TS615 ST Microelectronics, Inc., TS615 Datasheet - Page 15

• Manufacturer Part Number: TS615
• Description: Dual Wide Band Operational Amplifier
• Manufacturer: ST Microelectronics, Inc.

INTERMODULATION DISTORTION PRODUCT
A non-ideal output of the amplifier can be de-
scribed by the following development :
due to a non-linearity in the input-output amplitude
transfer. In the case of the input is V
is the DC component, C
C
signal V
A one-frequency (one-tone) input signal contrib-
utes to a harmonic distortion. A two-tones input
signal contributes to a harmonic distortion and in-
termodulation product.
This intermodulation product or intermodulation
distortion study of a two-tones input signal is the
first step of the amplifier characterization of driving
capability in the case of a multi-tone signal.
In this case :
and :
n
A
is the amplitude of the harmonics of the output
3
+
+
sin
Vout
3C
----------------------- -
3C
----------------------- -
+ C
V o ut
out
2
3
1
3
2
A
2
–
t
A
.
=
2
+
2
C
------- A
+
2
2
AB
B
V
2
C 0
V
=
B
B
+
+
+
C
out
in
3
C
sin
C
C
3
C
sin
sin
+
cos
2
2
A
n
0
1
=
C 1 V in
cos
3
=
A
+
–
A
A
A
2
sin
sin
C
2
+
C
sin
sin
sin
+
2
1
t
1
1
0
1
3
+
C
+
3
–
+
–
A
1
C
------- ¥
n
2A
+
1
1
2
1
1
4
1
1
t
C
(V
sin
t
3
C 2 V
t
t
+
t
V
2
t
2
+
2
2
+
2
+
+
+
in
in
B
B
B
t
t
B
A
-------------------- -
B
B
B
) is the fundamental,
t
2
–
–
1
sin
sin
–
2
n
2
3
sin
1
-- -
2
sin
sin
cos
t
cos
1
-- -
2
in
sin
+
sin
+
2
sin
+
B
B
1
2
2
3
2
2
2
2
sin
t
t
2
t
t
t
+
in
2
1
2
2
C n V
n
1
2AB
t
=Asin t, C
1
–
t
+
2
+
t
2
2
n
2
in
2
t
sin
2
t
t
2
t
0
In this expression, we recognize the second order
intermodulation IM2 by the frequencies (
and (
IM3 by the frequencies (2
(
The measurement of the intermodulation product
of the driver is achieved by using the driver as a
mixer by a summing amplifier configuration. By
this way, the non-linearity problem of an external
mixing device is avoided.
Figure 45 : Non-inverting Summing Amplifier
The following graphs show the IM2 and the IM3 of
the amplifier in different configuration. The
two-tones input signal is achieved by the multi-
source generator Marconi 2026. Each tone has
the same amplitude. The measurement is
achieved by the spectrum analyzer HP3585A.
Vin1
Vin1
50
50
1
No rth Hills
No rth Hills
1: 2
1: 2
0 315PB
0 315PB
+2
1
400
400
Vin2
Vin2
50
50
2
) and (
2
49.9
49.9
49.9
49.9
1: 2
1: 2
No rth Hills
No rth Hills
) and the third order intermodulation
0 315PB
0 315PB
400
400
49.9
49.9
49.9
49.9
1k
1k
1
1k
1k
1k
1k
1k
1k
Rg1
Rg1
Rg2
Rg2
10
10
11
11
2
+
+
_
_
_
_
+
+
1/2
1/2
1/2
1/2
).
Rfb1
Rfb1
Rfb2
Rfb2
TS615
TS615
TS615
TS615
-Vcc
-Vcc
+Vcc
+Vcc
Vout diff.
Vout diff.
13
13
1
-
33
33
33
33
49.9
49.9
49.9
49.9
2
), (2
100
100
TS615
North Hills
North Hills
0315PB
0315PB
2:1
2:1
1
1
15/27
-
50
50
2
2
),
)