Tektronix FG 5010 User Manual

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Refer to Fig . 4-1 , which is an illustration of a basic func
tion generator . Bipolar current is fed to a switch , which con
trols the direction of flow to a capacitor . The change in
charge of the capacitor produces a ramp voltage that is fed
through a buffer , then to a comparator . This comparator
senses the crossing of the ramp voltage against a reference ,
and
controls the
current switch . The
resulting outputs are a
triangle function from the buffer , and a square wave function
from
the
comparator .
BLOCK DIAGRAM DESCRIPTION
The output of the function generator is fed to a shaping
circuit , which shapes the triangle into a sinusoidal function .
From there , the sine , square , and triangle functions are fed
through a function selector , which applies one of the signals
to an
output
amplifier
.
Refer to Fig . 4-2 , which is an elaboration of Fig . 4-1 . In
this illustration , the original loop remains , but the currents
@
SWITCH
THE
BUFFER
COMPARATOR
Ful
are now controllable . This permits frequency modulation of
the loop triangle signal , VCF ( voltage - controlled frequency )
control , and CPU control of such factors as the starting
point
for the
signal , switch
- point
compensation to allow
for
high
-
frequency or odd -
symmetry
situations .
Out of the com
parator ,
the
square -
wave signal is
applied
to the
function
selector as before , but it is also applied to a counter that
feeds
a
digital - to -
analog converter
. This
circuit divides
the
signal by a factor of 100,000 , incrementing and dec
rementing the DAC
input with
1000 up counts
and 1000
down counts to produce an output triangle - wave signal that
is a precise sub - multiple of the input square - wave signal .
This output signal is applied to the function selector and to
the shaper for shaping into a sine - wave signal . The counter
also produces a low - frequency square wave that is a
100,000 submultiple of the applied square - wave signal . This
is also applied to the function selector . The selected signal is
applied to
the output
amplifier ,
where amplitude
modulation
is added if appropriate , and offset is also added to the
signal .
SHAPER
n
FUNCTION
SELECTOR
Theory of
Operation
- FG
5010
Fig
. 4-1 . Basic Function
Generator .
OUTPUT
AMPLIFIER
3467-08
4-3

Tektronix FG 5010 Specifications

General

Brand	Tektronix
Model	FG 5010
Category	Portable Generator
Language	English