Some thoughts on “ART2GBT”
ASIC
Sorin Martoiu, IFIN-HH
De-serialize
Hit
Selection
Data
formatting
De-serialize
Hit Sel
Data
formatting
De-serialize
Hit
Sel
Data
formatting
How fast the hit selection can be?
1. (Asynchronous) Smart Token:
FLAG_IN
FLAG_IN
FLAG_IN
FLAG_IN
2. Cascaded Priority Encoders:
FLAGS_IN
Token stops when
SUM = MAX_HIT_LIST
How fast the hit selection can be?
(Asynchronous) Smart Token
Cascaded Priority Encoders
ARTIX7
SPARTAN6
ASIC*
(ns)*
(ns)*
(ns)*
synth
6.5
9.876
P&R
11.04
12.2
Synth
3.18
4.506
P&R
5.25
5.045
* MAX_HITS = 8
** Very preliminary. 0.18 um tech MOSIS
SCMOS (tsmc) (not IBM 0.13) / OSU FreePDK
6.5
How big the ASIC can be?
• Full layout (fast attempt, not fully
tested, …)
• De-serializers
• Hit selection
• Data formatting (simple
mux with pass- transistors)
• (very) crude estimation:
• 700 x 700 um2
• No triplication (x4)
• 0.18 -> 0.13 (x 0.7)
• tech, std. cells, pads…
How big the ASIC can be?
Number of I/O pads:
• Inputs:
32 x 2
• Outputs:
40 x 2
• Total:
144 + pwr, clk, …
Options:
• Reduce GBT i/f
• 10 elinks@320MHz
• Staggered pads
• C4 ball bonds
5-bit Chip ID:
max hits = 7 (80 bits = 7x11 + 3 spare)
DOUT[39:0]
A2 – 5+6 bits
A5 – 5+6 bits
A12 – 5+6 bits
BCID/ART
DOUT[79:40]
A16 – 5+6 bits
empty
empty
BCID/ART
“000....00000”
“000....00000”
VMM 0, STRIP 0
ambiguity
32-bit Hit List:
max hits = 8 (80 = 8x6 + 32)
32-bit hit list
2
12
5
16
BCID/ART
DOUT[39:0]
DOUT[79:40]
..CID/ART
ART-6bits
ART-6bits
ART-6bits
ART-6bits
B..
empty
Preliminary Conclusions
• Hit selection can be done in 0.5 BC, possibly even
less (FPGA and ASIC)
• Design fits well in low-range FPGAs (SPARTAN6 or
ARTIX7 – probably valid for Altera devices too)
• ASIC implementation looks feasible in <0.18um
tech
• Final chip area is governed by the number of
pads/packaging solution
• Power?
Spare Slides
BCID transmission
Cavern
USA15
Fixed Latency
ART2GBT/
VMM
3 2 1
GBT
(TX)
GBT
(RX)
3 2 1
BCID
counter
BCID
counter
TTC SYSTEM
TRIGGER
PROC
8 hits
8 hits
4+4 hits
4+4 hits
2 of 4 traces partially lost
1 of 4 trace lost
2 of 8 trace lost
Drift gap timing variation turned off…