THS3091 Datasheet, PDF (27/45 Pages) Texas Instruments – HIGH-VOLTAGE, LOW-DISTORTION, CURRENT-FEEDBACK OPERATIONAL AMPLIFIERS

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Device Functional Modes (continued)
THS3091, THS3095
SLOS423H – SEPTEMBER 2003 – REVISED DECEMBER 2015
15 V _+VS
+
50-Ω Source
0.1 µF
6.8 µF
V_I
49.9 Ω
+
THS3091
_
R_F
49.9 Ω
50-Ω LOAD
1.21 kΩ R_G
1.21 kΩ
0.1 µF
6.8 µF
+
−V_S
−15 V
Figure 60. Wideband, Noninverting Gain Configuration
Current-feedback amplifiers are highly dependent on the feedback resistor R_F for maximum performance and
stability. Table 4 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.
Table 4. Recommended Resistor Values for Optimum Frequency Response
GAIN (V/V)
1
2
5
10
–1
–2
–5
–10
THS3091 and THS3095 R_F and R_G values for minimal peaking with R_L = 100 Ω
SUPPLY VOLTAGE (V)
R_G (Ω)
±15
–
±5
–
±15
1.21 k
±5
1.15 k
±15
249
±5
249
±15
95.3
±5
95.3
±15 and ±5
1.05 k
±15 and ±5
499
±15 and ±5
182
±15 and ±5
86.6
R_F (Ω)
1.78 k
1.78 k
1.21 k
1.15 k
1k
1k
866
866
1.05 k
1k
909
866
7.3.2 Wideband, Inverting Operation
Figure 61 shows the THS3091 in a typical inverting gain configuration where the input and output impedances
and signal gain from Figure 60 are retained in an inverting circuit configuration.
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