TS615IPWT View Datasheet(PDF) - STMicroelectronics
Part Name
Description
Manufacturer
TS615IPWT Datasheet PDF : 27 Pages
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TS615
INTERMODULATION DISTORTION PRODUCT
A non-ideal output of the amplifier can be de-
scribed by the following development :
Vout
=
C
0
+
C1
Vin
+
2
C2V i
n
+
…
Cn
n
V in
due to a non-linearity in the input-output amplitude
transfer. In the case of the input is Vin=Asinωt, C0
is the DC component, C1(Vin) is the fundamental,
Cn is the amplitude of the harmonics of the output
signal Vout.
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 :
+ C2(A sin ω1t + B sin ω2t)2
… + Cn(A sin ω1t + B sin ω2t)n
Vin = A sinω1t + B sinω2t
and :
Vo ut = C0 + C1(A sin ω1t + B sin ω2t)
+ C1(A sinω1 t + B sinω2 t)
–C---2--2--A2 cos 2ω1t + B2 cos 2ω2t
+ 2 C2AB( cos (ω1 – ω2)t – cos(ω1 – ω2)t)
+
3
-C--4--3--
¥
+ C3A3 sin3ω1 t + B3 sin 3ω2t
+
3----C-----3--2--A----2----B--
sin
(
2ω1
–
ω2
)t
–
12--
sin
(2
ω1
+
ω
2 ) t
+
3----C-----3--2--A----2----B--
sin
(
–ω1
+
2
ω)
2
t
–12--
sin
(ω1
+
2
ω
2
)
t
… + Cn(Vin)n
Vout
=
C
0
+
C2
A-----2-----+2-----B----2--
A3 sinω1t + B3 sin ω2t + 2A2B sin ω1t + 2AB2 sinω2t
In this expression, we recognize the second order
intermodulation IM2 by the frequencies (ω1-ω2)
and (ω1+ω2) and the third order intermodulation
IM3 by the frequencies (2ω1-ω2), (2ω1+ω2),
(−ω1+2ω2) and (ω1+2ω2).
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
1kΩ
Vin1
1:√2
50Ω
400Ω
49.9Ω
1kΩ
49.9Ω
No rth Hills
0 315PB
Vin2
1:√2
50Ω
400Ω
No rth Hills
0 315PB
49.9Ω
1kΩ
1kΩ
11
+
+Vcc
1/2TS615
10 _
13
Rfb1
Rg1
Vout diff.
Rg2
Rfb2
_
1/2TS615
+
-Vcc
49.9Ω
49.9Ω
33Ω
33Ω
√2:1
100Ω
50Ω
North Hills
0315P B
49.9Ω
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.
15/27
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