Delay Time - Tektronix R Instruction Manual

of the pulse generator (point A to ground) is
maintained at 50 ohms. The actual output
waveform of the pulse generator is shown
in Fig. 2-2.
}-—— 8 MSEC. ——
l u U
| + APPROX. 700 ;SEC oa
Fig. 2-2. Typical output waveform from the pulse generator with
COLLECTOR SOURCE VOLTS switch in P-N-P (-) position, Pulse
repetition rate is 120 per second.
The SERIES RESISTOR permits you to drive
the transistor under test from an impedance
approximating that which you will actually use
in your circuit.
The value of the COLLECTOR LOAD
RESISTOR is adjustable, both internally and
externally, so that you can choose a value
which most nearly meets your requirements.
Connecting the load resistor externally min-
imizes stray capacitance, which decreases the
response time of the transistor. The voltage
change across the internal current-measuring
resistance is fed into the vertical amplifier
of the oscilloscope.
The four "transistor-plus-circuit'" charac-
teristics to be discussed and measured are
+ INPUT
VOLTAGE
WAVEFORM
COLLECTOR
CTURN-ON TIME} VOLTAGE (TURN-OFF TIME}
| WAVEFORM a
|
+ |
t
on -- tf TRANSISTOR _
CUTOFF
DELAY TIME \ FALL TIME
RISETIME
STORAGE TIME
042
Fig. 2-3. Drawing illustrating the pulse-response characteristics
of a p-n-p transistor in the grounded-emitter configuration.
delay time, risetime, storage time and falltime.
All are shown with their relationship to the
input pulse in Fig. 2-3.
The display presented by means of the Type
R Plug-In Unit contains the same information
shown in Fig. 2-3, but is presented somewhat
differently in order to permit you to derive
a maximum of pulse-response information from
a single setting of the controls. A typical
display on a Tektronix oscilloscope incorporat-
ing a delay line is shown in Fig. 2-4.
STORAGE TIME
FALL TIME
(Tun oFF TIME)
tb Petpet tt ttt ttt tt +H
: =n RISETIME
(TURN-ON TIME)
ZERO TIME DELAY TIME
REFERENCE Daa
Fig. 2-4. Double-triggered display of the switching characteristics
of a p-n-p transistor.
Definitions of pulse-response terms as used
in this manual are as follows:
DELAY TIME (propagation time): The time
between the application of an input pulse and
the time when the output pulse attains 10 per
cent of its maximum amplitude in the direction
of increasing collector current.
RISETIME: The time interval during which
the amplitude of the output voltage changes
from 10 per cent to 90 per cent of its maximum
value in the direction of increasing collector
current,
TURN-ON TIME: The time between the applica-
tion of an input pulse and the time when the
output pulse attains 90 per cent of its maximum
amplitude. This term is the sum of the delay
time and risetime.
STORAGE TIME: The time between the end
of the input pulse and the time when the
output pulse has decreased to 90 per cent
of its maximum amplitude.
FALL TIME: The time interval during which
the amplitude of the output voltage changes