7D15 - Tektronix 7000 Series Manual

can be obtained visually from the ana-
log
d
is play. The 100Χ measurement
averagi ng im proves the accuracy and
resolution of the measurement. Th e ac-
curacy in th is case is wit h in 4 ns
(.00036%) .
time between two voltage
levels
R
isetime, th e time between the 10%
and 90%
p
ulse levels, or the time re-
quire d for α tran sducer to rise from one
level to anot h er, can easily
b
e acq u ired
from the 7D15's TIME Α-Β M ode.
Th e 7D15 offers digital rea d o ut, accu-
racy an d convenience in ma king t h ese
measureme n ts . For exam p le, if you are
ma ki ng α series of risetime measure-
ments where the 10% an d 90% levels
are
n
ot c h anging, eac h risetime is
d
igi-
tally read out on th e crt ; this eliminates
t
h e nee
d
to carefully
p
osition t h e wave-
form, and, then count
d
ivisions on t h e
crt.
Cloc k
7603
0
Delaye d
Swee p
Gate
C)"+
M ainf r a m e
V
ertical M o d e . . . . . . . . . . . . . . . . . . . . Alte rnate
He r ί z οπ t α t
M
o d e . . . . . . . . . . . . . . . . . . . . . . . . Α
713115
Α Trigge r So ur ce . . . . . . . . . . . . . . L
eft
V
e r tical
M o d e . . . . . . . . . . . . . . . . . . . . . . . . . . Tim Α- ι Β
Ti m e
B
ase
Averg . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Χ1000
Main
Time/Div . . . . . . . . . . . . . . . . . . . . . . . . .
Cloc k . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
n
s
Tr igge r i ng
,
. .
Gate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
N
o r m
Β Delaye d M o de 1n de p en dent . . . . . . . . . . . . . .
Displaye d W aveform . . . . . . . . . Pse ud o Gate
Tr igger
L
evel . . . . . . . . . . . . . . . . Α .6 V, Β 5.4 V V
ertical Am plif ie r
Slo pe Α & Β . . . . . . . . . . . . . . . . . . . . . . . . . . . + Disp lay
M
ode . . . . . . . . . . . . . . . . . . . . . . . . Ch 1
Co up le Α & Β . . . . . . . . . . . . . . . . . . . . . . . . . DC Trigger Sou rce . . . . . . . . . . . . . . . . . . . . . . C h 1
Source . . . . . . . . . . . . . . . . . . . . . . . . . . . Ιπρυt Α
V
olts/Div . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Wh en ma king a
d
j ustments to yo ur cir-
F
ig . 10 .
E
q
ui p ment setu p for risetime measurement.
c
u itry, you can resolve small changes
in risetime with outstandi n g ease and
than 125 ns . T he trigger arming gate sign al from t h e c h annel Α in p ut (in the
resolution . However, t h e 7D15 is not
(t he
d
elayed swee p gate) must be con-
TIM Α-Β mo de) . Wh en in, each trigger
recommended for measuring risetimes
nected to both
t
he Α A RM an d
t
h e Β circuit receives its trigger 1
faster than 125 n s.
gger signal from
ARM connectors . Set the Α trigger level
its respective in put connector.
Th e two separate trigger circuits of th e
co ntrol to trigger at the 10%
p
oint an d
7D15 and
t
h e ability to set exact trigger
t h e Β trigger level co ntrol for th e 90%
Trigger armi n g is required for th is
levels throug h
t h e two TR IG LEVEL p
oint . Now α ty pical time interval mea-
measurement, because chann el Β must
j
ac k allows you to ma k e very accurate
surement (TIM Α-Β) can
b
e
d
one by
know whic h
p u lse to trigger on with re-
-isetime measurements with
t
h e 7D15 .
moving the intensifie d zone from one
seect to the un delayed p ulse . Con nect
Again, trigger arming can
b
e used to
risetime to anot her . This allows you to
the
d elayed swee p gate to both trigger
select α
p
articular
p
ulse i n non-re peti-
accurately
p
erform selective risetime
arming in put j ac ks.
tive
p
ulse trains .
measurements with greater resol u tion
Wit h the oscillosco pe vertical mo de set
Fig . 10 s hows the eq ui pment set up for
t han wit h α conventional oscillosco pe.
for alternate trace sweeps, trigger the
measuring t h e risetime of α cloc k
p
ulse
scope on the un delayed pulse (c h ann el
as it is in put into α flip-flo p . This is α
p
ro
p
agation delay
1) .
Now adjust the intensifie d zone so
fΙίρ-flo p whic h regυί res α cloc k
p
ulse
that it begi ns before the rise of the υη -
,
risetime of 150 ns from the 0.6 V to th e
d
elayed pulse, an d en ds before th e rise
5.4 V level.
The two signal inputs to the 7D15 trig- of th e
d
elayed p u lse. The
p
ro pagation
ger circuits allow you to ma k e p
ro paga- d elay is then read out on th e C R T. The
The TRIGG ER SLOPE controls i n
t
his
tion
d
elay measurements
q
uickly an d
meas urement in this case is 76 .60 ns .
measurement are both set to + . To set
easily. Fig . 11 shows the equi p ment set-
t he T RIGG ER LEVEL controls, connect
up re quire d to measure the
p
ro paga-
F
oGER
r
LEVEL
accu racy,
b
ot h
t
he et for
α DVM to one TRIG LEVEL jac k at α
tion
d
elay ex perienced by α cloc k sig-
the LEVEL controls should be s
time, and set the Α trigger level for 0.6
ηαΙ as it
p
asses throug h seve n TTL
same voltage level . ri n g can be ob-
V an d Β trigger level for 5.4
V . W
it h
t
h e
gates.
tained either by measuring the voltage
TIM Α~Β M OD E p us hbutton
p
ressed ,
levels throug h
t h e TR IG LEVEL jac ks
t he rί et ίme is read directly on the C RT.
In th is setup, the un delayed pulse is
with α DVM, or by app lying the
d
esired
1η
t
his case the αί diec measurement
con n ected to bot h channel 1 of the ver-
voltage level to each j ac k (see the
d is-
is 155.60 ns . The accuracy is within 2
n
s
tical am p lifier a nd chann el Α of the
cussion of trigger level in t he introduc-
or 1 .3% .
7D15 ; the
d
elayed p ulse is connecte d
tion sectio n ).
to chann el 2 of the vertical am p lifier
1 0
T h is method can be easily used for
an d
c hannel Β of th e 7D15 . The 7D15's
measuri n g rise an d fall times slower
SO UR CE
I
NPUT Β pus h button d eter-
mines the so u rce of the trigger signal
10
for c h annel Β. Wh en out, it receives its