THS3061 Datasheet, PDF (21/25 Pages) Texas Instruments – LOW DISTORTION HIGH SLEW RATE CURRENT FREEBACK AMPLIFIERS

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THS3061
THS3062
SLOS394A – JULY 2002 – OCTOBER 2002
There are two simple ways to create an integrator with a CFB amplifier. The first, shown in Figure 56, 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 57, uses positive feedback to create
the integration. Caution is advised because oscillations can occur due to the positive feedback.
Rg
VI
Rf
C1
–
+
VO
THS306x
ȡ ȣ _VO
ǒ Ǔ_{ȧȢ ȧ VI}
+
Rf
Rg
S
)
1
RfC1
S
Figure 56. Inverting CFB Integrator
Rg
Rf
–
THS306x
+
VO
R1
VI
RA
R2
C1
For Stable Operation:
R2
R1 || RA ^≥
Rf
Rg
( ) ^{VO ≅ VI}
1+
Rf
Rg
sR1C1
Figure 57. Noninverting CFB Integrator
The THS306x 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
THS306x
75 Ω
N Lines
75 Ω
75 Ω
75 Ω
VON
Figure 58. Video Distribution Amplifier Application
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