fehlerbehebung am fertigen asic chip möglichkeiten der
TRANSCRIPT
5. März 2007, DarmstadtEE-Gruppenmeeting
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Möglichkeiten der Fehlersuche / Fehlerbehebung am fertigen ASIC Chip
am Beispiel des Beetle readout chip
Sven LöchnerGSI Darmstadt
former: MPI for Nuclear Physics, Heidelberg
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Agenda
“Unsightly” behaviours - patches and workaround
• UV-Laser patch• Sticky Charge• 80 MHz Crosstalk• Readout Baseline Variation
• Focused Ion Beam (FIB) patch• Tristate-Patch• Signal Swap
Beetle 1.3 on a test PCB
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Sticky Charge: Problem
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Sticky Charge: Simulation
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Sticky Charge: Layout
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Sticky Charge: Laser opening
Laser: (UV mode)
remove of passivation (Oxide, Nitride, Polyimide)
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Sticky Charge: Timing shift
Probe needle test with positive and negative phase shift of reset signal ROAmpReset
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Sticky Charge: New timing
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
80 MHz X-talk: Problem
Cross talk with a frequency spectrum of 80 MHz present on:
• Digital signals, e.g. DataValid• Analogue signals, e.g. AnalogOut• Power supply lines: Vddd, Vdda
Comparison: Beetle 1.1 Beetle 1.2# Flip-flops 1349 3043# Clock buffers 21 284Guard ring logic analogue digital
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
80 MHz X-talk: Idea & Layout (1)
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
80 MHz X-talk: Layout (2)
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
80 MHz X-talk: Laser patch
35 µ
m
50 µm
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
80 MHz X-talk: Pictures
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
80 MHz X-talk: Comparison
before patch after patch
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Readout Baseline Variation
Observation:shaper bias current affects amplitude of baseline variation
Laser patch:probing shaper power supply at different channels
Difference in Vddbetween ch. 0 and ch. 127: 24 mV
between ch. 0 and ch. 63: 210 mV
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Tristate: problem
Normally: end of prototype chip testing
• Problems with first prototype readout chip Beetle 1.0• Internal data bus between I²C-interface and registers is always zero
=> all setup and DAC registers are zero => Chip isn’t programmable
• Reason for data bus problem:• A bug in the extraction rules causes that a diffusion shortcut in a tristate
layout wasn’t seen in the LVS check as an error
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Tristate: wrong layout
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Tristate: simulation
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Tristate: new layout
• Diffusion of PMOS separated from Vdd
• Diffusion of NMOS separated from Gnd
• Additional guard ring around NMOS
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Tristate: way out?
Way out of the Beetle 1.0 prototype problem?
• Tristate patch with a Focused Ion Beam (FIB)• All register should be programmable• Read out of register settings via I²C is not possible
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Tristate: FIB patch
• 1 cut• 9 interconnections
Chip was programmable !!!
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Readout header: parity bit
• Parity bit (I1) is wrong encoded in 4 port mode and Rclk divider = 0 (LHCb mode)
all other modes or Rclk divider settings�Parity bit is OK
• problem is understood in verilog• not so easy to fix• simple workaround: swap position I1 with I5
could be tested on a 1.3 with a FIB patch
1 port mode
AO[0] I0 I1 I2 I3 I4 I5 I6 I7 P7 P6 P5 P4 P3 P2 P1 P04 port mode
AO[0] I0 I4 P1 P0AO[1] I1 I5 P3 P2AO[2] I2 I6 P5 P4AO[3] I3 I7 P7 P6
I0 leading bit (always 0)I1 parity of PCN (even)I2 Active EDCI3 parity of reg. CompChThI4 parity of reg. CompMaskI5 parity of reg. TpSelectI6 SEU counter <1>I7 SEU counter <0>
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Parity bit - workaround (1)
schematic of parity-bit generation (part of MuxScheduler)
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Parity bit - workaround (2)
new schematic of parity-bit patch
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
Output device of ParityPCN generation - E_XNor2 (U1126)
Parity bit - workaround (3)
• Layout modification in FastControlof Beetle (could be done by a FIB)
TpSelectPar
ParityPCN
• 2 cuts• 2 connections
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
FIB patch (1)
• Polyimide partly removed with an UV laser
• 6 holes opened
• Signal lines still untouched
TPselectParParityPCN
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
FIB patch (2)
TPselectParParityPCN
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
FIB patch (3)
And another chip...
• Swap header bit I1 with I5• done with a FIB patch
(FEICO Munich)
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
FIB patch (4)
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EE-Gruppenmeeting 5. März 2007, Darmstadt
Sven LöchnerExperiment Elektronik, GSI Darmstadt
FIB patch (5)