New Results on VDC-D2 and DORIC-D2 · VDC-D2 and DORIC-D2 work but with some deficiencies VDC-D2:...
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K.K. Gan ATLAS Pixel Week 1 New Results on VDC-D2 and DORIC-D2 K.K. Gan The Ohio State University February 13, 2001
Transcript of New Results on VDC-D2 and DORIC-D2 · VDC-D2 and DORIC-D2 work but with some deficiencies VDC-D2:...
K.K. Gan ATLAS Pixel Week 1
New Results onVDC-D2 and DORIC-D2
K.K. GanThe Ohio State University
February 13, 2001
K.K. Gan ATLAS Pixel Week 2
Outline
Introduction
Results on VDC-D2
Results on DORIC-D2
Plans
K.K. Gan ATLAS Pixel Week 3
VCSEL Driver Chip (VDC): convert LVDS signal into single-ended signal
appropriate to drive VCSEL Digital Opto-Receiver Integrated Circuit (DORIC):
decode clock and command signals from PIN diode
Introduction
K.K. Gan ATLAS Pixel Week 4
Ohio State University: Kregg Arms, K.K. Gan, Mark Johnson, Harris Kagan,
Richard Kass, Chuck Rush, Michael Zoeller
Siegen University: Michael Kraemer, Joachim Hausmann, Martin Holder,
Michal Ziolkowski
Opto-electronics Team
K.K. Gan ATLAS Pixel Week 5
Bright/Dim Currents of VDC-D2
two dice have dim currents < 1 mA
K.K. Gan ATLAS Pixel Week 6
Duty Cycle vs VCSEL Current
deviate significantly from 50% duty cycle for low VCSEL current
42
44
46
48
50
52
0 4 8 12 16
IVCSEL (mA)
Tunepad open = 1.25 V
Tunepad = 1.72 V
K.K. Gan ATLAS Pixel Week 7
42
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50
52
0 0.5 1 1.5 2
Iset (mA)
tunepad open = 1.25 Vtunepad = 1.72 V
Duty Cycle vs I_set Current
deviate significantly from 50% duty cycle for low I_set current can reduce deviation significantly with tune-pad connected
K.K. Gan ATLAS Pixel Week 8
Improvement in VDC-I
ideal design: dim current depends on tune-pad but not I_set VDC-D2: dim current depends on I_set due to
imperfect matching of currents in two transistors! submit two versions of VDC-I:
DMILL version and a version with bright current controlledby I_set added to dim current controlled by tune-pad
K.K. Gan ATLAS Pixel Week 9
VCSEL Current vs Tune-pad Current
20
10
0
I
(
mA
)V
CS
EL
amplitude of VCSEL current remains constantas tune-pad current is increased from 0 to 1 mA
K.K. Gan ATLAS Pixel Week 10
VCSEL Current vs I_set
dim current remains constantas I_set is increased from 0 to 2 mA
I
(
mA
)V
CS
EL
K.K. Gan ATLAS Pixel Week 11
DORIC-D2 with LVDS Reset at VDD (Default)
Input data
Decoded clock
Decoded data
K.K. Gan ATLAS Pixel Week 12
DORIC-D2 with LVDS Reset Grounded
Input data
Decoded clock
Decoded data
K.K. Gan ATLAS Pixel Week 13
BER/Crosstalk Measurement with DORIC and VDC
SCALER
40 MHzAsynchronous
CLOCK
XilinxXC4005SE CMOS
LVDS
CMOS LVDS
VDC
VDC
LVDS CMOS DORIC
VCSEL
VCSEL
PIN
Opto-package
Data Data
fiber o
ptic lin
k
K.K. Gan ATLAS Pixel Week 14
Binary Error Rate
DORIC-D2 has significantly more cross talk than DORIC-4A
placing DORIC-D2 in close proximity to PIN yields similar BER
10-10
10-8
10-6
10-4
10-2
100
10 20 30 40 50 60 70 80
BER
I PIN
(µA)
Packaged DORIC-D2Inner VCSEL on
Packaged DORIC-D2Inner VCSEL off
Packaged DORIC-4AInner VCSEL on
Packaged DORIC-4AInner VCSEL off
(90% CL)
DORIC-D2Opto-board
Truelight VCSEL
K.K. Gan ATLAS Pixel Week 15
observe spikes at edge-detector and pre-amp spy points pulsing test spy circuit induces a signal at LVDS ouputs floating and grounding guard-ring has no effect on pre-amp
back side silicon is highly resistive: ~ 1 MΩ
reduce to ~ 100 KΩ when scratched currently investigating possibility of grinding and metalizing
back side of bare dice
Investigation of Cross-talk
K.K. Gan ATLAS Pixel Week 16
600 mV different at pre-amp +/- spy point outputs pre-amp has low gain for small signal and output distorted pre-amp offset estimates to be a few mV has designed a dc feedback circuit for DORIC-I
simulation shows that it will fix offset problem need to include stray capacitance of traces in simulation
to verify that circuit will not oscillate
Pre-amp Offset
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Pre-amp with Feedback
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Pre-amp with Feedback
new
K.K. Gan ATLAS Pixel Week 19
Simulation of DORIC-D2 Pre-amp
no output signal for small input signal if there is an offset
K.K. Gan ATLAS Pixel Week 20
Simulation of DORIC-I Pre-ampDORIC-D2, zero offset
DORIC-I, zero offset
DORIC-I, 5 mV offset
DORIC-I, 10 mV offset
produce output signal similar to an pre-amp with no offset
K.K. Gan ATLAS Pixel Week 21
current consumption consistent with expectations 7-channel opto-board:
1.0 W @ 10 mA VCSEL current 1.4 W @ 20 mA VCSEL current
Power Consumption
0
5
10
15
20
25
I (m
A)
DORIC-D2 VDC-D2
VDD = 3.3 V
K.K. Gan ATLAS Pixel Week 22
VDC-D2 and DORIC-D2 work but with some deficiencies VDC-D2: some have low dim currents DORIC-D2:
some pre-amps have small offset cross-talks inside die
will emphasize irradiation of DORIC-D2 in April a new rad-hard bias circuit without
requiring a reset is needed for any DMILL submission
Plans
