Speaker: Bob Tsai
Advisor: Jie-Hong Roland Jiang
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Introduction
Flow
On Chip Variation (OCV)
Manual/automated netlist editing
Signal integrity and crosstalk
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PrimeTime VX, PrimeTime SI
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Sign-off
◦ A collective name to a series of verification steps
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Standard Parasitic Exchange Format
◦ Represent parasitic data of wires in a chip in ASCII
format
◦ Used for delay calculation and ensuring the signal
integrity
Setup Design
Check setup
Validate Prelayout
Constraints
Update
RTL
Create CHIP constraints
Update
SDC
CHIP level STA
Timing error?
Validate Constraints
Hand-off
fail
pass
Update
SDC
P&R
Validate Postlayout
Constraints
fail
Timing error?
pass
Tape-out
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Models the small difference in operating
parameters across the chip
Setup check: max delay for data path and min
delay for clock path
Hold check: min delay for data path and max
delay for clock path
Clock path 1 + data path max – clock path 2 + setup ≤ clock period
max = 3.04/3.8
D
0.48/0.6
CT3
0.64/0.8
CLK
CT1
0.52/0.65
Q
logic
D
Q
min = 1.6/2.0
setup = 0.2
CT2
Clock path 1 = 0.8+0.6 =1.4
Data path max = 3.8
Clock path 2 = 0.64+0.52=1.16
Setup = 0.2
=> The clock period must be at least 1.4+3.8-1.16+0.2=4.24
Clock path 1 + data path min – clock path 2 - hold ≥ 0
max = 3.04/3.8
D
0.48/0.6
CT3
0.64/0.8
CLK
CT1
0.52/0.65
Q
logic
D
Q
min = 1.6/2.0
hold = 0.1
CT2
Clock path 1 = 0.64+0.48 =1.12
Data path min = 1.6
Clock path 2 = 0.8+0.65=1.45
Hold = 0.1
=> No hold violation exists because 1.12+1.6-1.45-0.1=1.17 ≥ 0
Commands
Main functions
set_wire_load_model
(before P&R)
read_sdf
(after P&R)
read_parasitics
(after P&R)
check_timing
Checks for constraint problem such as
undefined clocking, input data arrival times,
and output data required times. (must-do)
report_design
Lists the attributes of the design, including
the chosen operating conditions, wire load
information, and design rules.
report_clock
Generates a report on the clocks defined for
the design, showing for each clock the name,
period, rise and fall times, and timing
characteristics such as latency and
uncertainty.
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size_cell
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insert_buffer | remove_buffer
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swap_cell
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Use write_change to output the changes
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The design should be fully placed and routed,
including clock trees, but without corefiller
fix_eco_timing –type {setup | hold}
fix_drc_timing –type {max_transition |
max_capacitance | max_fanout} –method
{size_cell | insert_buffer}
pt_shell> fix_drc_timing –type max_transition –method {size_cell} -verbose
pt_shell> fix_drc_timing –type max_transition –method {insert_buffer}
-buffer_list {BUFX1 BUFX2 BUFX3} -verbose
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Signal integrity
◦ The ability of an electrical signal to carry
information reliably and resist the effects of highfrequency electromagnetic interference from nearby
signals
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Crosstalk
◦ The undesirable electrical interaction between two
or more physically adjacent net due to capacitive
cross-coupling
Enable crosstalk analysis
∙ set si_enable_analysis TRUE
Read coupled parasitic data
∙ read_parasitics -format spef -keep_capacitive_coupling [spef_filename]
Do coupled delay analysis
∙ update_timing
Noise analysis
∙ update_noise
Generate noise report
∙ report_noise
D
logic
Q
D
CLK1
0
CLK3
0
CLK2
1
CLK4
1
Q
SEL
set_false_path
set_false_path –from
set_false_path –from
set_false_path –from
set_false_path –from
set_false_path –from
set_false_path –from
set_false_path –from
set_false_path –from
set_clock_group
CLK1
CLK2
CLK3
CLK4
CLK1
CLK4
CLK2
CLK3
–to
–to
–to
–to
–to
–to
–to
–to
CLK2
CLK1
CLK4
CLK3
CLK4
CLK1
CLK3
CLK2
set_clock_groups \
-logically_exclusive –name E1 \
-group {CLK1 CLK3}
-group {CLK2 CLK4}
set_active_clock [all_clocks]