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VOUT
+
-
VIN
+VSUPPLY
CPOS
0.1 PF
6.8 PF
4.7 k:
22 PF
10
1000
FREQUENCY (MHz)
-10
-6
-2
2
N
O
R
MAL
IZ
ED
G
AI
N
(d
B
)
100
0
-4
-8
1
-1
-3
-5
-7
-9
UNCOMPENSATED
CP = 1.2 pF
CP = 2.2 pF
V
+
= 5V
AV = +1 V/V
VOUT = 0.2 VPP
+
-
RIN
50:
RS
100:
ROUT
50:
CP
2.2 pF
VIN
VOUT
OBSOLETE
SNOSAY0C – JUNE 2007 – REVISED APRIL 2013
UNITY GAIN COMPENSATION
With a current feedback Selectable Gain Buffer like the LMH6734, the feedback resistor is a compromise
between the value needed for stability at unity gain and the optimized value used at a gain of two. The result of
this compromise is substantial peaking at unity gain. If this peaking is undesirable a simple RC filter at the input
of the buffer will smooth the frequency response as shown in
Figure 41. Figure 42 shows the results of a simple
filter placed on the non-inverting input. See
Figure 43 and
Figure 44 for another method of reducing unity gain
peaking.
Figure 41. Correction for Unity Gain Peaking
Figure 42. Frequency Response for Circuit in Figure 41 Figure 43. Alternate Unity Gain Compensation
Copyright 2007–2013, Texas Instruments Incorporated
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