THS3491 Datasheet, PDF (12/28 Pages) Texas Instruments – 900-MHz, High-Power Output, Current Feedback Amplifier

THS3491
SBOS875 – AUGUST 2017
www.ti.com
8.4 Device Functional Modes
8.4.1 Wideband, Noninverting Operation
The THS3491 is a 900-MHz current-feedback operational amplifiers, designed to operate from a ±7-V to ±16-V
power supply.
Figure 7 shows the THS3491 in a noninverting, gain of 5 V/V configuration typically used to generate the
performance curves. Most of the curves were characterized using signal sources with 50-Ω source impedance,
and with measurement equipment presenting a 50-Ω load impedance.
15 V
RG
143
RF
576
0.1 …F
+
6.8 …F
50-Ÿ 6RXUFH
VI
RT
49.9
±
+
THS3491
0.1 …F
49.9
50-Ÿ /RDG
+
6.8 …F
±15 V
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Figure 7. Wideband, Noninverting Gain of 5 V/V Configuration
Current-feedback amplifiers are highly dependent on the feedback resistor, R_F, for maximum performance and
stability. Table 2 shows the optimal resistor values for R_F and R_G at different gains in order to achieve maximum
bandwidth with minimal peaking in the frequency response. Higher bandwidths can be achieved by using even
lower values for R_F, at the expense of added peaking in the frequency response. Conversely, increasing R_F
decreases the bandwidth, but stability is improved.
Table 2. Recommended Resistor Values for Minimum Peaking and Optimal Frequency Response
With R_L = 100 Ω and V_S = ±15-V
GAIN (V/V)
2
R_G (Ω)
976
RGT PACKAGE
R_F (Ω)
976
DDA PACKAGE
R_G (Ω)
2.1k
R_F (Ω)
2.1k
5
143
576
200
798
10
54.9
499
78.7
704
20
20
383
29.4
564
12
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