well. At this point, boundary and internal scan can be
added and ATPG vectors generated. A Preliminary
Design Review i s then held with the customer to review
and to appro ve t he r esul ts of the design conver sio n.
Preli minar y Design R eview (PDR)
The follow ing it ems are review ed at the PD R:
•Confirm Netlist Checke r (v3) and Test Vector Checker
(tvc) files corr ect
•I /O buffer li sti ng and bonding diagram
•Pr eli minary t estabili ty compiler report
•R out e cl ock t ree and analysi s of w or st case and best
case dela y
•Ver il og simulat ion at-speed
-nominal, w or st case, best case (w ith no t iming
violations)
•Review critical path information (tSU, tHOLD, tPD)
-Veri log or Veritime estimates
•I/O electrical specification s
•E lectro migration calcu lation
Fina l Desi gn Revi ew (FDR )
Beyond this point, the design process follows that of a
tradit i onally desi gned gate arra y. The cells are placed and
routed, a post - route sim ulation is per f ormed, and checks
are performed to verify conformance with electrical and
design r ules, and t o confirm t he Logi c Versu s Schemat ic
(LVS) is correct. An FDR is held with the customer to
review and appr ove t he post r oute data, and t o author ize
mask m aking and prototype fabric ation.
The FDR is the last joint review between Atmel and the
customer before committing to prototypes. Prior to this
meetin g, both A tmel and the customer will have r evie wed
the post-route Verilog-XL simulation incorporating the
back annotation data. The customer may receive back
annotation data for complete post-route simulation on
their CAE systems. Atmel guarant ees si li con perfor mance
equal to or better than that predicted by the post-route
Verilog-XL simulations. T he it ems to be reviewed at FDR
ar e as follows:
•Updates of cell m apping and timing (if any)
•P ost-route netlist check (v 3)
-post-route netlist changes
•Post -route t iming simulation to specificat ion
-review clock timing
-at speed
-clock skew (if req uired)
-listing of timing war nings with explanation
•S tatic path anal ysis (as speci fi ed)
•E lectro migration calcu lation
•Bo nding diagrams and pi n list
-bond pad plot
•LVS/DRC/ERC
P r oto type Delivery
Atmel will deliver 10 prototypes in ceramic or TQFP
packages to the customer. The units are to verify the
functional ity and el ectrical perf ormance of the gat e ar ra y.
S ynt hesis f r om a Hardw ar e Descr iptio n
L a nguage ( HDL)
T here has been an incr ease in the use of HDLs to desi gn
FPGA s and P LDs as more of the de sign platforms offer
this capability. Two of the most popular languages are
VHDL and Verilog-HDL. Using a logic synthesis
technique, the behavioral l evel description of an FP GA or
PLD can be mapped into a functionally equivalent gate
array netlist. Both hardware description languages are
supported by the Synopsys Design Compiler. This
FPGA/PLD to gate array conversion methodology
requi res the least amount of data conversion and allows
the flexibility to incorporate such features as memory,
testability, or higher order logic functions into the gate
array. This technique is also effective when the need to
co nsolidate several FPGA or PLD designs into one gate
array exists. Synthesis from an HDL offers the most
efficient utilization of the gate array, at the expense of
timing matching. Should the user require them, VHDL
descriptions of the convert ed FPG As or PLD s, as well as
the gate array implementation, can be provided by
exporting the net li sts thr ough Synopsys.
Testabili ty Improvement and Auto matic Test
P atter n Generation
The incorpor ation of te stability impr oveme nt circuitry in to an
ASI C design becomes more impor tant as the density of the
des ig n i ncr eases . The sa me can be said for conve rs i on and
consolidation of large numbers of dense FPGAs or PLDs
into a gate array. The insert i on of scan path s w i t hin an AS I C
and testing via ATPG can provide an easy means of
scr eening m anufact ur i ng-r el ated def ects duri ng te st i ng, w it h
a rela tively small silic o n usage penalty. Using ATPG is only
a supplem ent t o f unc t i onal t es t v ect or s, not a replacement .
The process consists of replacing existing flip-flops with
scan flip-flops and connecting them up to form scan
chains. An in put pin and output pi n m ust be i dent if ied for
each scan chain. In general, scan chains should not
e x ceed 64 flip- flops in length. T hus, for a design with 600
flip-flops, 10 input pins and their corresponding output
p ins must be ident ified. E xist ing p ins may be m ultiplexed
for thi s use if the design i s pin li m it ed. Additional pins are
required for the Test Enable (TE) signal and a Test M ode
(TM) signal. The TE pin is used to control the flip-flops,
placi ng them in eit her normal mode or scan mode.
CMOS ASIC
9-105