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NAME

sxlib - a portable CMOS Standard Cell Library

sxlib library contains standard cells that have been developed at UPMC-ASIM/LIP6. This manual gives the list of available cells, with their behavior, width, maximum delay and input fan-in. This manual gives also few thumb rules to help the user to well use the cells. The given delay are the maximum (that means worst case for a generic .35 micron process). More precise delay can be found in ALLIANCE VHDL behavior files (.vbe file). Cell-name is built that way <behavior>_<output drive> (see explanations below).

Four files are attached to each cell:-
- ALLIANCE Layout ............... cell-name.ap
- ALLIANCE Transistor net-list .. cell-name.al
- ALLIANCE VHDL behavior ........ cell-name.vbe
- Compiled HILO behavior ........ 0000000xx.dat

And few files more:-
- CATAL ......................... ALLIANCE catalog file
- sxlib.cct ..................... Cell definition for HILO CAD tools
- CIRCUIT.idx ................... HILO catalog file
- sxlib.lib ..................... Cell definition for Synopsys CAD tools
- sxlib.db ...................... Compiled cell definition for Synopsys
- sxlib.sdb ..................... Icon definition for Synopys

PHYSICAL OUTLINE

sxlib uses the symbolic layout promoted by Alliance in order to provide process independence. All dimensions are in lambda units. The mapping to a specific process CIF or GDS2 layout must be performed by the s2r tool (symbolic to real), which uses a value for the lambda (e.g. 1 lambda=0.3um).

_________________
50 | VDD |
45 |_________________| x : place of virtual connector.
40 | x |
35 | x x | they are named : name_<y>
30 | x x |
25 | x x | for example : i0_20
20 | x | i0_25
15 | x | i0_30
10 |_________________|
5 | VSS |
0 |_________________|
0 5 10 15 20 25 30

All cells are 50 lambdas high and N times 5 lambdas wide, where N is the number of pitches. That is the only physical information given in the cell list below. Power supplies are in horizontal ALU1 and are 6 lambdas wide. Connectors are inside the cells, placed on a 5x5 grid. Half layout design rules are a warranty for any layer on any face, except for the power supply and NWELL. Cells can be abutted in all directions whenever the supply is well connected and connectors are always placed on the 5x5 grid.

DELAY MODEL

Cells have been extracted and simulated by using a generic 0.35um process in order to give realistic values for the delays and capacitances. We chose to give only the worst delay for each output signal, though it is not very realistic (since delay depends on each input, an input can be easily up to twice faster than another). However, we just wanted to give an idea of the relative delay.

Furthermore, we added 0.6ns to each output delay in order to take into account the delay due to the signal commutation. We have supposed the output drives the maximum capacitance. This capacitance have been computed as follow. We considered that a good slope signal for this process was 0.8ns. Then we searched for the capacitance required to obtain the same input and output slope (0.8ns) for the smaller inverter (inv_x1). That was 125fF. We simulated the same inverter without output capacitance. The delay difference was about 0.6ns. This result is not exactly the same for all cells, but 0.6ns is a good approximation.

The given delay is then a worst case (70degree, 2.7Volt, slow process, worst input), an idea of the typical delay can be obtain by dividing worst delay by 1.5, and best delay by dividing by 2. More detailed data can be found in GENERIC data included in the VHDL files (.vbe). Examples can be found at the end of this manual.

At last, to get a very better idea about the real delay without simulating the spice transistor netlist, it is required to use the TAS (1) tool, which is a timing static analyzer able to give the longer and the shorter path for a given process.

OUTPUT DRIVE

The output drive of a cell gives an information on the faculty for the cell to drive a big capacitance. This faculty depends on the rising and falling output resistance. The smaller the resistance, the bigger can be the capacitance. Minimum drive is x1. This corresponds to the smallest available inverter (inv_x1). x2 means the cell is equivalent (from the driving point of view) at two smaller inverters in parallel, and so on.

The maximum output drive is x8. It is limited because of the maximum output slope and the maximum authorized instantaneous current. If it was bigger the output slope could be very tight and the current too big.

With the 0.35um process, an x1 is able to drive about 125fF, x2 -> 250fF, x4 -> 500fF,x8 -> 1000fF. This is just an indication since if a cell is overloaded, the only consequence is to increase the propagation time. On the other hand, it is not very good to under-load a cell because this leads to a signal overshoot. Actually, for big gate, such as noa3ao322_x1, x1 means maximal driving strength reachable with a single logic layer, that can be much less than an inv_x1. That is why is the cell list below contains more precise drive strengh. As you can see noa3ao322_x1 as a output drive strengh of 0.6, that means 0.6 time an inverter, so say it can drive about 0.6*125fF=75fF.

With the 0.35um process, a 1 lambda interconnect wire is about 0.15fF, an average cell fan-in is 10fF. Then, if it needs about 50 lambdas to connect 2 cells, an x1 cell is able to drive about 7 cells (125/(10+50*.15)=7). With 100 lambdas, 5 cells, with 750 lambdas only 2 cells. Note that 50 lambdas means cells are very close one from each other, nearly abutted, 100 lambdas is an average value.

All this are indications. Only a timing analysis on the extracted transistor net-list from layout can tell if a cell is well used or not (see tas(1) for informations about static timing analysis).

BEHAVIOR

For most of cells, the user can deduce the cell behavior just by reading its name. That is very intuitive for inverter and more complex for and/or cells. For the last, the name gives the and/or tree structure. The input order for the VHDL interface component is always the alphabetic order.

inv : inversor buffer
buf : buffer
[n]ts : [not] tree-state
[n]xr : [not] xor inputs
[n]mx : [not] multiplexor inputs with coded command
[n][sd]ff : [not] [static|dynamic] flip-flop inputs
[n]oa... : [not] and/or function (see below)

and_or cell (YACC (1) grammar):-

NAME : n OA_CELL -> not OA_CELL
| OA_CELL -> OA_CELL

OA_CELL : OPERATOR INPUTS -> function with INPUTS inputs
| OPERATOR OA_CELLS INPUTS -> function with INPUTS inputs
where some inputs are OA_CELL

OPERATOR : a -> and
| o -> or
| n -> not

OA_CELLS : OA_CELLS OA_CELL -> list of OA_CELL
| OA_CELL -> last OA_CELL of the list

INPUTS : integer -> number of inputs

The input names are implicit and formed that way i<number>.
They are attributed in order beginning by i0.

nx where x is a number means there are x inverters in parallel. For
example an23 is an and with 3 inputs of which two are inverted, that
is and( not(i0), not(i1), i2).

Examples:- (some are not in sxlib)

na2 : not( and(i0,i1))
on12 : or( not(i0), i1)
noa2a22 : not( or( and(i0,i1), and(i2,i3)))
noa23 : not( or( and(i0,i1), i3))
noao22a34 : not( or( and( or(i0,i1), i2), and(i3,i4,i5), i6, i7))

Note that xr2 could not be expressed with an and/or formulea even if
xr2 = or( and( not(i0), i1), and( not(i1), i0)) = oan12an122
but the input names are not well distributed.

CELL LIST

All available cells are listed below. The first column is the pitch width. The pitch value is 5 lambdas. The height is 50. Area is then <number>*5*50.

The second column is the output drive strenght compared with the inv_x1 output drive strenght (see explanation above in section OUTPUT DRIVE).

The following column is the delay in nano-seconds. Remember this delay corresponds to the slower input+0.6ns (see explanation above in section DELAY MODEL).

The last column gives the function behavior with input capacitance. / means not, + means or, . means and, ^ means xor. Each input is followed by fan-in capacitance in fF, (e.g. i0<11> means i0 pin capacitance is 11fF).

For some cells, such as fulladder, it was not possible to internally connect all inputs. That means there are several inputs that must be externally connected. In the following list, these inputs are followed by a star (*) character in the equation.

For example, fulladder equation is sout <= (a* . b* . cin*). a* replaces a0, a1, a2, a3 that must be explicitly connected by the user. Note also few cells have more than one output. In that case there are several lines in the list, one by output.
=================================================================
WIDTH NAME DRIVE DELAY BEHAVIOR with cin
-------------------------------------------------------- INVERSOR
3 inv_x1 1.0 0.7 nq <= /i<8>
3 inv_x2 1.6 0.7 nq <= /i<12>
4 inv_x4 3.6 0.7 nq <= /i<26>
7 inv_x8 8.4 0.7 nq <= /i<54>
---------------------------------------------------------- BUFFER
4 buf_x2 2.1 1.0 q <= i<6>
5 buf_x4 4.3 1.0 q <= i<9>
8 buf_x8 8.4 1.0 q <= i<15>
------------------------------------------------------ THREE STATE
6 nts_x1 1.2 0.8 IF (cmd<14>) nq <= /i<14>
8 nts_x2 2.4 0.9 IF (cmd<18>) nq <= /i<28>
10 ts_x4 4.3 1.1 IF (cmd<19>) q <= i<8>
13 ts_x8 8.4 1.2 IF (cmd<19>) q <= i<8>
-------------------------------------------------------------- AND
4 na2_x1 1.0 0.9 nq <= /(i0<11>.i1<11>)
7 na2_x4 4.3 1.2 nq <= /(i0<10>.i1<10>)
5 na3_x1 0.9 1.0 nq <= /(i0<11>.i1<11>.i2<11>)
8 na3_x4 4.3 1.3 nq <= /(i0<10>.i1<10>.i2<10>)
6 na4_x1 0.7 1.0 nq <= /(i0<10>.i1<11>.i2<11>.i3<11>)
10 na4_x4 4.3 1.4 nq <= /(i0<10>.i1<11>.i2<11>.i3<11>)
5 a2_x2 2.1 1.0 q <= (i0<9>.i1<11>)
6 a2_x4 4.3 1.1 q <= (i0<9>.i1<11>)
6 a3_x2 2.1 1.1 q <= (i0<10>.i1<10>.i2<10>)
7 a3_x4 4.3 1.2 q <= (i0<10>.i1<10>.i2<10>)
7 a4_x2 2.1 1.2 q <= (i0<10>.i1<10>.i2<10>.i3<10>)
8 a4_x4 4.3 1.3 q <= (i0<10>.i1<10>.i2<10>.i3<10>)
5 an12_x1 1.0 1.0 q <= (/i0<12>).i1<9>
8 an12_x4 4.3 1.1 q <= (/i0<9>).i1<11>
--------------------------------------------------------------- OR
4 no2_x1 1.0 0.9 nq <= /(i0<12>+i1<12>)
8 no2_x4 4.3 1.2 nq <= /(i0<12>+i1<11>)
5 no3_x1 0.8 1.0 nq <= /(i0<12>+i1<12>+i2<12>)
8 no3_x4 4.3 1.3 nq <= /(i0<12>+i1<12>+i2<11>)
6 no4_x1 0.6 1.1 nq <= /(i0<12>+i1<12>+i2<12>+i3<12>)
10 no4_x4 4.3 1.4 nq <= /(i0<12>+i1<12>+i2<12>+i3<12>)
5 o2_x2 2.1 1.0 q <= (i0<10>+i1<10>)
6 o2_x4 4.3 1.1 q <= (i0<10>+i1<10>)
6 o3_x2 2.1 1.1 q <= (i0<10>+i1<10>+i2<9>)
10 o3_x4 4.3 1.2 q <= (i0<10>+i1<10>+i2<9>)
7 o4_x2 2.1 1.2 q <= (i0<10>+i1<10>+i2<10>+i3<9>)
8 o4_x4 4.3 1.3 q <= (i0<12>+i1<12>+i2<12>+i3<12>)
5 on12_x1 1.0 0.9 q <= (/i0<11>)+i1<9>
8 on12_x4 4.3 1.1 q <= (/i0<9>)+i1<10>
--------------------------------------------------------- AND/OR 3
6 nao22_x1 1.2 0.9 nq <= /((i0<14>+i1<14>).i2<14>)
10 nao22_x4 4.3 1.3 nq <= /((i0<8> +i1<8>) .i2<9>)
6 noa22_x1 1.2 0.9 nq <= /((i0<14>.i1<14>)+i2<14>)
10 noa22_x4 4.3 1.3 nq <= /((i0<8> .i1<8>) +i2<9>)
6 ao22_x2 2.1 1.2 q <= ((i0<8>+i1<8>).i2<9>)
8 ao22_x4 4.3 1.3 q <= ((i0<8>+i1<8>).i2<9>)
6 oa22_x2 2.1 1.2 q <= ((i0<8>.i1<8>)+i2<9>)
8 oa22_x4 4.3 1.3 q <= ((i0<8>.i1<8>)+i2<9>)
--------------------------------------------------------- AND/OR 4
7 nao2o22_x1 1.2 1.0 nq <= /((i0<14>+i1<14>).(i2<14>+i3<14>))
11 nao2o22_x4 4.3 1.4 nq <= /((i0<8> +i1<8>) .(i2<8> +i3<8>))
7 noa2a22_x1 1.2 1.0 nq <= /((i0<14>.i1<14>)+(i2<14>.i3<14>))
11 noa2a22_x4 4.3 1.4 nq <= /((i0<8> .i1<8>) +(i2<8> .i3<8>))
9 ao2o22_x2 2.1 1.2 q <= ((i0<8>+i1<8>).(i2<8>+i3<8>))
10 ao2o22_x4 4.3 1.3 q <= ((i0<8>+i1<8>).(i2<8>+i3<8>))
9 oa2a22_x2 2.1 1.2 q <= ((i0<8>.i1<8>)+(i2<8>.i3<8>))
10 oa2a22_x4 4.3 1.4 q <= ((i0<8>.i1<8>)+(i2<8>.i3<8>))
--------------------------------------------------------- AND/OR 5
7 noa2ao222_x1 0.7 1.1 nq <= /((i0<11>.i1<11>)+((i2<13>+i3<13>).i4<13>))
11 noa2ao222_x4 4.3 1.4 nq <= /((i0<11>.i1<11>)+((i2<11>+i3<11>).i4<11>))
10 oa2ao222_x2 2.1 1.2 q <= ((i0<8> .i1<8>) +((i2<8> +i3<8>) .i4<8>))
11 oa2ao222_x4 4.3 1.3 q <= ((i0<8> .i1<8>) +((i2<8> +i3<8>) .i4<8>))
--------------------------------------------------------- AND/OR 6
10 noa2a2a23_x1 0.8 1.2 nq <= /((i0<13>.i1<14>) +(i2<14>.i3<14>)
+(i4<14>.i5<14>))
13 noa2a2a23_x4 4.3 1.3 nq <= /((i0<13>.i1<14>) +(i2<14>.i3<14>)
+(i4<14>.i5<14>))
12 oa2a2a23_x2 2.1 1.4 q <= ((i0<13>.i1<14>) +(i2<14>.i3<14>)
+(i4<14>.i5<14>))
13 oa2a2a23_x4 4.3 1.4 q <= ((i0<13>.i1<14>) +(i2<14>.i3<14>)
+(i4<14>.i5<14>))
--------------------------------------------------------- AND/OR 7
9 noa3ao322_x1 0.6 1.2 nq <= /((i0<13>.i1<13>.i2<12>)
+((i3<13>+i4<13>+i5<13>).i6<13>))
11 noa3ao322_x4 4.3 1.4 nq <= /((i0<10>.i1<9>.i2<9>)
+((i3<9>+i4<9>+i5<9>).i6<9>))
10 oa3ao322_x2 2.1 1.2 q <= /((i0<10>.i1<9>.i2<9>)
+((i3<9>+i4<9>+i5<9>).i6<9>))
11 oa3ao322_x4 4.3 1.3 q <= /((i0<10>.i1<9>.i2<9>)
+((i3<9>+i4<9>+i5<9>).i6<9>))
--------------------------------------------------------- AND/OR 8
14 noa2a2a2a24_x1 0.6 1.4 nq <= /((i0<14>.i1<14>)+(i2<13>.i3<13>)
+(i4<13>.i5<13>)+(i6<14>.i7<14>))
17 noa2a2a2a24_x4 4.3 1.7 nq <= /((i0<14>.i1<14>)+(i2<14>.i3<13>)
+(i4<13>.i5<13>)+(i6<14>.i7<14>))
15 oa2a2a2a24_x2 2.1 1.5 q <= ((i0<14>.i1<14>)+(i2<14>.i3<13>)
+(i4<13>.i5<13>)+(i6<14>.i7<14>))
16 oa2a2a2a24_x4 4.3 1.6 q <= ((i0<14>.i1<14>)+(i2<14>.i3<13>)
+(i4<13>.i5<13>)+(i6<14>.i7<14>))
------------------------------------------------------ MULTIPLEXER
7 nmx2_x1 1.2 1.0 nq <= /((i0<14>./cmd<21>)+(i1<14>.cmd))
12 nmx2_x4 4.3 1.3 nq <= /((i0<8>./cmd<14>)+(i1<9>.cmd))
9 mx2_x2 2.1 1.1 q <= (i0<8>./cmd<17>)+(i1<9>.cmd)
10 mx2_x4 4.3 1.3 q <= (i0<8>./cmd<17>)+(i1<9>.cmd)
12 nmx3_x1 0.4 1.2 nq <= /((i0<9>./cmd0<15>)
+(((i1<8>.cmd1<15>)+(i2<8>./cmd1)).cmd0))
15 nmx3_x4 4.3 1.7 nq <= /((i0<9>./cmd0<15>)
+(((i1<8>.cmd1<15>)+(i2<8>./cmd1)).cmd0))
13 mx3_x2 2.1 1.4 q <= ((i0<9>./cmd0<15>)
+(((i1<8>.cmd1<15>)+(i2<8>./cmd1)).cmd0))
14 mx3_x4 4.3 1.6 q <= ((i0<9>./cmd0<15>)
+(((i1<8>.cmd1<15>)+(i2<8>./cmd1)).cmd0))
-------------------------------------------------------------- XOR
9 nxr2_x1 1.2 1.1 nq <= /(i0<21>^i1<22>)
11 nxr2_x4 4.3 1.2 nq <= /(i0<20>^i1<21>)
9 xr2_x1 1.2 1.0 q <= (i0<21>^i1<22>)
12 xr2_x4 4.3 1.2 q <= (i0<20>^i1<21>)
-------------------------------------------------------- FLIP-FLOP
nq <=/((i0<11>./cmd<13>)+(i1<7>.cmd))
18 sff1_x4 4.3 1.7 IF RISE(ck<8>)
q <= i<8>
24 sff2_x4 4.3 1.9 IF RISE(ck<8>)
q <= ((i0<8>./cmd<16>)+(i1<7>.cmd))
28 sff3_x4 4.3 2.4 IF RISE(ck<8>)
q <= (i0<9>./cmd0<15>)
+(((i1<8>.cmd1<15>)+(i2<8>./cmd1)).cmd0)
------------------------------------------------------------ ADDER
16 halfadder_x2 2.1 1.2 sout <= (a<27>^b<22>)
2.1 1.0 cout <= (a.b)
18 halfadder_x4 4.3 1.3 sout <= (a<27>^b<22>)
4.3 1.1 cout <= (a.b)
20 fulladder_x2 2.1 1.8 sout <= (a*<28>^b*<28>^cin*<19>)
2.1 1.4 cout <= (a*.b*+a*.cin*+b*.cin*)
21 fulladder_x4 4.3 2.2 sout <= (a*<28>^b*<28>^cin*<19>)
4.3 1.5 cout <= (a*.b*+a*.cin*+b*.cin*)
---------------------------------------------------------- SPECIAL
3 zero_x0 0 0 nq <= ’0’
3 one_x0 0 0 q <= ’1’
2 tie_x0 0 0 Body tie cell
1 rowend_x0 0 0 Empty cell
==================================================================

NEW CELLS

It is possible to add new cells in the library just by providing the 3 files .ap, .al and .vbe in the standard cell directory. The layout view can be created with the symbolic editor graal. The physical outline is given above. The net-list view can be automatically generated with the lynx extractor. The behavioral view must be written by the designer and checked with the yagle functional abstractor. The file must contain the generic fields in order to be used by the logic synthesis tools and the I/Os terminals must be in the same order (alphabetic) in the .vbe and .al files.

If you develop new cells, please send the corresponding files to alliance−users [AT] asim.fr

VHDL FILES

You can find below the commented VHDL GENERIC for the na2_x4 cell.
ENTITY na2_x4 IS
GENERIC (
CONSTANT area : NATURAL := 1750; -- lamba * lambda
CONSTANT transistors : NATURAL := 10; -- number of
CONSTANT cin_i0 : NATURAL := 10; -- femto Farad for i0
CONSTANT cin_i1 : NATURAL := 10; -- femto Farad for i1
CONSTANT tplh_i1_nq : NATURAL := 606; -- propag. time in pico-sec
-- from i1 falling
-- to nq rizing
CONSTANT rup_i1_nq : NATURAL := 890; -- resitance in Ohms when nq
-- rizing due to i1 change
CONSTANT tphl_i1_nq : NATURAL := 349; -- propag time when nq falls
CONSTANT rdown_i1_nq : NATURAL := 800; -- resist when nq falls
CONSTANT tplh_i0_nq : NATURAL := 557; -- idem for i0
CONSTANT rup_i0_nq : NATURAL := 890;
CONSTANT tphl_i0_nq : NATURAL := 408;
CONSTANT rdown_i0_nq : NATURAL := 800
);
PORT (
i0 : in BIT;
i1 : in BIT;
nq : out BIT;
vdd : in BIT;
vss : in BIT
);

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