Low Noise Dc to DC Converters for the sLHC Experiments Low Noise Dc to DC Converters for the sLHC...
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Low Noise Dc to DC Converters for the sLHC Experiments Low Noise Dc to DC Converters for the sLHC Experiments TWEPP 2010 Aachen, Germany 21/9/2010 TWEPP
Low Noise Dc to DC Converters for the sLHC Experiments Low
Noise Dc to DC Converters for the sLHC Experiments TWEPP 2010
Aachen, Germany 21/9/2010 TWEPP 2010G. Blanchot, PH/ESE B.Allongue,
G.Blanchot, F.Faccio, C.Fuentes, S.Michelis, S.Orlandi CERN PH-ESE
1
Slide 2
Outline DCDC based powering scheme. DCDC development status.
Compatibility of DCDC with front-end systems. Noise optimized DCDC
Plug-in-Boards. Shielding and radiated magnetic field. Performance
of AMIS2-PIB using radtol ASIC. Performance of SM01B-PIB using
commercial chip. Conclusions. TWEPP 2010G. Blanchot, PH/ESE 2
Slide 3
TWEPP 2010G. Blanchot, PH/ESE Distribution scheme example
(ATLAS Short Strip concept) Identified integration issues: Radiated
magnetic field from stage 1 DC/DC. Board layout, coil topologies,
shields High noise susceptibility of modules. System tests with
hybrids Board area, material budget on stage 1 DC/DC. ASIC
development, compact layout. 10-12V 2 Converter stage2 on-chip
Detector Intermediate voltage bus(ses) Converter stage 1 block
Hybrid controller SC and optoelectronics 10-12V Module/Stave Scheme
based on 2 conversion stages: Stage 1: On Module Buck DC/DC Stage
2: On Chip Switched Capacitor Module 3
Slide 4
DCDC Development Status TWEPP 2010G. Blanchot, PH/ESE Critical
achievements: Radiation tolerant technologies have been selected.
Buck converter ASIC prototypes have been produced and tested Air
core inductors topology has been selected. Standard buck converter
prototypes have been produced, tested and used with systems.
Radiation tolerant buck converter prototypes using ASICs have been
produced. Critical achievements: Radiation tolerant technologies
have been selected. Buck converter ASIC prototypes have been
produced and tested Air core inductors topology has been selected.
Standard buck converter prototypes have been produced, tested and
used with systems. Radiation tolerant buck converter prototypes
using ASICs have been produced. Coils optimization 7 mm Package
QFN48 5 mm Package QFN32 7 mm Package QFN48 Radiation tolerant
ASICs AMIS2 IHP1 IHP2: DCDC Prototypes IHP Technology still under
development 4
Slide 5
Buck Converter TWEPP 2010G. Blanchot, PH/ESE Identification of
main noise sources: Switched voltage at node area N3 = Vin at
switch frequency + harmonics. On-time switching loop A = uprising
current. Off-time switching loop B = down-rising current.
Transition-time loop C = fast current transition inside switches.
Magnetic field emitted by the main coil L= triangular current.
These noise sources originate noise currents within the DCDC board
that in turn radiate fields along cables and interconnections.
Identification of main noise sources: Switched voltage at node area
N3 = Vin at switch frequency + harmonics. On-time switching loop A
= uprising current. Off-time switching loop B = down-rising
current. Transition-time loop C = fast current transition inside
switches. Magnetic field emitted by the main coil L= triangular
current. These noise sources originate noise currents within the
DCDC board that in turn radiate fields along cables and
interconnections. B A C 5
Slide 6
ISL6540 Proto2 Noise reduction in DC/DCs TWEPP 2010G. Blanchot,
PH/ESE DCDC optimization: Voltage nodes and current loop areas have
been reduced significantly. The subsequent reduction in radiated
noise results in reduction of conducted noise along cables. DCDC
optimization: Voltage nodes and current loop areas have been
reduced significantly. The subsequent reduction in radiated noise
results in reduction of conducted noise along cables. ISL6540
Proto3 ISL6540 Proto5 The noise level is characterized on a
reference test stand: The noise level is characterized on a
reference test stand: The noise level has been considerably reduced
on DCDC prototypes that used an Intersil ISL6540 controller and air
core coils. The noise level has been considerably reduced on DCDC
prototypes that used an Intersil ISL6540 controller and air core
coils. Very good performance was achieved in Proto5. Very good
performance was achieved in Proto5. Equally good performance was
achieved using the AMIS2 ASIC. Equally good performance was
achieved using the AMIS2 ASIC. This level of performance was
however not enough for the sensitive trackers front- end
electronics and detectors. This level of performance was however
not enough for the sensitive trackers front- end electronics and
detectors. AMIS2 QFN48 Test Board 6
Slide 7
Proto5 with UniGe Module TWEPP 2010G. Blanchot, PH/ESE Position
of hybrids Conducted noise test Radiated noise at corner Radiated
noise on top of hybrid Reference noise: ENC Average:560 ENC
Sigma:32 Measurements performed with the help of Sergio Gonzalez
from the University of Geneva. The susceptibility against radiated
fields of the UniGe module was measured using the Proto5 DCDC.
7
Slide 8
Proto5 on UniGe Module TWEPP 2010G. Blanchot, PH/ESE Conducted
noise test Radiated noise at corner Radiated noise on top of hybrid
Proto5, shielded coil: ENCSigma Proto5, shielded coil: ENCSigma
Reference: 560 32 Reference: 560 32 Conducted: 57133 Conducted:
57133 Radiated Corner: 58335 Radiated Corner: 58335 Radiated Top:
930176 Radiated Top: 930176 VCC and VDD powered from the same DCDC
converter, without regulator on VCC. The system is insensitive to
the conducted noise of the converters. High noise is observed when
the DCDC is very close of the hybrids: susceptibility to radiated
couplings. VCC and VDD powered from the same DCDC converter,
without regulator on VCC. The system is insensitive to the
conducted noise of the converters. High noise is observed when the
DCDC is very close of the hybrids: susceptibility to radiated
couplings. 8
Slide 9
Radiated fields susceptibility measured at Liverpool Shielded
3cm probe, 12 MHz, 6mA DCDC Edge Position Shielded DCDC Edge
Position Noise increases on all channels. Noise increases on all
channels. B field coupling only. B field coupling only. Noise
increases on all channels (all above 1000 electrons) due to B
field. Noise increases on all channels (all above 1000 electrons)
due to B field. Alternating pattern due to E field. Alternating
pattern due to E field. No global increase: B field is shielded. No
global increase: B field is shielded. Alternating pattern on two
first chips: some E field remains, probably due to leaking E field.
Alternating pattern on two first chips: some E field remains,
probably due to leaking E field. Noise Reference = 650 electrons
TWEPP 2010 G. Blanchot, PH/ESE Radiated fields need therefore to be
mitigated further on. 9
Slide 10
Noise Optimized Plug-in-Boards TWEPP 2010G. Blanchot, PH/ESE
New generation of DCDC plug-in board to be used with systems: A
form factor compatible with front-end systems under development
now. More compact design. Power interface: connector or bonds. In
some cases: control logic. Better control of the noise sources for
lower conducted and radiated couplings: Understanding of how
electromagnetic fields are emitted from power loops and switching
nodes. The reduction of radiated fields will result in reduced
conducted noise. Introduction of an electromagnetic shield: to
cancel E field couplings with front-end systems. to mitigate the
radiated B field down to compatible levels. A thermal interface
must be provided for cooling. New generation of DCDC plug-in board
to be used with systems: A form factor compatible with front-end
systems under development now. More compact design. Power
interface: connector or bonds. In some cases: control logic. Better
control of the noise sources for lower conducted and radiated
couplings: Understanding of how electromagnetic fields are emitted
from power loops and switching nodes. The reduction of radiated
fields will result in reduced conducted noise. Introduction of an
electromagnetic shield: to cancel E field couplings with front-end
systems. to mitigate the radiated B field down to compatible
levels. A thermal interface must be provided for cooling. 3
different DCDC-PIB have been designed and produced: AMIS2_DCDC: 2
versions with AMIS2 radiation tolerant ASIC, implementing noise
cancellation techniques. 10V down to 2.5V, rated for 2A. The noise
optimization method is explained by Cristian Fuentes at the Power
WG. SM01B: 1 version using a commercially available buck converter
chip similar to AMIS2 10V down to 2.5V rated 5A for the 0.25um ABCN
modules in use today. Another DCDC-PIB is under design for bonding
onto ATLAS Stavelets 3 different DCDC-PIB have been designed and
produced: AMIS2_DCDC: 2 versions with AMIS2 radiation tolerant
ASIC, implementing noise cancellation techniques. 10V down to 2.5V,
rated for 2A. The noise optimization method is explained by
Cristian Fuentes at the Power WG. SM01B: 1 version using a
commercially available buck converter chip similar to AMIS2 10V
down to 2.5V rated 5A for the 0.25um ABCN modules in use today.
Another DCDC-PIB is under design for bonding onto ATLAS Stavelets
10
Slide 11
Noise Optimized Plug-in-Boards TWEPP 2010G. Blanchot, PH/ESE
Enable Pgood Vin GND Vout PROTO5 AMIS2 SM01B Board size reduction
down to 26mmx13.5mmx9mm. Increased switching frequency: 2 MHz on
AMIS2, 3 MHz on SM01B. A custom coil has been developped with an
industrial partner : 250nH that will stand straight onto the AMIS2
ASIC. A custom shield is under development now: it aims to replace
the 200um copper foil boxes with Cu coated plastic cases to be
soldered directly onto the PCBs. Efficiencies above 80% achieved.
SM01B reaches 87% at 2A, and is still at 80% for 4A load current at
nominal input voltage. Board size reduction down to
26mmx13.5mmx9mm. Increased switching frequency: 2 MHz on AMIS2, 3
MHz on SM01B. A custom coil has been developped with an industrial
partner : 250nH that will stand straight onto the AMIS2 ASIC. A
custom shield is under development now: it aims to replace the
200um copper foil boxes with Cu coated plastic cases to be soldered
directly onto the PCBs. Efficiencies above 80% achieved. SM01B
reaches 87% at 2A, and is still at 80% for 4A load current at
nominal input voltage. SM01B 11
Slide 12
Shielding: Electric field TWEPP 2010G. Blanchot, PH/ESE B A C
CB A N3 FE ASIC Bondings Filters Coil Electric field coupling
Electric field shield Electric field is mainly radiated by node N3:
square wave of 10 V at switching frequency. The field couples on
the DC DC board filtered areas, on the output cables or traces and
on the FE bondings. The coupling is blocked very easily with the
addition of a shielding case that segregates the filtered areas
from the noisy areas on the DCDC board. A plastic box with a very
thin conductive layer is sufficient to provide E fied shielding.
The shield will reduce the conducted noise and also the couplings
in the bondings. Electric field is mainly radiated by node N3:
square wave of 10 V at switching frequency. The field couples on
the DC DC board filtered areas, on the output cables or traces and
on the FE bondings. The coupling is blocked very easily with the
addition of a shielding case that segregates the filtered areas
from the noisy areas on the DCDC board. A plastic box with a very
thin conductive layer is sufficient to provide E fied shielding.
The shield will reduce the conducted noise and also the couplings
in the bondings. 12
Slide 13
CB A N3 FE ASIC Bondings Filters Coil Shielding: Magnetic field
TWEPP 2010G. Blanchot, PH/ESE B A C Radiated Magnetic Field Coupled
Magnetic Field Radiated Magnetic Field Magnetic field is mainly
radiated by loops A and C and by the main coil L: triangular waves
of up to 8A peak to peak at switching frequency with different
emission spectrums for each loop. The field couples on the DC DC
board filtered areas, on the output cables or traces and on the FE
board. The coupling is mitigated with the addition of a shielding
case that segregates the filtered areas from the noisy areas on the
DCDC board. To be effective, eddy currents must develop in the
shield conductor material. At 2 MHz, = 50 m of copper. The
shielding effectiveness for Cu thickness from 10 m to 100 m will be
studied. The shield will reduce the conducted noise and also the
couplings in the FE board. Magnetic field is mainly radiated by
loops A and C and by the main coil L: triangular waves of up to 8A
peak to peak at switching frequency with different emission
spectrums for each loop. The field couples on the DC DC board
filtered areas, on the output cables or traces and on the FE board.
The coupling is mitigated with the addition of a shielding case
that segregates the filtered areas from the noisy areas on the DCDC
board. To be effective, eddy currents must develop in the shield
conductor material. At 2 MHz, = 50 m of copper. The shielding
effectiveness for Cu thickness from 10 m to 100 m will be studied.
The shield will reduce the conducted noise and also the couplings
in the FE board. 13
Slide 14
Radiated Magnetic Field TWEPP 2010 G. Blanchot, PH/ESE The
radiated magnetic field is measured along X, Y and Z axes with a
1cm loop probe over a grid. The vector magnitude is computed. 13 5
1 PROTO5 AMIS2 SM01B Switching freq. = 1 MHz Switching freq. = 1
MHz L = 350 nH L = 350 nH Load = 1A. Load = 1A. dBA/m]
[dBA/m]UnshieldedShieldedComment PROTO5115 Shielded coil only
SM01B>120