Tektronix AFG3000 Series Manual page 16

Tektronix AFG3000 Series Function Generator Guide v1.0
Example:
You connect a function generator with output impedance R
resistance of R . You configure the generator to output a sinusoid of amplitude V
L
f . The voltage V across the load is monitored with an oscilloscope using a 1× probe. The oscilloscope
SET L
has an input resistance of R
Function
Generator
Probe
Test
Circuit
Ground
The function generator "sees" the load in parallel with the oscilloscope's input impedance:
= =
Z R || R || Z
EQ L in C
in
Table 3: Calculated load voltage V
(Ω)
R
L
= 0 Hz (DC)
f
SET
10 0.3333
50 1.0000
100 1.3333
500 1.8181
1000 1.9047
10K 1.9900
100K 1.9998
= 1M Ω in parallel with an input capacitance of C
in
Scope
Figure 11: Example test circuit with oscilloscope
−
1
 
1 1
ω
+ +
   
j C
in
R R
 
L in
versus load resistance R
L
Given V = 1 V
SET p-p
= 1 MHz
f
SET
0.3333
1.0000
1.3333
1.8181
1.9047
1.9899
1.9998
= 50 Ω to a test circuit which has a load
O
Function Test
Generator Circuit
R
O
V
G
R R
=
in L
ω
+ +
R R j C R
L in in in
at specific signal frequencies f
L
= 1M Ω, C
, R = 15 pF
in in
V (volts)
L
= 50 MHz = 100 MHz
f f
SET SET
0.3331 0.3323
0.9931 0.9733
1.3171 1.2720
1.7778 1.6712
1.8585 1.7377
1.9374 1.8017
1.9465 1.8090
15
Portland State University
= 1 V at frequency
SET p-p
= 15 pF.
in
Oscilloscope
R V R
L L in

2 Z

→ =
V

+
L
R Z

L EQ
= 200 MHz
f
SET
0.3293
0.9046
1.1290
1.3807
1.4175
1.4516
1.4554
C
in


EQ
V

SET
R

O
SET