THS3062DGNR Datasheet, PDF (18/33 Pages) Texas Instruments – LOW-DISTORTION, HIGH SLEW RATE, CURRENT-FEEDBACK AMPLIFIERS

THS3061
THS3062
SLOS394B – JULY 2002 – REVISED NOVEMBER 2009
R_f
R_g
Input
_
THS306x
+
10 Ω
Output
C_LOAD
Figure 53. Driving a Capacitive Load
General Configurations
A common error for the first-time CFB-amplifier user
is creating a unity gain buffer amplifier by shorting the
output directly to the inverting input. In this
configuration, a CFB amplifier oscillates, and is not
recommended. The THS306x, like all CFB amplifiers,
must have a feedback resistor for stable operation.
Additionally, placing capacitors directly from the
output to the inverting input is not recommended,
because at high frequencies, a capacitor has a very
low impedance. This results in an unstable amplifier
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and should not be considered when using a
current-feedback amplifier. Because of this,
integrators and simple low-pass filters, which are
easily implemented on a VFB amplifier, must be
designed slightly differently. If filtering is required,
simply place an RC-filter at the noninverting terminal
of the operational-amplifier (see Figure 54).
R_g
R_f
V_I
R1
–
+
C1
f–3dB
+
1
2pR1C1
V_O
ǒ Ǔǒ Ǔ ^VO
VI
+
1
)
Rf
Rg
1
1 ) sR1C1
Figure 54. Single-Pole Low-Pass Filter
18
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