Datasheet

´
¶
C
=
2S LC
1
R
F
-
R
G
C
2
R
2
R
1
C
1
V
O
V
IN
21211
)RR(C)K1(CR ++-
=
1
pp
QZ
2121
CCRR
=
1
2
p
Z
K
#
pp
Q
s
1 +
Z
+
2
s
2
p
Z
o
V
IN
V
R
B
R
F
C
R
R
S
V
O
V
IN
-
+
50:
50:
R
G
R
F
= R
B
R
G
= R
S
||R
V
O
#V
IN
K
O
sR
S
C
;
K
O
= 1 +
R
F
R
G
LMH6629
SNOSB18G –APRIL 2010–REVISED MARCH 2013 www.ti.com
LOW-NOISE INTEGRATOR
Figure 67 shows a deBoo integrator implemented with the LMH6629. Positive feedback maintains integration
linearity. The LMH6629’s low input offset voltage and matched inputs allow bias current cancellation and provide
for very precise integration. Keeping R
G
and R
S
low helps maintain dynamic stability.
Figure 67. Low-Noise Integrator
HIGH-GAIN SALLEN-KEY ACTIVE FILTERS
The LMH6629 is well suited for high-gain Sallen-Key type of active filters. Figure 68 shows the 2
nd
order Sallen-
Key low-pass filter topology. Using component predistortion methods discussed in OA-21 enables the proper
selection of components for these high-frequency filters.
Figure 68. Low Pass Sallen-Key Active Filter Topology
LOW-NOISE MAGNETIC MEDIA EQUALIZER
Figure 69 shows a high-performance low-noise equalizer for such applications as magnetic tape channels using
the LMH6629. The circuit combines an integrator (used to limit noise) with a bandpass filter (used to boost the
response centered at a frequency or over a band of interest) to produce the low-noise equalization. The circuit’s
simulated frequency response is illustrated in Figure 70.
In this circuit, the bandpass filter center frequency is set by
(11)
26 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated
Product Folder Links: LMH6629