LMH6738 Datasheet, PDF (9/20 Pages) National Semiconductor (TI) – Very Wideband, Low Distortion Triple Op Amp

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LMH6738
SNOSAC1E – APRIL 2004 – REVISED MARCH 2013
APPLICATION INFORMATION
+5V _{6.8 µF}
V_IN
R_IN
C_SS
0.1 µF
0.01 µF ^AV ^{= 1 +R}F^/RG ^{= V}OUT^/VIN
C_POS
+
V_OUT
-
C_NEG
0.01 µF ^RF
R_G
6.8 µF
-5V
Figure 22. Recommended Non-Inverting Gain
Circuit
+5V _{6.8 µF}
C_SS
25: _{0.1 µF}
V_IN
R_G
0.01 µF
C_POS
+
R_F V_OUT
A_V = _RG = _VIN
V_OUT
-
C_NEG
R_F
0.01 µF
R_T
6.8 µF
SELECT R_T TO
YIELD DESIRED
-5V
R_IN = R_T||R_G
Figure 23. Recommended Inverting Gain Circuit
GENERAL INFORMATION
The LMH6738 is a high speed current feedback amplifier, optimized for very high speed and low distortion. The
LMH6738 has no internal ground reference so single or split supply configurations are both equally useful.
EVALUATION BOARDS
Texas Instruments provides the following evaluation boards as a guide for high frequency layout and as an aid in
device testing and characterization. Many of the data sheet plots were measured with these boards.
Device
LMH6738MQA
Package
SSOP
Evaluation Board
Part Number
LMH730275
FEEDBACK RESISTOR SELECTION
One of the key benefits of a current feedback operational amplifier is the ability to maintain optimum frequency
response independent of gain by using appropriate values for the feedback resistor (R_F). The Electrical
Characteristics and Typical Performance plots specify an R_F of 550Ω, a gain of +2 V/V and ±5V power supplies
(unless otherwise specified). Generally, lowering R_F from it’s recommended value will peak the frequency
response and extend the bandwidth while increasing the value of R_F will cause the frequency response to roll off
faster. Reducing the value of R_F too far below it’s recommended value will cause overshoot, ringing and,
eventually, oscillation.
Copyright © 2004–2013, Texas Instruments Incorporated
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