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Getting faster bandwidth Getting faster bandwidth

Getting faster bandwidth - PowerPoint Presentation

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Getting faster bandwidth - PPT Presentation

HervéGrabas Getting faster bandwidth Hervé Grabas 1 Present bandwith status Limiting factors Cables Board Bonding wires Input line Sampling capacitance and switch Getting faster bandwidth Hervé Grabas ID: 590488

board bandwidth herv

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Slide1

Getting faster bandwidth

HervéGrabas

Getting faster bandwidth - Hervé Grabas

1Slide2

Present bandwith status

Limiting factors:CablesBoardBonding wiresInput line

Sampling capacitance and switch

Getting faster bandwidth - Hervé Grabas

2Slide3

Cable status

Getting faster bandwidth - Hervé Grabas

3

Safe to use cables under 30cm of length

Plot of the 3dB cutoff frequency of cable function of length Slide4

Board status

Getting faster bandwidth - Hervé Grabas

4

On board

measurment

with 3Ghz network

analyser

2Ghz bandwidth measured with network analyzerSlide5

Board + Chip status

Getting faster bandwidth - Hervé Grabas

5

500Mhz bandwidth measured with network analyzer

On board

measurment

with 3Ghz network

analyserSlide6

Board bandwith limitationGetting faster bandwidth - Hervé Grabas

6

Within the actual Psec3 tester board:

The signal goes through the 50Ohms to the chip

The signal returns via

gnd

on the board through all decoupling cap of all channels and the DAC.

The signal returns through the line to the connector

!

Decoupling cap shown here are on the board!Slide7

Board bandwidth fix

Getting faster bandwidth - Hervé Grabas

7

Future Psec3 tester board:

The signal goes through the 50Ohms to the chip

The DAC is RF shielded by an inductance

The signal returns via the per-channel dedicated return line (no ground)Slide8

Chip on board bandwidth issueGetting faster bandwidth - Hervé Grabas

8

Psec3

tester

board with chip:

The signal goes through the 50Ohms to the chip

Due to parasitic capacitive ground coupling in the chip the RF signals illuminate the whole chip

The signal returns via the

less inductive ground pads to the connector.Slide9

Chip on board fix

Getting faster bandwidth - Hervé Grabas

9

Psec3

tester

board with chip fixed:

The signal goes through the 50Ohms to the

chip

Losses are minimized by having a single specific return pathSlide10

Package bandwidth & fixGetting faster bandwidth - Hervé Grabas

10

With and without bonding wiresSlide11

Other bandwidth/losses issues?

Getting faster bandwidth - Hervé Grabas

11

Line dimension: .8µm×3072µm

Line resistance: 146 ohms

Input line

Return lineSlide12

Where are we limited in bandwidthsummary

Factors

DescriptionQuantization

FixThe measurement in itself (cables)

Total cable size<30Small cables, loss substraction and calibrationThe boardReturn

path grounded

2Ghz

Dedicated return path

The bonding wires of package

Bandpass

filter

Cutoff

freq

~

1Ghz

Flip

chip

The input line of the chip

Parasitic

capacitance and resistance

C ~ 1.5pF

R~ 150Ohms

Higher metal level

Getting faster bandwidth - Hervé Grabas

12