QPLL Status – December 2004

Paulo Moreira

Paulo Moreira http://www.cern.ch/proj-qpll 2

PeopleS. Baron1

H. Furtado1,R. Haeni2,A. Marchioro1,P. Moreira1,J. Parsons3,S. dalla Piazza2

andS. Simion3

1) CERN,2) Micro Crystal 3) Nevis

Paulo Moreira http://www.cern.ch/proj-qpll 3

Outline• QPLL jitter problem

– Crystal activity dips– Power reduction network

• Circuit• Layout

• Irradiation tests• TTCrq

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QPLL Jitter Problem• August 2004:

– Stefan Simion found that at some frequencies an temperatures the QPLL jitter was largely exceeding the typical values.

• September 2004– Both Nevis and CERN worked quite hard at the problem but

all the hypotheses were either rejected or difficult to confirm.• October 2004

– With the help of Micro Crystal it was possible to confirm that the problem was due to activity dips in the crystal due to excessive power driving.

• October/November 2004– During this period work was done to find a simple and

effective way of reducing the power delivered to the crystal.

Paulo Moreira http://www.cern.ch/proj-qpll 5

-10 0 10 20 30 40 50 60 7040.074

40.075

40.076

40.077

40.078

40.079

40.08

40.081

40.082

40.083

40.084Excess Jitter Points for crystal xtal MC A

Temperature [C]

Freq

uenc

y [M

Hz]

Activity dips• Activity dips are due to

vibration modes that are mechanically coupled to the fundamental resonant mode.– The fundamental mode is a

thickness shear motion while modes causing activity dips are not.

– These modes can have frequencies quite close to the fundamental mode and are very dependent on temperature.

– They can thus interfere with the fundamental mode distorting the electrical characteristics of the crystal near the resonance.

Paulo Moreira http://www.cern.ch/proj-qpll 6

-10 0 10 20 30 40 50 60 7040.074

40.075

40.076

40.077

40.078

40.079

40.08

40.081

40.082

40.083

40.084Excess Jitter Points for crystal xtal super A MC

Temperature [C]

Freq

uenc

y [M

Hz]

Power reduction network

R1 = 62 , R2 = 240 , C = 10 nF

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Power reduction network

• Parasitic capacitance on “N1”:• Increases the power drive• Pulls the resonance frequency• Must be minimized

• As far as we can tell:• Activity dips are eliminated• QPLL jitter and centre frequency remain basically unchanged.

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Power reduction network - Layout

0805

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Irradiation Tests• Irradiation tests made in Boston by:

– Sefan Simion and John Parsons• Proton beam:

– Energy: 160 MeV– Fluence: 2.3 to 2.5 1013 p/cm2

• QPLL3• Quartz crystals:

– Micro Crystal– Conner Winfield

• (Accelerated aging tests being done at CERN)

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Irradiation

cw MC cw

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Irradiation

Jitter higher than what is measured normally in thelab due to experimental conditions and instruments used

cw MC cw

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TTCrq• New TTCrq on the drawing board

– Introduction of the power network– Pin J2 - 39 will become a +2.5 V power input

• For cards working in a radiation hard environment that can not use the internal 2.5 V regulator

• Optional 0 resistor for 100% compatibility with the previous version

– Optional 100 internal terminations for the LVDS signals