Datasheet

APPLICATION INFORMATION
WIDEBAND, NONINVERTING OPERATION
_
+
THS3091
R
F
1.21 kΩ
49.9 Ω
0.1 µF 6.8 µF
−V
S
−15 V
R
G
50-Ω Source
+
V
I
0.1 µF 6.8 µF
+
+V
S
15 V
1.21 kΩ
49.9 Ω
50-Ω LOAD
THS3091
THS3095
www.ti.com ........................................................................................................................................ SLOS423G – SEPTEMBER 2003 – REVISED OCTOBER 2008
Current-feedback amplifiers are highly dependent on
the feedback resistor R
F
for maximum performance
The THS3091/5 are unity gain stable 235-MHz
and stability. Table 1 shows the optimal gain-setting
current- feedback operational amplifiers, designed to
resistors R
F
and R
G
at different gains to give
operate from a ± 5-V to ± 15-V power supply.
maximum bandwidth with minimal peaking in the
Figure 59 shows the THS3091 in a noninverting gain
frequency response. Higher bandwidths can be
of 2-V/V configuration typically used to generate the
achieved, at the expense of added peaking in the
performance curves. Most of the curves were
frequency response, by using even lower values for
characterized using signal sources with 50- Ω source
R
F
. Conversely, increasing R
F
decreases the
impedance, and with measurement equipment
bandwidth, but stability is improved.
presenting a 50- Ω load impedance.
Table 1. Recommended Resistor Values for
Optimum Frequency Response
THS3091 and THS3095 R
F
and R
G
values for minimal peaking
with R
L
= 100 Ω
SUPPLY VOLTAGE
GAIN (V/V) R
G
( Ω ) R
F
( Ω )
(V)
± 15 – 1.78 k
1
± 5 – 1.78 k
± 15 1.21 k 1.21 k
2
± 5 1.15 k 1.15 k
± 15 249 1 k
5
± 5 249 1 k
± 15 95.3 866
10
± 5 95.3 866
– 1 ± 15 and ± 5 1.05 k 1.05 k
Figure 59. Wideband, Noninverting Gain
– 2 ± 15 and ± 5 499 1 k
Configuration
– 5 ± 15 and ± 5 182 909
– 10 ± 15 and ± 5 86.6 866
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