THS3202 Datasheet, PDF (26/32 Pages) Texas Instruments – 2-GHZ, LOW DISTORTION, CURRENT FEEDBACK AMPLIFIERS

THS3202
SLOS242D − SEPTEMBER 2002 − REVISED JANUARY 2004
www.ti.com
There are two simple ways to create an integrator with a CFB amplifier. The first, shown in Figure 98, adds a resistor
in series with the capacitor. This is acceptable because at high frequencies, the resistor is dominant and the feedback
impedance never drops below the resistor value. The second, shown in Figure 99, uses positive feedback to create
the integration. Caution is advised because oscillations can occur due to the positive feedback.
Rg
VI
Rf
C1
−
+
VO
THS3202
ȡ ȣ _VO
ǒ Ǔ_{ȧȢ ȧȤ VI}
+
Rf
Rg
S
)
1
RfC1
S
Figure 98. Inverting CFB Integrator
Rg
Rf
−
THS320x
+
R1
VI
RA
R2
C1
For Stable Operation:
R2
R1 || RA ^≥
Rf
Rg
VO
( ) ^{VO ≅ VI}
1+
Rf
Rg
sR1C1
Figure 99. Noninverting CFB Integrator
The THS3202 may also be employed as a very good video distribution amplifier. One characteristic of distribution
amplifiers is the fact that the differential phase (DP) and the differential gain (DG) are compromised as the number
of lines increases and the closed-loop gain increases. Be sure to use termination resistors throughout the distribution
system to minimize reflections and capacitive loading.
Rg
Rf
75-Ω Transmission Line
−
75 Ω
VI
+
VO1
THS3202
75 Ω
N Lines
75 Ω
75 Ω
75 Ω
VON
Figure 100. Video Distribution Amplifier Application
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