LTC6601-1
22
66011f
APPLICATIONS INFORMATION
A GALLERY OF BASIC FILTER TOPOLOGIES
Tables 2 through 10 list (sorted by Gain) a hundred possible
fi lter topologies that can be easily implemented with the
LTC6601. The tables also list the LTC6601-1 approximate
midband (1MHz) spot noise e
in
referred to the input re-
sistor, R1 (with the BIAS pin pulled to V
+
). The gains for
these topologies range from 1V/V to 7V/V. The Qs listed
are within the range of 0.54 and 1.72. The f
O
s listed are
in the range of 6.96MHz and 22.71MHz, and the –3dB
frequencies listed range from 5.5MHz to 27.5MHz. For
all fi lters listed, R3 = 125Ω. Figures 7 to 10 show how to
pin-strap each fi lter confi guration.
Table 2. Gain of 7 Filter Confi gurations
GAIN
f
O
(MHz) f
–3dB
(MHz) Q R1 () R2 () C1 (pF) C2 (pF)
e
in
(nV/√Hz)V/V dB
7.0 16.902 10.38 7.43 0.539 57.14 400.00 48.2 97.6 3.7
7.0 16.902 9.57 10.36 0.771 57.14 400.00 48.2 114.8 3.7
7.0 16.902 8.96 12.10 1.175 57.14 400.00 48.2 130.9 3.7
7.0 16.902 8.12 7.49 0.656 57.14 400.00 58.75 130.9 3.7
Table 3. Gain of 6 Filter Confi gurations
GAIN
f
O
(MHz) f
–3dB
(MHz) Q R1
()R2
()C1
(pF) C
2
(pF)
e
in
(nV/√Hz)V/V dB
6.0 15.563 10.38 10.03 0.684 66.67 400.00 48.2 97.6 3.8
6.0 15.563 9.57 12.52 1.071 66.67 400.00 48.2 114.8 3.8
6.0 15.563 8.67 7.67 0.634 66.67 400.00 58.75 114.8 3.8
6.0 15.563 8.12 9.59 0.870 66.67 400.00 58.75 130.9 3.8
6.0 15.563 7.47 6.07 0.592 66.67 400.00 69.3 130.9 3.8
Table 4. Gain of 5 Filter Confi gurations
GAIN
f
o
(MHz) f
–3dB
(MHz) Q R1 ()R2
() C1 (pF) C2 (pF)
e
in
nV/√HzV/V dB
5.0 13.979 11.36 9.67 0.614 80.00 400.00 48.2 81.5 4.0
5.0 13.979 10.38 12.78 0.936 80.00 400.00 48.2 97.6 4.0
5.0 13.979 9.40 7.67 0.594 80.00 400.00 58.75 97.6 4.0
5.0 13.979 8.67 10.07 0.849 80.00 400.00 58.75 114.8 4.0
5.0 13.979 8.12 11.25 1.290 80.00 400.00 58.75 130.9 4.0
5.0 13.979 7.98 6.46 0.591 80.00 400.00 69.3 114.8 4.0
5.0 13.979 7.47 8.16 0.779 80.00 400.00 69.3 130.9 4.0
5.0 13.979 6.96 5.50 0.579 80.00 400.00 79.85 130.9 4.0