Proposal for Transmitter Linearity Specification (SNDR Method)grouper.ieee.org/groups/802/3/an/public/feb05/pagnanelli_1_0205.pdfState of SNDR Linearity Specification SNDR Specification

Proposal for Transmitter Linearity Proposal for Transmitter Linearity Specification (SNDR Method)Specification (SNDR Method)

Chris PagnanelliIEEE P803.2an Task ForceSanta Clara, February ’05

22/21/2005

OverviewOverview

Current State of SNDR SpecificationObjectivesPerformance Analysis ResultsProposed SpecificationConclusion

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State of SNDR Linearity Specification State of SNDR Linearity Specification

Transmitter Linearity Specification is Based on SNDR Measurements of Single-Tone and Two-Tone Test Signals

Overall measure of jitter, noise, and distortionPHY developers can optimally allocate transmitter impairmentsMeasurement accuracy maximized through use of precision analog measurement equipment (spectrum analyzers)

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State of SNDR Linearity Specification State of SNDR Linearity Specification

SNDR Specification Based on Frequency Dependent Requirement of the Form:

Specification allows distortion and noise to increase with increasing frequency High frequency noise and distortion has minimal channel capacity impactHigh frequency noise and distortion has major impact on analog circuit design complexity

( ) 25/log20B,Amin SNDR MHzf⋅−≥

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Objectives Objectives Base Transmitter Linearity Specification on Interoperability Requirements

Local receiver requirements are vendor discretionarySpecification must not preclude innovation in the area of distortion/noise cancellation

Base Transmitter Linearity Specification on Judicious Allocation of Implementation Loss

Optimal allocation is Not to require a perfect transmitter

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Performance Impact of TX SNDR Performance Impact of TX SNDR Basis for SNDR Performance Impact is Optimal DFE (Saltz) SNR

Cat6e Insertion Loss Model (100 meters)Class E Power Sum ANEXT Model100m Power Sum AFEXT Model at –41 dB Level1G ANEXT (coupling per Class E ANEXT model)Nominal TX Power (4.2 dBm, 5 MHz-450 MHz BW)-141 dBm/Hz Effective Receiver Noise

9-bit ADC (ENOB)-150 dBm/Hz background noise-147 dBm/Hz AFE noise (white)

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Typical Signal and Noise Spectra Typical Signal and Noise Spectra

Baseline Conditions for Optimal DFE Analysis

0 50 100 150 200 250 300 350 400-160

-150

-140

-130

-120

-110

-100

-90

-80Signal and Noise Spectra (Ptx=4.2dBm, L=100m)

PSD

(dB

m/H

z)

Frequency (Hz)

Optimal DFE SNR = 25.60 dB Rx SignalTotal Noise-48 dB txD Floor10G ANEXT10G AFEXT1G ANEXT-147 Rx Noise9.0b ADC Noise-150 Bkgd Noise

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Sensitivity of Intercept Parameter B Sensitivity of Intercept Parameter B

Increasing the Intercept Parameter beyond 58 dB has negligible SNR Margin benefit (<0.12 dB)

-70 -65 -60 -55 -50 -45 -40-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5

3SNR Margin vs. Intercept Parameter Value (B)

Intercept Parameter Value (dB)

SNR

Mar

gin

(dB

rel

ativ

e to

23.

3)

Floor Parameter (A) = 55 dBFloor Parameter (A) = 45 dB

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Sensitivity of Floor Parameter A Sensitivity of Floor Parameter A

Increasing the Floor Parameter beyond 48 dB has only marginal SNR Margin benefit (<0.33 dB)

-70 -65 -60 -55 -50 -45 -401.2

1.4

1.6

1.8

2

2.2

2.4

2.6

2.8SNR Margin vs. Floor Parameter Value (A)

Floor Parameter Value (dB)

SNR

Mar

gin

(dB

rel

ativ

e to

23.

3)

Intercept Parameter (B) = -58 dB

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Sensitivity of Sensitivity of Tx Tx Distortion v Rx Noise Distortion v Rx Noise

Improving Rx Noise yields greater SNR Margin benefit than improving Tx Distortion for Floor Parameter > 48 dB

-5 -4 -3 -2 -1 0 1 2 3 4 5-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6SNR Margin Sensitivity Analysis (TxD v RxN)

Relative Change (dB)

SNR

Mar

gin

(dB

)

TxD Floor relative to 48 dBRx Noise relative to 147 dBm/Hz

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Transmitter SNDR Specification Transmitter SNDR Specification

Base Specification on a Transmitter Linearity Requirement of

Maximum SNDR Limit of 48 dB Reached at Frequencies Below 79 MHz

SNDR measurements at ~41 MHz and ~79 MHz ensure that 48 dB SNDR maximum is reached Measurements at lower frequencies not required

( ) 25/log2058,48min SNDR MHzf⋅−≥

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Transmitter SNDR Specification Transmitter SNDR Specification 55.5.4 Transmitter signal to noise plus distortion

When in Test mode 4 and transmitting on a single pair into a 100Ωdifferential resistive load per the test configuration shown in Figure 55-22, the signal to noise plus distortion ratio of the differential signal at the MDI output shall be greater than the limit specified in Figure 55-x, which corresponds to:

Measurements of signal to noise plus distortion ratio shall be made with sinusoidal output waveforms (single-tone and two-tone).

( ) 4005,dB25/log2058,84min MHzMHz ≤≤⋅− ff

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Transmitter SNDR Specification Transmitter SNDR Specification 55.5.4 Transmitter signal to noise plus distortion (cont.)

0 50 100 150 200 250 300 350 40030

32

34

36

38

40

42

44

46

48

50Signal-to-Noise-Plus-Distortion v. Frequency Limit

Frequency (MHz)

SND

R (

dB)

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Transmitter SNDR Specification Transmitter SNDR Specification

55.5.4 Transmitter signal to noise plus distortion (cont.)

For sinusoidal measurements, the MDI shall be configured to output single-tone and two-tone waveforms at the frequencies specified for the six test cases given in Table 55-x, such that the peak-to-peak output of the sinusoidal signal corresponds to +16 with respect to a DSQ output signal. The measured signal to noise plus distortion ratio shall be greater than the values specified in Table 55-x. For two-tone waveforms, signal power shall be defined as the total (sum) power of both tones. Signal to noise plus distortion ratio measurements shall be made across a 5 MHz to 400 MHz band, using a resolution bandwidth of less than or equal to 100 kHz.

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Transmitter SNDR Specification Transmitter SNDR Specification Table 55-x: Signal to Noise Plus Distortion Requirements

Output Waveform Frequencies SNDR Specification (dB)

Single tone:

(53/1024)*800 MHz 48

(101/1024)*800 MHz 48

(167/1024)*800 MHz 44

Two tone:

(179/1024)*800 MHz, (181/1024)*800MHz 43

(277/1024)*800 MHz, (281/1024)*800MHz 39

(397/1024)*800 MHz, (401/1024)*800MHz 36

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Conclusion Conclusion

Proposed Transmitter SNDR Specification Meets Outlined Objectives for:

Compatibility with Interoperability RequirementsFrequency Dependency, and Judicious Allocation of Implementation Losses

Proposed Transmitter SNDR Specification is Based on Overall SNDR Requirement of

( ) 25/log2058,48min SNDR MHzf⋅−≥