Proposed 8GFC Specsfor EMI Reduction

Mike JenkinsLSI Logic

6 Aug 2007

T11/07-436v0

Proposed Modified or Additional Specifications to

Control EMI• Differential to Common Mode Conversion

(SCD11 & SCD22)– Constrains CM voltage generated from

differential signal– Similar to “Impedance Balance” in SATA spec

• TX Common Mode Voltage– Convert from single RMS or peak voltage to a

limit across frequency spectrum

• See http://www.t10.org/ftp/t10/document.07/07-007r2.pdf

for same specs as adopted by 6 Gb/s SAS

6 Aug 2007

T11/07-436v0

Proposed Format of SpecsMeasured Value < max [ L, min [ H, N + 13.3 log10(F/4.25GHz) ] ]

50 MHz < F < 8.5 GHz

-40

-30

-20

-10

0

10

20

0.1 1 10

L

NH

H: Max value (high frequency asymptote)

L: Min value (low frequency asymptote)

N: Value at Nyquist frequency (4.25 GHz)

6 Aug 2007

T11/07-436v0

FCC Radiated Emissions Limits(relative to 1uV/meter)

Radiated Emissions Limits

Frequency (MHz)

Field Strength (microvolts/meter

Measured Distance (meters)

0.009-0.490

2400/F(kHz)

300

0.490-1.705

24000/F(k Hz)

30

1.705-30.0

30 30

30-88 100 3

88-216 150 3

216-960 200 3

Above 960

500 3

30 100 40.0 90 39.1 20 3588 100 40.0 90 39.1 2000 61.6688 150 43.5 150 43.5

216 150 43.5 150 43.5216 200 46.0 210 46.4960 200 46.0 210 46.4960 500 54.0 300 49.5

8500 500 54.0 300 49.5

30

35

40

45

50

55

60

10 100 1000 10000

MHz

dB

Class B limit13.3 dB/decClass A limit

Mechanism for converting common

mode noise into EMI is unknown, but EMI is

assumed to be proportional to the noise

that causes it.

Hence, limit curve for each parameter (in dB) should reasonably track these Radiated Emission

limits.

6 Aug 2007

T11/07-436v0

Proposed TX CM Voltage Limit ( L = 12.7 dBmV(rms), N = 28 dBmV(rms) )

0.1 12.7 -31.30.3 12.7 -31.330 39.3 -4.7

Vcm Maxim um

10

15

20

25

30

0.1 1 10

GHz

dB

mV

(rm

s)

-34

-29

-24

-19

-14

dB

m (

25W

re

f)

6 Aug 2007

T11/07-436v0

S-parameter Single-ended to Mixed Mode Conversion

S11 - S13 - S31 + S33 S12 - S14 - S32 + S34 S11 + S13 - S31 - S33 S12 + S14 - S32 - S34

S21 - S23 - S41 + S43 S22 - S24 - S42 + S44 S21 + S23 - S41 - S43 S22 + S24 - S42 - S44

S11 - S13 + S31 - S33 S12 - S14 + S32 - S34 S11 + S13 + S31 + S33 S12 + S14 + S32 + S34

S21 - S23 + S41 - S43 S22 - S24 + S42 - S44 S21 + S23 + S41 + S43 S22 + S24 + S42 + S44

SDD11

SCC11

SDC11

SCD11

1

2Smm =

Note: S13 = S31 (reciprocal),

so

SDC11 = SCD11 = (S11–

S33)/2

For derivation of conversion to mixed mode parameters, see (for example):http://www.simtech.a-star.edu.sg/Research/TechnicalReports/TR04JT03.pdf

6 Aug 2007

T11/07-436v0

Proposed SCD11, SCD22 Limit(L = -26dB, N = -10.7dB)

TOLp 0.03 Cp: 0.94 pFTOLn 0 Cn: 0.7 pF

Zo(kW): 0.05 skew: 5 ps -15

GHz S11 S22 SCD110.01 1.000628515964150.06 3E-002-3.04169000720564E-003i2.03+3.04169000720564E-003i1.47760468382431E-002-1.5205094390244E-003i-36.56 -2.19911485751286E-003i2+2.19911485751286E-003i-1.20902507739005E-006-1.09955609936392E-003i-59.18 ###0.10 1.006302965922710.63 3E-002-3.04169000720564E-002i2.03+3.04169000720564E-002i1.45505472593495E-002-1.52017155734176E-002i-33.54 -2.19911485751286E-002i2+2.19911485751286E-002i-1.20888038228697E-004-1.09942450541595E-002i-39.18 ###0.20 1.012645659224831.26 3E-002-6.08338001441128E-002i2.03+6.08338001441128E-002i1.3867826781254E-002-3.03829717965304E-002i-29.53 -4.39822971502571E-002i2+4.39822971502571E-002i-4.8337684947761E-004-2.19805185630139E-002i-33.16 ###0.50 1.031914615312213.14 3E-002-0.152084500360282i2.03+0.152084500360282i9.11439046719627E-003-7.56013093007754E-002i-22.37 -0.109955742875643i2+0.109955742875643i-3.01345797117933E-003-5.48121979328987E-002i-25.21 ###1.00 1.064847773294956.28 3E-002-0.304169000720564i2.03+0.304169000720564i-7.50430532610079E-003-0.148712523974592i-16.54 -0.219911485751286i2+0.219911485751286i-1.19458370510655E-002-0.108642229488422i-19.23 ###2.00 1.1339007802912112.57 3E-002-0.608338001441128i2.03+0.608338001441128i-6.88436509802333E-002-0.279043247483696i-10.83 -0.439822971502571i2+0.439822971502571i-4.61301581471641E-002-0.209766934135201i-13.36 ###5.00 1.3691077706248531.42 3E-002-1.52084500360282i2.03+1.52084500360282i-0.35003344662781-0.486945017342385i-4.44 -1.09955742875643i2+1.09955742875643i-0.232102203751601-0.422173863195309i-6.34 ###

10.00 1.8744560875853462.83 3E-002-3.04169000720564i2.03+3.04169000720564i-0.687290107653814-0.468554953056033i-1.60 -2.19911485751286i2+2.19911485751286i-0.547311912154629-0.497756549899921i-2.62 ###

SATA TXSATA RX30 0.03 100 0 -15 150 0.15 -30 -3088 0.088 100 0 -15 300 0.3 -30 -3088 0.088 150 3.5 -11.5 300 0.3 -20 -30

216 0.216 150 3.5 -11.5 600 0.6 -20 -30216 0.216 200 6 -9 600 0.6 -10 -20960 0.96 200 6 -9 1200 1.2 -10 -20960 0.96 500 14 -1 1200 1.2 -10 -10

8500 8.5 500 14 -1 2400 2.4 -10 -102400 2.4 -4 -4

30 0.03 90 -15.92 5000 5 -4 -4

-40

-30

-20

-10

0

0.01 0.10 1.00 10.00

GHz

dB

S11

S22

SCD11

FCC A & B

SATA TX

SATA RX

SCD11 Limit

+Input(port 1)

-Input(port 2)

CP

Cn Rn

RP

RP = Zo x (1+TOLP)

Rn = Zo x (1+TOLn)

Additional skew added to

+Input

delayskew

6 Aug 2007

T11/07-436v0

A Note about Impedance Scaling in Mixed Mode

ConversionFor scattering parameters, the incident & reflected ‘power waves’

are defined as V+/sqrt(Zref+) and V-/sqrt(Zref-), respectively,

where Zref+ is the reference impedance of the incident wave

and Zref- is the reference impedance of the reflected wave.

In mixed mode parameters, these impedances can be different. Hence, a differential input voltage of 1200mVpp encountering the proposed limit SCD11 of -10.7dB = 0.292 at the Nyquist frequency results in a reflected common mode voltage of:

Vcm = 1200mVpp x 0.292 x sqrt[25W/100W] =

175.2mVpp.

This limit compares reasonably with the proposed +28dBmV(rms) common mode TX voltage limit, equivalent to 25mV(rms) = 70.7mVpp.

ref: http://en.wikipedia.org/wiki/S-parameters

6 Aug 2007

T11/07-436v0

Summary

• A spec format is proposed to limit AC common mode voltage in 800-DF-EL-S– Spectral limit line– Limits single-tone 4.25GHz Vcm to

25mV(rms)

• Limits for SCD11 & SCD22 also proposed to control EMI