dff_2x.d.clk.q.h_2.sp #1

*	$Id$

*	DO NOT EDIT.  This file generated automagically.
*	Created: Wed Jul 28  7:48:22 1999
*	User: ryu

*	Char:	D-Flop Hold Time Characterization
*	Data:	"d"
*	Clock:	"clk"
*	Q:	"q"
*	C:	"mout"
*	Trans:	"lh"

*--- SETUP ---------------------------------------------------
.include '/home/ryu/src/autochar/autochar-1.5.3/tech/tsmc35/include/ttlh.sp'
.include 'dff_2x.sp'
.include /home/ryu/src/autochar/autochar-1.5.3/tech/tsmc35/lib/autochar.sp
.options
+	prpts
+	rawpts
+	format
.param ihold = 0
.param setup_hold_scale = '1e-12'
.param hold = 'ihold*setup_hold_scale'
.param slewrate = '4.00002e-11'
.param slew_start = '0.1'
.param slew_end = '0.9'

*--- INPUTS --------------------------------------------------
vclk vclk 0 pulse (
+	'0'
+	'vhigh'
+	'1ns+trise/2'
+	'0'
+	'0'
+	'pwidth+trise/2+tfall/2'
+	'period')
vd vd 0 pulse (
+	'0'
+	'vhigh'
+	'1ns+trise+pwidth'
+	'trise'
+	'tfall'
+	'pwidth+hold'
+	'4*period')

*--- TEST CIRCUIT --------------------------------------------
xdbuf vd d ebuffer
xclkbuf vclk clk slewbuffer
xflop
+	q	$ q:o
+	d	$ d:i
+	clk	$ clk:i
+	diff_1	$ clk_n:i
+	dff_2x
e1 diff_1 0 clk vdd -1

*--- LOADS ---------------------------------------------------
c0 q 0 100ff

*--- MEASURE -------------------------------------------------
.option autostop
.measure tran ihold param='ihold'
.measure tran hold param='hold'
* Measure hold time:
.measure tran hold_lh delay v(clk) val='vhigh/2' rise=2
+	targ=v(d) val='vhigh/2' cross=2
* Measure clock slew rate:
.measure tran clkslew delay v(clk) val='0+0.1*vhigh' rise=2
+	targ=v(clk) val='0+0.9*vhigh' rise=2

* Measure internal criterion node:
.measure tran vcrit find v(xflop.mout)
+	when v(clk)='0.8*vhigh' rise=2
.measure tran optpass param='(vhigh-vcrit)/vhigh'

*--- TRANSIENT -----------------------------------------------
* Measure final clock->q time:
.measure tran clk_q delay v(clk) val='vhigh/2' rise=2
+	targ=v(q) val='vhigh/2' rise=1
.trans 5ps '2*period'

*--- CONTROL -------------------------------------------------
.control
# find fail
modif loop=20 stop optpass le 0.8 ihold -= (0)600 prtbl
set fail = $ihold
# find pass
modif loop=20 stop 0.8 le optpass ihold += (0)600 prtbl
set pass = $ihold

set i = 0
set window = `expr $pass - $fail`

# Save measurements
set save_hold = $hold_lh
set save_clkslew = $clkslew
set save_clk_q = $clk_q
set save_vcrit = $vcrit
set save_optpass = $optpass

echo Iteration $i: Pass = $pass, Fail = $fail, Window = $window, hold = $save_hold

# Binary search
while ($window > 5) 
    set i = `expr $i + 1`
    set sum = `expr $pass + $fail`
    set midpoint = `expr $sum / 2`

    modif loop=1 ihold = $midpoint prtbl

    if ($optpass > 0.8 or $optpass eq 0.8)
	set pass = $midpoint

	# Save measurements
	set save_hold = $hold_lh
	set save_clkslew = $clkslew
	set save_clk_q = $clk_q
	set save_vcrit = $vcrit
	set save_optpass = $optpass

    else
	set fail = $midpoint
    end
    set window = `expr $pass - $fail`

    echo Iteration $i: Pass = $pass, Fail = $fail, Window = $window, hold = $save_hold
end

echo Final hold_lh = $save_hold
echo Final clkslew = $clkslew
echo Final clk_q = $clk_q
echo Final vcrit = $vcrit
echo Final optpass = $optpass

.endc

* Alter slewrate:
.alter
.param slewrate = '7.99998e-11'
.alter
.param slewrate = '1.2e-10'
.alter
.param slewrate = '1.600002e-10'
.alter
.param slewrate = '3.19998e-10'
.end