Datasheet
APPLICATION INFORMATION
Wideband Noninverting Operation
Wideband Inverting Gain Operation
_
+
THS3201
R
F
768 Ω
49.9 Ω
100 pF
0.1 µF 6.8 µF
-V
S
-7.5 V
R
G
50 Ω Source
+
V
I
100 pF
0.1 µF 6.8 µF
+
+V
S
7.5 V
50 Ω
768 Ω
49.9 Ω
_
+
THS3201
R
G
287 Ω
100 pF
0.1 µF 6.8 µF
-V
S
-7.5 V
50 Ω Source
+
V
I
100 pF
0.1 µF 6.8 µF
+
+V
S
7.5 V
R
F
576 Ω
R
M
60.4 Ω
50 Ω
49.9 Ω
THS3201-EP
SGLS283B – APRIL 2005 – REVISED JANUARY 2009 .....................................................................................................................................................
www.ti.com
Table 1. Recommended Resistor Values for
Optimum Frequency Response
The THS3201 is a unity gain stable 1.8-GHz
THS3201 R
F
for AC When R
load
= 100 Ω
current-feedback operational amplifier, designed to
Gain Supply Voltage R
G
R
F
operate from a ± 3.3-V to ± 7.5-V power supply.
(V/V) (V) ( Ω ) ( Ω )
Figure 56 shows the THS3201 in a noninverting gain
± 7.5 — 1.2 k
1
of 2-V/V configuration typically used to generate the
± 5 — 1.2 k
performance curves. Most of the curves are
± 7.5 768 768
characterized using signal sources with 50- Ω source
2
± 5 715 715
impedance, and with measurement equipment
presenting a 50- Ω load impedance. The 49.9- Ω shunt
± 7.5 154.9 619
5
resistor at the V
I
terminal in Figure 56 matches the
± 5 143 576
source impedance of the test generator.
± 7.5 54.9 487
10
± 5 51.1 464
± 7.5 619 619
– 1
± 5 576 576
– 2 ± 7.5 and ± 5 287 576
– 5 ± 7.5 and ± 5 110 549
– 10 ± 7.5 and ± 5 49.9 499
Figure 57 shows the THS3201 is a typical inverting
gain configuration, where the input and output
impedances and signal gain from Figure 56 are
retained in an inverting circuit configuration.
Figure 56. Wideband Noninverting Gain
Configuration
Unlike voltage-feedback amplifiers, current-feedback
amplifiers are highly dependent on the feedback
resistor R
F
for maximum performance and stability.
Table 1 shows the optimal gain setting resistors R
F
and R
G
at different gains to give maximum bandwidth
with minimal peaking in the frequency response.
Higher bandwidths can be achieved, at the expense
of added peaking in the frequency response, by using
even lower values for R
F
. Conversely, increasing R
F
decreases the bandwidth, but stability is improved.
Figure 57. Wideband Inverting Gain Configuration
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