`igh speed modem techniques for wired telephone connection
`
`(cid:3) H
`
` •
`
` High speed modems, CAP and DMT
`• DMT for ADSL (Asymmetrical Digital Subscriber Line)
`• Advantages of DMT over QAM and CAP
`• Main functions in digital processing
`• Circuit parts in the Analog Front End
`• G.lite, the low cost implementation of xDSL
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.2
`
`Dish
`Exhibit 1038, Page 2
`
`
`
`(cid:3)+LJK(cid:3)VSHHG(cid:3)PRGHPV(cid:15)(cid:3)&$3(cid:3)DQG(cid:3)’07(cid:3)
`
` •
`
` Modems with data streams of more than 128 kbit/s do not make use of the
`standard 64 kbit/s channels that are used for voice and ISDN
`• High speed modems are connected to dedicated modems in the Central
`Office that are directly linked to the digital network
`• Two types of modulation are used now, CAP (Carrierless Amplitude Phase
`modulation) and DMT (Discrete Multi Tone modulation)
`• In CAP amplitude and phase are modulated around a (suppressed) high
`frequency carrier with a high symbol rate. The digital data is mapped on a
`discrete number of amplitude and phase steps
`• In DMT the digital data are distributed over a high number (typically 128 to
`256) carriers. The symbol rate per carrier is low (4 kbaud) and the number of
`bits per symbol can be 15 in the most advanced systems.
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.3
`
`Dish
`Exhibit 1038, Page 3
`
`
`
`’07(cid:3)IRU(cid:3)$’6/(cid:3)(cid:11)$V\PPHWULFDO(cid:3)’LJLWDO(cid:3)6XEVFULEHU(cid:3)/LQH(cid:12)(cid:3)
`
` •
`
` 255 subcarriers, spacing 4.3125 kHz, 0 to 1.104 Mhz
`• Symbol rate per carrier 4 kHz, modulation between 0 and 15 bit per symbol
`• Maximum bitrate per carrier is 15 * 4k = 60 kbit/s.
`• QAM modulation, maximal 8 bit resolution (256 amplitude levels) on I
`vector and 7 bit resolution on Q vector
`• ADSL combined with POTS, first subcarrier in use on 25.875 kHz
`• ADSL mostly not used in duplex, lower frequencies for upstream data,
`higher frequencies for downstream data (Frequency Division)
`• Carrier 6 to 31 are used for upstream, carrier 16 is used for reference, carrier
`32 on nyquist frequency is not used for data
`• 25 carriers available for upstream, maximum theoretical bitrate of
`25*60 kbit = 1.5 Mbit, practical values between 64 and 640 kbit
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.4
`
`Dish
`Exhibit 1038, Page 4
`
`
`
`’07(cid:3)IRU(cid:3)$’6/(cid:3)(cid:16)(cid:3)FRQWLQXHG(cid:3)(cid:16)(cid:3)
`
`
`
`’07(cid:3)0RGXODWLRQ(cid:3)
`
`LPF
`
`HPF
`
`P OTS
`
`DMT
`
` 4k 26k 4.3125 subcarrier spacing 1.1M Hz
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.5
`
`Dish
`Exhibit 1038, Page 5
`
`
`
`’07(cid:3)IRU(cid:3)$’6/(cid:3)(cid:16)(cid:3)FRQWLQXHG(cid:3)(cid:16)(cid:3)
`
`(FKR(cid:3)&DQFHOODWLRQ(cid:3)
`
`POTS
`
`upstream
`
`)UHTXHQF\(cid:3)’LYLVLRQ(cid:3)PXOWLSOH[LQJ(cid:3)
`
`POTS
`
`upstream
`
`downstream
`
`downstream
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.6
`
`Dish
`Exhibit 1038, Page 6
`
`
`
`’07(cid:3)IRU(cid:3)$’6/(cid:3)(cid:16)(cid:3)FRQWLQXHG(cid:3)(cid:16)
`
`QAM constellation: 4 bits: 2 bit I and 2 bit Q
`
`615(cid:3)IRU(cid:3)%(5(cid:3) (cid:3)(cid:20)(cid:19)(cid:16)(cid:26)(cid:3)
`
`QAM constellation size
`
`Required SNR
`
`4 (QPSK)
`8
`
`
`16
`
`
`32
`
`
`64
`
`
`128
`
`256
`
`1024
`
`4096
`
`32768
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`14.5 dB
`19,3 dB
`21,5 dB
`24.5 dB
`27.7 dB
`30.6 dB
`33.8 dB
`39.8 dB
`45.8 dB
`54,8 dB
`
`Bits/symbol
`
`2(1,1)
`3(1,2)
`4(2,2)
`5(2,3)
`6(3,3)
`7(3,4)
`8(4,4)
`10(5,5)
`12(6,6)
`15(7,8)
`
`
`
`
`
`
`
`
`
`
`
`
`QAM constellation: 6 bits: 3 bit I and 3 bit Q
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.7
`
`Dish
`Exhibit 1038, Page 7
`
`
`
`’07(cid:3)IRU(cid:3)$’6/(cid:3)(cid:16)(cid:3)FRQWLQXHG(cid:3)(cid:16)(cid:3)
`
` •
`
` Carrier 33 to 255 are used for downstream, carrier 128 is used for reference,
`carrier 256 on nyquist frequency is not used for data
`• 222 carriers available for downstream, maximum theoretical bitrate of
`222*60 kbit = 13.32 Mbit, practical values between 4 and 8 Mbit
`• Line conditions tested during start-up, bitrate per carrier adjusted
`• In operation BER per carrier monitored, bits are shifted to other carriers if
`needed
`, for ADSL in dBm/100W
`• Signal levels for POTS in dBm/600W
`
`• Maximum signal level in Central Office is 20.4 dBm (3.31 Volt RMS, noise-
`like signal, peak to peak voltage is about 33 Volt)
`• Max. signal Remote Terminal 12.5 dBm. (1.33 Volt RMS, peak to peak
`voltage about 13 Volt)
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.8
`
`Dish
`Exhibit 1038, Page 8
`
`
`
`’07(cid:3)IRU(cid:3)$’6/(cid:3)(cid:16)(cid:3)FRQWLQXHG(cid:3)(cid:16)(cid:3)
`
`Channel Response
`
`RFI
`
`Bridged Tap
`
`Crosstalk
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.9
`
`Dish
`Exhibit 1038, Page 9
`
`
`
`’07(cid:3)IRU(cid:3)$’6/(cid:3)(cid:16)(cid:3)FRQWLQXHG(cid:3)(cid:16)(cid:3)
`
`Bits
`
`(cid:20)(cid:24)(cid:3)
`
`Attenuation
`
`Bits
`
`(cid:20)(cid:24)(cid:3)
`
`Frequency
`
`Frequency
`
`Frequency
`
`
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.10
`
`Dish
`Exhibit 1038, Page 10
`
`
`
`(cid:3)$GYDQWDJHV(cid:3)RI(cid:3)’07(cid:3)RYHU(cid:3)4$0(cid:3)DQG(cid:3)&$3(cid:3)
`
`DMT Discrete Multi Tone
`CAP Carrierless Amplitude Phase modulation
`QAM Quadrature Amplitude Modulation
`
`QAM and CAP mainly differ in the way they are generated:
`• CAP is in nature an ’analog’ quadrature implementation with a sine/cosine
`mixer
`• QAM is suited for time discrete digital implementation
`
`QAM and CAP have a high symbol rate on one carrier and therefore a wide
`side-band spectrum
`DMT has a low sybol rate (only 4k) and many carriers. Therefore is not very
`sensitive to ’spiky’ noise and RF interference. It can adapt easily to line
`conditions
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.11
`
`Dish
`Exhibit 1038, Page 11
`
`
`
`6LJQDO(cid:3)FRGLQJ(cid:3)LQ(cid:3)WKH(cid:3)WUDQVPLWWHU(cid:3)
`
` •
`
` Each 0.25 ms (4 kHz) a data frame is build taking data out of the ’elastic
`buffer’
`• After CRC encoding, scrambling, Reed Solomon encoding and interleaving,
`data frames are prepared for transmission
`• Tone ordering gives 256 complex vectors in the frequency domain (nr. of
`bits per tone and gain scaling depends on line conditions, the digital data are
`mapped on the QAM constellation)
`• With a 512 point IFFT a symbol of 512 time domain samples is created
`• The symbol of 512 samples is filled up with a 32 samples long cyclic prefix
`• After 68 data symbols a synchronization symbol with a nominal length of
`544 samples is added making a superframe of 17 ms
`• Samplerate is 544*69/17ms = 2.208 Msamples/s = 256 * 4.3125 ksamples/s
`• The 2.208 Msamples/s output signal can be bandlimited in 1.104 MHz
`analog frquency band. An oversampled DA is preferred for smooth
`interpolation
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.12
`
`Dish
`Exhibit 1038, Page 12
`
`
`
`0DLQ(cid:3)IXQFWLRQV(cid:3)LQ(cid:3)GLJLWDO(cid:3)SURFHVVLQJ(cid:3)(cid:11)UHFHLYHU(cid:12)(cid:3)
`
`In the receiver most digital operations are reverse to the operations in the
`transmitter. A function that is unique for the receiver is the time equalization
`which is necessary to compensate for the dispersion and reflection in the line:
` The telephone line (local loop) is at most 5.5 km long
`• Propagation delay is about 30 m s with a dispersion of a few m s.
`• The sampling must be synchronized to the 2.208 MHz sample frequency of
`the transmitter. 4.416 MHz is commonly used as frequency in the DSP
`• Each symbol consists of 512 samples plus the 32 samples ‘cyclic prefix’.
`This prefix is needed to avoid intersymbol interference or leakage
`• Leakage between symbols can originate from the different delays for
`different frequencies in the band from 0 to 1.104 MHz
`• A 160 tap adaptive FIR filter on 4.416 MHz (36 m s) is used for equalization
`
` •
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.13
`
`Dish
`Exhibit 1038, Page 13
`
`
`
`:KDW(cid:3)GRHV(cid:3)$’6/(cid:3)ORRN(cid:3)OLNH(cid:3)LQ(cid:3)WKH(cid:3)WLPH(cid:3)DQG(cid:3)IUHTXHQF\(cid:3)GRPDLQ(cid:3)
`
`(cid:19)(cid:19)
`
`(cid:19)(cid:20)
`
`(cid:20)(cid:19)
`
`(cid:20)(cid:20)
`
`Carrier ‘2’
`
`I(cid:20)
`
`I(cid:21)
`
`I(cid:22)
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.14
`
`Dish
`Exhibit 1038, Page 14
`
`
`
`$’6/(cid:3)LQ(cid:3)WKH(cid:3)WLPH(cid:3)GRPDLQ(cid:3)
`
` •
`
` Each symbol consist of 512 samples in the time domain that represents the
`summation of the 256 carrier signals and 32 ‘cyclic prefix’ samples
`• Carrier n (on n*4.3125 kHz) is exactly n periods long in the time period of(cid:3)
`512 samples(cid:3)
`• Leakage from other symbols is avoided by the ‘cyclic prefix’ (guardband) of
`32 samples(cid:3)
`• When a FFT over 512 samples is executed some energy of the ‘cyclic prefix’
`may leak into the frequency domain, giving only a small ‘noise like’
`addition to the frequency spectrum(cid:3)
`• Complex frequency vectors can be recovered with almost no leakage.
`Amplitude and phase of the vectors must be corrected for equalization and
`dispersion(cid:3)
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.15
`
`Dish
`Exhibit 1038, Page 15
`
`
`
`&KDUDFWHULVWLF(cid:3)RI(cid:3)WKH(cid:3)$’6/(cid:3)VLJQDO(cid:3)
`
` •
`
` DMT is a multi carrier technique: Distortion of one carrier is ’unwanted
`signal’ in another carrier
`• For the maximum resolution of 15 bits/symbol and a BER = 10 -7, a SNR of
`55 dB is needed on one carrier (maximum Vpp = 1 or VRMS = 0.35)
`• Mean carrier amplitude is VRMS,mean = 0.58*0.35 = 0.20
`• About 250 carriers contribute to the total power resulting in a RMS
`=
`20.0
`250
`23.3
` for the ADSL signal
`amplitude value of
`• Clipping must be less then 10-7 so the peak amplitude is about 5 times higher
`=
`=
`9
`23.310
`3.32
`
`than the RMS value resulting in
`33
`,
`max
`• The (white) noise over the full 1.1 MHz bandwidth must be lower then
`
`
`+ -=- (cid:247)ł(cid:246)(cid:231)Ł(cid:230)
`G%
`G%
` relative to Vpp = 1
`55
`log
`10
`256
`31
`• Maximum amplitude 32.3 = 30 dB, so the minimum S/N ratio is 61 dB
`• All components in the analog chain must have noise and distortion much
`lower than -61 dB
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.16
`
`Dish
`Exhibit 1038, Page 16
`
`(cid:215)
`(cid:215)
`
`
`&LUFXLW(cid:3)SDUWV(cid:3)LQ(cid:3)WKH(cid:3)$QDORJ(cid:3))URQW(cid:3)(QG(cid:3)(cid:3)
`
`There are many circuits parts in the total signal chain:
`
` •
`
` DA converter
`• Transmitter
`• Splitter filter
`• Transformer and hybrid
`• 7HOHSKRQH(cid:3)OLQH(cid:3)
`• Transformer and hybrid
`• Splitter filter
`• Receiver and gain control
`• AD converter
`
`To maintain optimum signal quality all components in the chain must have a
`THD plus noise much lower than -70 dB. The SINAD of the convertors must
`be 12 to 13 bit
`
`
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.17
`
`Dish
`Exhibit 1038, Page 17
`
`
`
`*(cid:17)OLWH(cid:15)(cid:3)WKH(cid:3)ORZ(cid:3)FRVW(cid:3)LPSOHPHQWDWLRQ(cid:3)RI(cid:3)[’6/(cid:3)
`
`G.lite is named to the ITU specification for a xDSL protocol that compared to
`ADSL has:
`
` •
`
` Low cost but still offering up to 128 kbit upstream and 1.5 Mbit downstream
`• Better compatability to POTS, no splitter filter needed
`• Suitable as a very fast PC ’telephone line’ modem that can compete with
`cable modems
`
`
`G.lite is also a DMT technique with:
`
` •
`
` 127 carriers covering a frequency band from 0 to 552 kHz
`• A constellation diagram 8 (4,4) with a maximum size of 256
`• Level adaption to prevent distortion on the line and interference with POTS
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.18
`
`Dish
`Exhibit 1038, Page 18
`
`
`
`&KDUDFWHULVWLF(cid:3)RI(cid:3)WKH(cid:3)*(cid:17)OLWH(cid:3)$)((cid:3)DW(cid:3)VXEVFULEHU(cid:3)VLWH(cid:3)
`• For the maximum resolution of 8 bits/symbol and a BER = 10 -7, a SNR of
`34 dB is needed on one carrier (maximum Vpp = 1 or VRMS = 0.35)
`• Mean carrier amplitude is VRMS,mean = 0.58*0.35 = 0.20
`• About 125 carriers contribute to the total power resulting in a RMS
`=
`20.0
`125
`28.2
`amplitude value of
` for the ADSL signal
`• Clipping must be less then 10-7 so the peak amplitude is about 5 times higher
`=
`=
`9
`28.210
`8.22
`
`than the RMS value resulting in
`33
`,
`max
`• The (white) noise over the full 1.1 MHz bandwidth must be lower then
`
`G%+
`-=
`G%
`34
` )128log(
`10
`
`13
` relative to Vpp = 1
`• Maximum amplitude 22.8 = 27 dB, so the minimum S/N ratio is 40 dB
`• All components in the analog chain must have noise and distortion much
`lower than – 40 dB
`
`
`
`Mixed Signal Circuits and Systems, A.J.M. van Tuijl, IC Ontwerpkunde, sheet 8.19
`
`Dish
`Exhibit 1038, Page 19
`
`(cid:215)
`(cid:215)
`(cid:215)
`-
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