TS616IDWT(2002) View Datasheet(PDF) - STMicroelectronics
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Description
Manufacturer
TS616IDWT Datasheet PDF : 27 Pages
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TS616
INTERMODULATION DISTORTION PRODUCT
Non-ideal output of the amplifier can be described
by the following series:
Vout = C0 + C1Vin + C2V2in + …CnVnin
due to non-linearity in the input-output amplitude
transfer, where the input is Vin=Asinωt, C0 is the
DC component, C1(Vin) is the fundamental and Cn
is the amplitude of the harmonics of the output sig-
nal Vout.
A one-frequency (one-tone) input signal contrib-
utes to harmonic distortion. A two-tone input sig-
nal contributes to harmonic distortion and inter-
modulation product.
The study of the intermodulation/distortionfor a
two-tone input signal is the first step in character-
izing the driving capability of multi-tone input sig-
nals.
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----A----2----B--
2
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. In this
way, the non-linearity problem of an external mix-
ing device is avoided.
Figure 45: Non-inverting Summing Amplifier for
Intermodulation measurements
1kΩ
Vin1
1:√2
50Ω
100Ω
49.9Ω
1kΩ
49.9Ω
Vin1
50Ω
1:√2
100Ω
+
+Vcc
1/2TS616
_
910Ω
300Ω
300Ω
910Ω
Vout diff.
49.9Ω
Rout1
Rout2
49.9Ω
1kΩ
1kΩ
_
1/ 2TS616
+
-Vcc
49.9Ω
100Ω
√2:1
50Ω
49.9Ω
The following graphs show the IM2 and the IM3 of
the amplifier in different configurations. The
two-tone input signal was generated by the multi-
source generator Marconi 2026. Each tone has
the same amplitude. The measurement was per-
formed using a HP3585A spectrum analyzer.
15/27
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